Which conversion factor do you use first to calculate the number of grams of FeCl3 produced by the reaction of 30.3 g of Fe with C12? (What would be your first step in the bracket/train tracks?)
2Fe + 3Cl2 --> 2FeCl3

1) 1 mol Fe/ 55.845 g Fe
2) 3 mol Cl2/ 2 mol Fe
3) 35.453 g Cl2/ 1 g Fe
4) 162.2 g FeCl3/ 2 mol FeCl3

3 mol Cl2/ 2 mol fe

Explanation:

"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"

може ли да зареждате повече информация, моля