Question

If you were helping a friend do stoichiometry problems, what would you tell them about how they might use subscripts and coefficients in their problem solving? Use Sentence(s).

Answer 1

Im not sure if this will help but... your subscripts in a balanced equation are used to calculate the molar mass of the compound. And your coefficients are used to get the ratios. so for example we have this balanced equation
Be3N2 + 6H2O= 3Be(OH)2 + 2NH3  and you have to find the molar mass of 6h2o, you need to multiply the subscript by the atomic mass and then add them together to get the overall molar mass.  * 2(1.01) + 16.00= 18.02 g/mol
and if a question wants to know the limiting or excess regent you would use the coefficients to find out the ratio between the compounds.
 

Answer 2

Answer: By using law of conservation of mass.

Explanation:

A balanced chemical equation always follow law of conservation of mass.

This law states that mass can neither be created nor be destroyed but it can only be transformed from one form to another form. This also means that total number of individual atoms on reactant side must be equal to the total number of individual atoms on the product side.

The chemical reaction for the formation of water follows the equation:

$2H_2+O_2\rightarrow 2H_2O$

Total mass on reactant side:  $[2(2\times 1)+(2\times 16)]=36g/mol$

Total mass on product side:  $[2((2\times 1)+16)]=36g/mol$

Hence, by using law of conservation of mass.