Calculate the number of moles of each element, given the number of atoms. If you need to make a number superscript, put a ^ in front of the number. For example, 2.45 x 1022 would be written as 2.45 x 10^22. 5.73 x 1024 carbon atoms =
2.06 x 1020 copper atoms =
9.32 x 1026 sulfur atoms =

"you start with 15.67 g mgco3-xh2o, when heated and all the water is removed, you are left with 7.58 g mgco3 only.

therefore, you had 15.67 - 7.58 = 8.09g h2o  

moles of each :

7.58g mgco3 = ? moles = 7.58g / 83.4g/mole = 0.09moles  

8 09g h2o = ? moles = 8.09g / 18g/mole = 0.44moles  

molar ratio between the two by dividing both numbers by the smallest number :

0.09 / 0.09 = 1  

0.44 / 0.09 = 4.8  

mgco3-5h2o"

there are two significant figures.