02 - Learn Unit Conversions, Metric System & Scientific Notation in Chemistry & Physics

hi I'm Jason and welcome to this section of the chemistry tutor and this section we're going to talk about units and unit conversions and so don't forget chemistry is a mathematical science so yes we're going to be talking about reactions and molecules and things like that but mostly we're going to be interested in calculating how much of something happens how fast does a reaction proceed is it a violent reaction or does it take years to happen so we're going to be dealing with numbers and so as a preface to that we need to be comfortable with the SI system of units which is the the standard system that we use when we talk about chemistry and also physics and other branches of math and science and so in order to do that we're going to talk about units and then I'm going to teach you one little thing here at the end which is probably the most important thing you can learn as you start chemistry or any any study of any science it's the most important thing I know that it saved my life in terms of doing a problem many many times and that's how to convert units properly it's so incredibly important I cannot stress how important it is now let me go ahead and say right now that this section right here is going to be a pretty good primer for you to just watch it understand what you need to understand and plow right on into to doing your chemistry problems but I will say that for those of you who don't know I have already created a I think it's four hours of unit conversions a unit conversion to tour DVD that you can go look at on the website and get and that has everything that I'm talking about here exploded up into even more detail with a lot more problems to give you practice so if there is it any confusion and all on scientific notation SI system of units unit conversions go get yourself a copy of the unit conversion tutor because it extensively teaches you that stuff and I cannot stress how important it is because when you learn how to convert units properly you can almost do all of your problems without really thinking about what to do if you know how to do units properly so let's start here at the beginning for those of you again who don't know we have the SIS system of units right so for length here in the US we a lot of times talk about miles and inches and feet and things like that but when you get into science just throw out the idea of miles and inches and feet in cubic feet and things like that just throw them out because we never use them in engineering science or anything like that we're always on the SI system which is called the metric system right so the unit of length that we're gonna be talking about in chemistry the basic I should say the base unit of length is called a meter and I know you've heard of that before and we abbreviate that with the letter M a meter is pretty close to a yard for those of you who need something to help you visualize that it's if you stretch your arms out like this that's about a meter it's just to give you a kind of a ballpark estimate of how big that is and this is the base unit here all right now the unit of mass which is how much of something we have you know in your hand you know and how much of how much of a quantity of anything you have the base unit that we're going to always use is the kilogram which is K G which we'll talk about how that's related to the gram here a second but basically gram kilogram they're all in the same family they're talking about mass all right time finally something that doesn't change we use the second so letter s and for temperature the SI base unit of temperature is actually something called the Kelvin which is symbolized by the letter K now later on in chemistry we will use the Kelvin pretty extensively I mean the Kelvin just just so you know it's kind of interesting zero degrees Kelvin is when all atomic motion stops you know when you say something has temperature it means the atoms are vibrating that's what it means when you heat something up the atoms vibrating even more when you cool something down the atoms are vibrating less so the Kelvin temperature scale is the absolute temperature scale when you say zero Kelvin you mean everything stops no atom is moving at all it's not even jittering even a tiny zero degrees Kelvin is impossible to reach it's impossible to get there even deep deep space is not zero degrees Kelvin but that's the absolute temperature scale now we will use it some you know some point later in chemistry but most of the time we're actually gonna use Celsius which is the letter C and Celsius is something you're probably more familiar with Celsius is the scale we're a hundred degrees Celsius is a boiling point of water zero degrees Celsius is the freezing point of water will never use Fahrenheit I shouldn't say never but it's rare that we would ever use a Fahrenheit temperature scale in chemistry or in physics or any other math and science so these are the base units we're gonna use meter for length kilogram for mass seconds for time and mostly we're gonna use Celsius for temperature but the actual SI system of units calls for Kelvin to be the base so just so you know that there now let's talk a little bit about metric prefixes let me change colors here a little bit let me talk about metric prefixes now let me give you a little secret everyone has heard of a meter I think everyone's heard of a millimeter everyone's heard of a centimeter everyone's heard of a kilometer right see the base word has meter in it but all of these things in the front are just prefixes that sort of change that change what you're really talking about a little bit that's why the metric system is so powerful and so useful because all of the base units are the same distance length time and everything else but we have all these prefixes that sort of change what we're talking about here so when we talk about kilometres we're talking about a large unit a kilo of something is a large unit right we talked about milli or micro or nano you might think of you know teeny tiny little nano meter that's a teeny tiny little thing that's that's very very very small so we're gonna talk a little bit about these metric prefixes because these they're really the secret to understanding the metric system is all in the prefixes so we have the kilo which is a metric prefix and what kilo means is 10 to the power of 3 and for those of you a little bit rusty on your algebra 10 to the power of three means 1,000 so it's a thousand of something so if the base unit of length let's talk about meters it's about this far that's a meter right then a kilo meter is 1000 meters and that's the unit of what we call a kilometer so a kilometres really far it's a thousand of these meters right and that's that's another unit we call a kilometer so in the English system in the US system I should say we have miles and we have inches and we have feet and we have all these other things we know that these different units are different lengths we know that an inch is about that big we know that a foot is about that big and we know a mile is you know down the road to the store it's pretty big right but they're all different words and they're not connected and they're not multiples of each other very nicely this is a nice 1,000 is a nice nice power of 10 multiple so it's it's really really nice to have that we'll talk about how later when we talk about unit conversions but in the metric system everything is going to be a power of 10 related to each other so it makes it really easy to work with so take the time to understand it because when you do it will make your life easier so to give you an example here in terms of kilo we say that one kilometer is equal to 1,000 meters so when you read the word kilometer this kilo here just replace it in your mind with 1000 so instead of reading it is one kilometer read it as 1,000 meters that's what you should say because kilo means 1000 it's like a it's like you substitute in or something and so you put this here in your mind you're reading 1,000 meters here one unit of 1,000 meters that's what that is one kilogram is equal to 1,000 grams a gram is a pretty small unit of measure right but we're talking about a kilogram it's 1,000 gram so again in them in your mind you can take kilo and replace it with 1,000 so you could sort of in your mind you could say one unit of 1,000 grams if you're going to do that let's move along here and let's talk about instead of kilo this is a pretty big unit kilo is large right it sort of sounds large even what about senti that's another that's another unit or another prefix and senti is 10 to the minus 2 see this is 10 to the 3 for 1,000 10 to the minus 2 is the same as 0.01 which is the same as 1 over a hundred so for those of you who aren't sure about the algebra when you have something raised to a negative power like this it's exactly the same thing as is saying 1 over 10 squared that's what that means 1 over 10 squared is 1 over a hundred so when we say senti it's the same as 10 to the minus 2 which is the same as 1 over 100 which is the same as point on 1 these are all the same thing I'm just writing them down to get to show you here so when we say 1 centimeter which you probably already knows about that big it's much smaller than a meter it's 1/100 of a meter so it's a unit that's much smaller than a meter because it's convenient a lot of times if I'm measuring something that big to talk about centimeters it would be cumbersome to talk about kilometers or even meters if I'm talking about something small all right so just to give you an example if I were going to measure something like you know this big here it would make a whole lot more sense for me to talk about centimeters than for me to talk about kilometers because that's a smaller unit there so it's 1/100 here now continuing on in the progression here let's talk about millimeters or milli let's talk about milli the prefix milli means 10 to the minus 3 which is the same as 0.001 which is the same as 1 over 1,000 so if I were gonna use this guy it would be you know 1 millimeter right is equal to let's say 1 over 1000 of the meter that's what this is saying we can read this millimeter you can read the milli as one over a thousand which is the same thing when we talked about kilometer replacing kilo with 1000 so you can see there's these different prefixes some of them some of them like kilo mean large multiples because we're talking about something really far away maybe we want to talk about the distance to another planet we would talk about kilometers or even something larger but if we're measuring the width of a human hair we're not gonna use kilometers or whatever we might use millimeters or we might even use nanometers or micrometers which are even smaller little divisions but you see how everything is done everything is a nice power of 10 kilo is a thousand senti is one over a hundred milli is one over a thousand so the whole thing progresses like that now let me write a little table for you just to help you out you're gonna probably find this in your book but just to help you out 10 to the 9 is Giga all right we represent that with G you might have heard of gigawatts gigawatts of electricity that's a huge unit of power that's 10 to the 9 right that's that's a lot of zeros here that's like a billion of something that's Giga then you have 10 to the 6 which is mega which we abbreviate with M so here we might have just giving an example we might have a Giga gram of something or here we might have a mega gram of something right here we have 10 to the power of 3 which is 1,000 we talked about that that's kilo and we appreciate that with K so we might be talking about kilometers right now if we get down smaller then we might have 10 to the minus 1 which is deci which is d so it might have a decimeter for instance now you don't honestly use des it very much at all I'm just putting it here for completeness you probably you might see it in a book 10 to the minus 2 centi we talk about C of something so it might have centimeters as an example then we go 10 to the minus 3 for Milli we might have a millimeter so we've talked about those but you know I keep talking about in terms of meters but this could be milli second probably a lot of you have heard about that when you're timing a swimmer you might measure his results in milliseconds because you're really interested in how how fast he crosses the line right so you might have the minutes the seconds and maybe the milliseconds after that to kind of as a fractional between seconds right so these things can be applied to any of the units that's why we're talking about them here in general if you go even smaller you get to 10 to the minus 6 which is micro all right now micro you can't use em again a small M this is capital M this is small M you can't use em again from micro so you actually have this little symbol which is a Greek symbol mu all right so you kind of go up and then get it I put a little U on it that's basically what you have here and so you might talk about micrometers or microns the way of talking about that 10 to the minus 9 we call nanometers right and we use the letter n so that's nanometers and this is kind of a popular culture nanotechnology what does that mean doesn't mean anything big nanotechnology means incredibly tiny or maybe an iPod nano that's really really tiny so that prefix and nano means really really small one billionth of a meter is what that is and finally the last one I'll put on here is 10 to the minus 12 which is pinko we use the prefix P maybe you have a picosecond picosecond is incredibly tiny it's even you know it's even less than a billion it's 10 to the minus 12 so these are incredibly small fractions of a meter a meter being what you're familiar with about this big right so I don't think I have to say this but just for completeness this scale as we go this way we go to larger units so this is the metric system in a nutshell this is the cliffnotes version of the metric system we have prefixes like Giga and mega and kilo to represent large units of a meter or a second or a gram or whatever kilogram megagram Giga gram okay can do that and then once you get smaller to smaller divisions of your base unit you have deci which you don't use very much and then you have senti centimeters millimeters and micrometers and nano meters Pico meters but they all apply to seconds they all apply to time length mass anything in the metric system alright so now that we know what the metric system really is right and now you kind of know how to interpret it if somebody tells you they have two centimeters or soo centigrams or two milligrams of something if you get a the drugstore to tell you two milligrams of a certain drug every hour you'll know that that's a fractional of a gram that's what that is now that we understand that I'm going to teach you truthfully from the bottom of my heart seriously one of the most important things that I have ever learned in all of my math and science studies and I learned it you know I guess I was in high school I had a very good teacher who taught us this and it honestly has saved me all throughout engineering all throughout graduate school it's something I constantly use and here's the deal when you try to convert units you might be going from kilometres to micrometers right you might be going from Giga you know Giga meters to Pico meters and if you're not sure what to do you might know what the conversion factor is between these two things but until you get some practice you may not know how to set it up do you multiply by a thousand to get what you're looking for or do you divide by a thousand now you can mentally do the gymnastics and figure it out but early on when you're getting used to this stuff that's kind of complicated in it you can lead yourself down the wrong path easily so what we're going to do here is a few quick simple examples of the unit conversions to show you how this works well let's go ahead and do that so what if you wanted to convert what if you wanted to convert 500 meters to the unit of kilometers so we know what the unit what we know how far we have here we have 500 meters of something but we don't want to express it as meters I want to express it as how many kilometers do I have so what you need to realize is that you you know the conversion factors in the metric system that's really nice is that a lot of times you know what the conversions you don't have to memorize what it is if you were in the English system you would you might need to know that how many feet are in a mile you know 5,280 feet are in a mile that's a weird number it's nothing that's a nice magical round number how many inches are in a foot there's twelve inches in a foot okay great that's not a nice round number you have to remember a lot of those things right the metric system everything is a nice multiple of ten so it's easy to remember that in one kilometer is equal to one thousand meters how do you remember that because the prefix kilo means 1000 one kilo meter 1000 meters that's what it is if you memorize these prefixes which are going to do naturally as you study any of this stuff then this becomes important so you know what the conversion factor is to go from back and forth but in the beginning here you're not really sure do I multiply or divide by a thousand and this is a super simple problem I'll give you that so a lot of you may look at this and know what to do but I guarantee you as you get farther in chemistry and you start working with density and grams and later on moles and molarity and cubic feet and other things and cubic meters as we start doing these things then it's going to become really really useful what I'm about to show you how do we convert these two things first thing you do is write down what you know 500 meters that is what you know so you write that down always start with what you know do not start with the conversion factor so you write down what you know you draw a horizontal line here and a vertical line here so you're kind of doing it like a little almost like a tic-tac-toe or something so you draw this line here in this line here the next thing you want to do is you want to write your conversion factor that you have right here this is sort of like a fraction bar a giant fraction bar we'll talk about that here in a minute now what we know is that one kilometer is equal to one thousand meters so what we want to do is write it like this we want to write it like this one kilometer is equal to one thousand meters now we want to write it this way because what we're going to do is we're gonna treat this like a fraction because it is a fraction really this is like a fraction bar so you see how we have meters on the top and meters also on the bottom here what this allows us to do is sort of cancel the meters with the meters in effect what they're doing is they're dividing out it's like you know anytime in a fraction if you have five divided by five they divide out they give you one well here we have meters divided by meters so the unit's cancel like that they sort of disappear so the final unit that we're going to have is not going to be meters because these have canceled the final unit we're going to have is kilometers which is what we want we're trying to convert the kilometers so what we do here is we again this is we treat it like a fraction so what we have is five hundred times one we're multiplying by one because these are both on top we take the result of that which is 500 and we divide it by one thousand five hundred times one divided by one thousand it's going to give you a zero point five zero point five what well the only unit remaining that hasn't cancelled with anything is kilometre so we have kilometers this is the answer now this is something that you could do in your head because if you know I made up an easy problem on purpose so you could follow it 500 meters if you know that a thousand meters is a kilometer then 500 meters must be half a kilometer that's really easy but I guarantee you I could generate a problem that when involved in nanometers or picoseconds and I would confuse you on what to do but if you set it up this way where your units cancel leaving you with the unit you're trying to convert to you will always get the right answer and you won't even have to decide to multiply or divide that's what your what the real power of it is you don't even have to think about the logical thing to do to multiply or divide all you need to do is set it up properly so that in the end you'll get the unit you want now let me show you one more thing real quick before we move on to the next problem what if we set it up the other way 500 meters now the next thing we need to do is write our conversion factor let's just say you take a guess and you wrote it this way 1,000 meters is equal to one kilometer now we're getting ready to do your stuff here and you would look at this and you would try to cancel it you would notice K meters and kilometers they don't cancel because these are different units now these guys are the same on top but they only cancel if they're in the top in the bottom they only cancel if they're on the top at the bottom so if you accidentally wrote it this way you would immediately catch your error because you would look here and you would say kilometers doesn't cancel with anything else so I can't do anything so this is totally wrong so you would discount that right away because you're not left with the unit you're trying to convert to all right now what if you were trying to convert for centimeters to meters right so you would do it exactly the same way you start with what you know four centimeters draw you a little horizontal and vertical bar and next you have to write down the conversion factor you know how many centimeters are in a mirror there are 100 centimeters in a meter so you write it this way 100 centimeters in one liters why do you write it that way it's because when we write it this way as opposed to if it were flipped the centimeters will cancel with the centimeters so they're gone the only thing I'm going to have left is meters which is what I'm actually trying to count it to convert to 4 times 1 is 4 4 divided by 100 is going to give me 0.04 the unit is meter because that's the only thing left over that's what I'm trying to convert to and we'll do a few more little simple problems but I guess I'm just gonna cut to the punchline here this this little method works for anything any unit at all anything physics chemistry math biology anything at all with the unit if you're talking about meters per second and you're trying to convert it to kilometers per day you can do that if you're trying to take grams per cubic centimeter and convert it to kilograms per cubic kilometer you can do that all with this method here and you don't have to think about what to do you just set the unit's up so that everything cancels make sure your conversion factors are correct I'll spits the correct unit because that's the way you've set it up now let's say we're gonna do something a tiny bit more complicated not really really complicated but a little bit more what if I were going to convert for centimeters instead of two meters what if I wanted to know how many millimeters that was right so a lot of you looking at this may not know what to do some of you probably do know what to do but a lot of you I bet you don't because you have four centimeters and unless you're good with the metric system you may not know off the top of your head how many centimeters or how many millimeters are actually in in a centimeter a lot of you may know that watching that watching this right now but some of you don't so I'm not going to tell you because I'm gonna pretend that we don't know but we don't know how many let's pretend we don't know how many millimeters are in a centimeter but what we do know is how many we know um but write down what we know what we do know is 1000 millimeters is equal to one meter and we also know that 100 centimeters is equal to one meter but this isn't exactly what we're trying to go because we're actually trying to go from centimetres to millimetres but we we don't actually have a conversion factor you may know okay right now watching is you may know how many are in there but um we're gonna pretend that we don't know but what we do know is how many millimeters are in a meter and how many centimeters are in a meter so let's just use what we actually have here and I'll show you the power of this method if you write it this way 100 centimeters in one meter right I can continue this guy as many times as I need and I can write it like this one meter is 1000 millimeters now why did I do that because right here centimeters cancels with centimeters and meters also cancels with meters anything in the top is going to cancel with the same unit in the bottom and you can extend this unit conversion thing as long as you need to to get the units to cancel in a way that you need them to cancel so you've cancelled the centimeters you've canceled the meters all you have left is millimeters so the way you do this is 4 times 1 gives you 4 4 divided by 100 take that multiply by a thousand divided by 1 so basically what you're doing is everything is multiplied together in the top and then you divide by everything on the bottom that's all you're really doing here the answer you're going to get is 40 millimeters 40 millimeters now for those of you that did know 4 centimeters how many millimeters are in a centimeter a lot of you probably already knew that 1 centimeter contains 10 millimeters this is not something I've told you this is something that some of you may know just because you may have worked with the metric system a little bit longer and that's okay so if you happen to know that that's your conversion factor and you know that to be a fact then and look at what I've done I've flipped it wrong upside down it's a good example of how you can catch your mistakes right so what we know is 1 centimeter is 10 millimeters all right the reason I caught my mistake is because I look down to cancel my units and I couldn't do it but now I can cancel centimeters with centimeters so all I have to do is do 4 times 10 course divided by 1 I'm going to get 40 millimeters but you see the power of this I mean I don't know if it dawns on you yet but it should because it's very powerful I've done the problem two different ways one way I knew the direct conversion factor between the two things I was trying to do and I get the right answer here I didn't really even know the direct conversion factor all I knew is two different conversion factors in other words I connected centimeters to meters and then I connected meters to millimeters so you can sort of think about it as it connect the dots if I'm trying to convert from one unit to the other I don't need to know a direct conversion factor between the two if I know it that's great wonderful use it but if you don't just as long as you connect the dots with your conversions from point A to point B you'll always get the right answer here we went from centimeters to meters meters to millimeters and we get the right answer I'm telling you that as you do this more you know in chemistry and other classes it will save you on so many occasions because it really prevents you from getting in the mental entanglement of figuring out what to do now what if I gave you a problem and I said given one inch is equal to two point five four centimeters right that's something that I haven't told you up until now but it's true if you measure an inch it's 2.54 centimeters and what if I asked you to convert two inches to centimeters how would you do that well I've given you the conversion factor so all you do is you start with what you know two inches and now we apply our conversion factor one inch is equal to two point five four centimeters the way I write it is one inch is 2.54 centimeters I don't flip it over because if I flipped it over I wouldn't have any units canceling anywhere but here I have inches cancel with inches which leave me only with centimeters two times two point five four divided by one obviously is five point zero eight centimeters and that's the answer and that's you know that's basically it I'm just giving you a few really easy examples here I'm not gonna go into density calculations I'm not gonna go into other things because really we're going to use this in this technique here all throughout the course in almost every problem we do you'll see something like this because we'll be setting up our units and I'll also tell you if you want more of a background in SI system unit conversions things like that go look at the unit conversion tutor it's four hours of all of this stuff giving you lots of different units lots of different examples I think what I've shown you here is here here is good enough to kind of get you primed and as we go through the course we'll do it together and you'll learn and I think it'll be okay but for those who want a little extra go take a look at that because it's all in there all right now one more thing I want to talk about before we leave here is scientific notation it's something a lot of you may have already seen before maybe it's totally completely new to you here but it's a very simple concept don't let the name scare you scientific notation oh my gosh it must be so incredibly difficult it's very easy actually well it basically amounts to is numbers are great I can represent you know 127 apples if I want to and that's easy it's just three digits hundred twenty seven apples but what if I had you know five billion apples what if I had five billion three hundred and forty two million five hundred ninety two thousand three hundred ninety four apples well I could write all those digits out but that gets really annoying after a while what if I'm even doing something larger what if I'm measuring the number of meters or kilometers to the nearest planet or to the Sun talking millions or even billions of kilometers away so it's just a lot of digits to write over and over again so there's a shorthand way of writing very large numbers and also very small numbers you know if you're looking at the the size of a molecule you might be talking about ten to the minus nine or very micrometers or something like that so we use a different way of writing very large numbers and very small numbers and that's called scientific notation the easiest way to explain what it is is just to show you what if I have the number two three seven six 2376 and I wanted to represent that in scientific notation the way I would do it I would keep the same digits two point three seven six digits are the same but I put a decimal point after the first digit and I multiply by 10 to the power of three why do I multiply by the power of three it's because if I put the decimal here then when I multiply by 10 to the 3 basically you move the decimal as many times as it is indicated in this exponent so I move the decimal three times one two three 2376 so it's it's basically a shorthand way of writing that and you might look at this and say well this looks shorter I mean what's a big deal about doing this well as you use this more you'll understand the advantages of it what if I have a hundred and fifty one and I wanted to convert that to scientific notation it would be one point five one times ten to the power of two now where this comes in handy a lot of times is what if I were measuring the distance to you know the Sun or something what if it came out to two three seven four nine three eight seven two one and that's a number of kilometer so that's a lot of digits right obviously every digit is important but probably mostly what you're interested in is is the kind of general you know order of magnitude of it the last digits over here yeah they're important to be exact but really when you're talking about the distance to Mars you may not care about every last digit there so the way to really handle that is you could write this as two point three seven four nine let's say you wanted to take it out to here but then you would multiply by 10 to the one two three four five six seven eight nine times ten to the nine because in scientific notation the decimal is here but when I multiply by 10 to the nine it's just moving the decimal let me ask you something what happens when you multiply something by 10 let's say you have four and you multiply by 10 what happens well that's 40 right all you've done and see there's a decimal point here you can't see it because it's four point zero but the decimals here if I multiply by ten I move the decimal on the other side of that little invisible zero here making 40 what happens if I multiply by 4 times 100 right well I'm gonna get 400 what happens if I multiply 4 times 1000 right well I'm gonna get 4000 you see every time I multiply by a bigger you know multiple of 10 like this I'm just moving the decimal point one spot over to the right that's all I'm doing so if the decimal is here I move it one spot I get 40 the decimals here I move it two spots I get 400 decimals here I move it three spots I get 4,000 so this is 10 this is 10 squared this is 10 cubed right so this is 10 to the ninth just means move the decimal place nine spots that direction that's all it means so all you have to do when you're looking at scientific notation of something is look at this exponent to the right that many spots now yes this answer that you get is not going to be exactly the same as this because I've truncated I've left off some of the digits but when you're talking about really really long distances that's good enough for most cases all right now let's look at a different example what if we have something small zero point zero zero two three how would I write that in scientific notation zero zero two three well if I use positive numbers to make me move the decimal point to the right and then when I mean ain't going to end up doing is using negative exponents to shift the decimal point the other direction so the way you do it is you look at your first numbers here here have the first number other than zero is two and three so we have two point three always put the decimal after the first digit times 10 to the - pretend you have a decimal point here you're going to move the decimal to the left one two three spots 10 to the minus three and this is really where it shines also because you know this is kind of ugly zero point zero zero two three what if you have five zero zero point you know zero zero zero two three well this is going to end up being shorter too right and it's just something you're gonna have to learn and you'll see a lot of your problems that will Express number of grams in terms of scientific notation so you have to understand what if we have three point one two times ten to the minus five how do we convert that back to a regular number well we have a negative decimal here so the my advice to you is just to write down your numbers three one two stick your finger right here where the decimal is right here and then you're gonna have to shift your shift it to the left one two three four and put a decimal point here and just check yourself put your decimal point here and shift it to the left five one two four five and you could put a leading zero here if you wanted to zero point zero zero zero zero three one two and I can't tell you how many I've actually written a number and stuck my finger there and counted the decimals and you're just going to have to do it that's just the way it is but if it's a the the the critical thing to pull out here is if your scientific notation has a positive exponent you're shifting the decimal point to the right you're making a large number if it's a negative exponent you're shifting the decimal to the left which is means you're making a really small number one final example is how would I write that as a regular number well I just write five four I stick my finger there and I start writing zeros 1 2 3 4 5 I check myself I stick a decimal here and I move it six butts to the right 1 2 3 4 5 6 and that's what I came up with so frequently you might kind of put one less zero or whatever check yourself and then you have to add a zero to make sure but this is what this means 5 point 4 times 10 to the 6 is the same thing as 5,400,000 and that's a good intro to scientific notation and again I'll just say it one more time if you need more practice with scientific notation if you aren't quite sure if this is enough for you go look at the unit conversion tutor it has a whole section on scientific notation with a lot of different problems I think again this is enough to get you by especially if you've seen it before and we're going to be working with it so much that you'll probably get really comfortable with it here here quickly but if you need some extra help unit conversions there for hours of concentrated coverage of that so we have covered another section we've talked about the really important topic of units and unit conversions and chemistry we've talked about the SI system we've talked about the metric prefixes we've talked about what they mean we've talked about converting units and showing you I don't really want to call it a trick it's not my trick a lot of people use it but unfortunately a lot of books don't show you how to do unit conversions in this way and I'm telling you that this will save you so much time when you get to more complicated units you know your mind will just spend with how easy it is after that occasionally you might bump into one of your friends that has never seen this before and it'll save their you know save from pulling their hair out you know when they're doing their homework as well we've also talked about scientific notation measuring or I should say writing down law numbers and also very small numbers a lot of your problems I hope you'll see the number of grams or the number you know or the the distance of something or the amount of something in terms of scientific notation so you just need to know it's just a different way of writing a large number and a small number and you can input scientific notation directly into your scientific calculator or your graphing calculator so you just type it in just like you see it and you can use it there my name is Jason I hope you've enjoyed this section I hope you've learned a little something here stick with me I'll take you step-by-step here in the next few sections we're gonna start talking about some real chemistry putting elements together to create compounds and then going and looking at chemical reactions but we need to do things one step at a time the most important thing you can do for yourself is go in order watch everything in order absorb everything if you try to skip around too much then you're just going to be confused for no good reason I'm Jason practice your problems practice your unit conversions I promise you it'll save you a ton of time on your homework and on your exams

Channel: Math and Science

Views: 1,048,096

Keywords: unit converter, unit conversion, chemistry, physics, scientific notation, metric system, si system, unit conversion chemistry, unit conversion physics, unit conversion math, unit conversion metric system, scientific notation chemistry, scientific notation explained, metric system conversion, metric system explained, how to convert into scientific notation, dimensional analysis, significant figures, conversion, units, convert, math, analysis, mass, time, length

Id: W_SMypXo7tc

Length: 40min 35sec (2435 seconds)

Published: Thu Apr 19 2018