Please help, I have no idea what i'm doing

Question

Striking a match stick on the matchbox involves the reaction of potassium

chlorate and red phosphorus with the following equation:

10 KCIO3 (s) + 3P4 (s) -> 3P4O10(s) + 10 KCI (s).

How much of each reactant will be needed to produce 105.8 g of

tetraphosphorus decaoxide (P4O10)?

Answer 1

First, you need to look at the balanced equation for the reaction taking place. It is given to you so at least you don't have to figure that part out:

10KClO₃(s) + 3P₄(s) ==> 3P₄O₁₀(s) + 10KCl

The question is asking how much of the KClO₃ and the P₄ will you need to produce 105.8 g of the P₄O₁₀?

The equation tells us that it takes 10 MOLES of KClO₃ and 3 MOLES of P₄ to make 3 MOLES of P₄O₁₀

Next, we have to convert 105.8 g P₄O₁₀ to moles by using the molar mass (283.9 g / mol)

105.8 g x 1 mol / 283.9 g = 0.3727 moles P₄O₁₀

Going back to our mole ratio of 10:3 and 3:3 we can now determine moles of KClO₃ and moles of P₄ needed

0.3727 mols P₄O₁₀ x 10 mol KClO₃ / 3 mol P₄O₁₀ = 1.24 moles KClO₃ needed

0.3727 mols P₄O₁₀ x 3 mol P₄ / 3 mol P₄O₁₀ = 0.373 moles P₄ needed

These would be the answers in moles. The question just asked for "how much", so these are the answers. IF you wanted to convert these answers to grams of each one, then you just use the molar mass of each and multiply by the moles.