this video will cover conversions and chemistry generally we use the metric system in chemistry and the metric system is simply a system of numbers that is based on the powers of 10 and if we look here we've got a table that gives the prefixes their meanings and how we actually can use these prefixes with an example of meters so you should take the time to memorize all of these however what I will say is that let's say kilo centi milli micro these are all pretty important and even dusty there's a lot of health professionals and a lot of concentrations in how our writ or volumes are written in deciliters so these are pretty important for you to know I would say memorize all of them but these five are particularly useful this here this symbol is called the Greek mu and it can also be written as MC for micro all right so let's take a look at what these values mean let's take a look at a sin T so for 4 measurements we have the meter and it's going to measure distance and these are metric system we've got the liter which measures volume and we've got the gram that measures mass and for temperature we've got zero degrees Celsius or Celsius temperature so these are uses of the measurements that we're taking in in in chemistry so remember we had these really large numbers and really small numbers that we use to do scientific notation well certain prefixes have a name or certain let's say certain powers of 10 have a name right so if I've got 10 to the 9 that's like Giga ooh Giga gigabytes on your phone your computer well tera bytes which everyone has now tera is actually 10 to the 12 right so when you see gigabytes and terabytes bytes are just a measurement of information so these are the same prefixes that you're used to seeing already kilo has a meaning of 10 to the 3 or 1 times 10 to the 3 so you need to know these because you will be given measurements that are going to be written as Killah meter or kilogram and you'll need to know what that Killough actually means so let's do some practice conversions using we're going to do some practice conversion using the metric system and also some conversions between the metric in English system all right so let's convert 450 milligrams to grams I also suggest that you memorize what the heck so don't just memorize 70 kilo milli you need to know what the definition is so milli is equal to the letter M and 10 to the minus 6 so when it says that we have 400 I'm sorry not 10 to the minus 6 10 to the minus 3 10 to the minus 3 so if we're going to convert milligrams to grams well we can already right 450 and if I just take that m and interchange it with the 10 to the minus 3 there I go what's my answer we can be a little fancy minute we can do a little something more how many grams do we get from 450 milligrams well if you can't remember no you have to remember I'm 90 they'll say that so what we can also say is that 1,000 milligrams are equal to 1 gram and our milligrams cancel out and we get 0.45 zero grams if we want to make sure that we have the correct number of sig figs we will make this 0.45 great I'm going to leave my scientific notation one like this because if not we wouldn't end up with the right number all right so you can do these calculations in more than one way right so but does this make sense one gram is much larger than one milligram so yes it should be a small number compared to what we start off with all right the next question says convert 0.003 76 liters to centimeters while leaders does not have a prefix in front of it so that number is what it is and I want to go to stick two meters cute don't don't don't freak out centimeters cube is equal to milliliters all right and milli remember it's 10 to the minus 3 right so one centimeter cubed is equal to one milliliter which is equal to 1 times 10 to the minus 3 liters all right so we want to know how many cube centimeters well if I had two numbers that are equal to each other I can write them as conversion factors so this could be one centimeter cubed over ten to the minus three liters for this could be ten to the minus three liters is equal to one centimeters cubed right this another way I think that's what gets confusing with conversions and metric conversions because they can be written so many different ways so if I said that there's 10 to the minus 3 liters or 1 cubic centimeters I can write that the other way and say that there are 10 to the 3 cubic centimeters in one liter right so all of these conversions are the exact same number they all represent the exact same set of numbers okay so let me do that all right so we can pick any one of these conversions that we have here however they have to be written in the right way the way that I'm going to write it is so that I can cancel out my leaders so I can cancel out my leaders right here sorry guys so I can cancel out my leaders right here so which one of these conversions are going to cancel right here I've got my leaders on top that will multiply with the leaders in these two I've got leaders on the bottom which will cancel out and this one of that leaves on the top so that's not going to work so much for me here so I could use either one of these two conversions that we have here I'll just pick one I'll say one cubic centimeter is equal to 10 to the minus three liters plug that into your calculator and you get the reading point seven six cube centimeters and if I knew you could also just move the decimal place if you are really comfortable with your powers of 10 all right one last problem ooh this one's a little bit little different and we're working with English so this is an English English to metric conversion all right so we're given we need to convert 0.090 miles to inches and there are exactly 36 inches in one yard and 17 160 yards and one mile so let's write our conversions so we've got 36 inches in one yard and that is we can write it this way one yard 36 inches and we also have 760 yards in one month and this is also equal to one mile over 17 60 yards so whenever you're doing conversions you're always going to use the conversion factor that will help you cancel out the units that you don't need so let's write down our problem we want to know how many inches there are as 0.090 miles whenever you work these problems you are base you always start with the measurement that you were given when you do your calculations never start with a conversion you'll never find the answer correctly always find the number that you were given with a unit start with that so how many inches are in 0.090 miles well my next conversion unit I've gotta get rid of miles because I'm trying to well where am I trying to go I'm going from miles to two yards two inches okay so my next conversion I need to go from miles to yards right here right so here's conversion one conversion - so which one of these conversions do I have over here that you would use to go from miles to inches I'm sorry from miles to yards well the first conversion we have is 36 inches in one yard the second conversion we have to 1760 yards at one mile whoo I think we should use one of these conversions but I want to make sure that I can cancel out miles that means miles should be on the bottom and yard should be on the top so I'm going to use this conversion so yards are on the top and we've got if we take a look here our miles will cancel and I'm left with yards all right our last conversion is now we've got to go to so this was a scene this was conversion one and now we've got to do conversion - so conversions - is from yards to inches well I've got yards here and my last conversion is either 36 inches per 1 yard or 1 yard per 36 inches I want to make sure that I'm canceling out yards so yard should be where on the top or on the bottom should be on the bottom so we're going to use this conversion and where I'll have 36 inches on the top in 1 yard so this is conversion over to notice that yards cancel out and I'm left with inches in the numerator for my answer when you plug things into your calculator you're going to put this into your account calculator we won't put inches in your calculator because it doesn't take letters all right and the answer that you get is five seven zero 2.4 now one of our previous videos we talked about significant figures well let's look back at our original number zero point zero nine zero how many significant figures were in this original answer we've got two sig figs so that means that our final answer should have two sig figs so what do we do we round off to two significant figures and we replace these last two digits with zeros they're placeholders