here we're going to practice rearranging equations don't worry about the chemistry at this point in time we're just going to practice rearranging equations this problem says what is the final temperature after 840 joules is absorbed by 10 grams of water at 25 degrees Celsius we're going to use this equation Q is equal to MC delta T and T and where C is 4.184 well what do each of these mean Q is the amount of heat M is the mass in grams C is what we call the specific heat and delta T is essentially T final minus T initial we had to find the final temperature so we have to rearrange our equation to find what we need so we need to know the final temperature so let's rearrange our equation before we write down what we're given so we've got MC and delta T is T final minus T initial alright we've got to get T final all by itself hooks okay let's do this step by step if I divide both sides by divide if I divide both sides by MC I can cancel out MC on the right hand side and I end up with cube over MC is equal to T final minus T initial it t final all by itself we can add T initial to both sides and minus T and plus T they will cancel each other out so we finally have T final is equal to T initial plus Q over MC all right so let's write down what we were given so we can solve this problem what am i given I'm given that Q is equal to eighteen hundred and forty joules I'm giving my mass which is ten point Oh Gramps and I'm also given T initial which is twenty twenty-five degrees Celsius and I'm also given what C is 4.184 joules per gram degrees Celsius okay so now all we have to do is just plug and chug to get our answer T initial is 25 maybe I can plug each other to initial is 25 degrees Celsius and then plus and I'm gonna do a big parenthesis I've got eight hundred and forty joules divided by ten grams / 4.184 joules per gram degrees Celsius now when you put this into your calculator you are going to take this value this number set here and put it into your calculator 840 joules divided by a / 4.18 e4 let's make sure that our our units cancel out properly so my jewels cancel with joules grams cancel with grams and because we have Celsius in the denominator of a denominator it moves up into the numerator so when you put this in the calculator you're gonna do 840 not times / you're going to do eight forty divided by ten point o / 4.184 put that into your calculator you get that value then you add 25 the number that you'll end up with in your calculator is forty five point zero seven six now we've got to make sure that we have the right number of significant significant figures we started out with 840 joules it had two sig figs 10 grams has three sig figs and 25.0 degrees has three sig figs so our answer should only have two sig figs so it's going to be 45 degrees Celsius does that make sense we add energy into a sample so the temperature should go up if we add energy and there you have some help rearranging equations