For each of the following unbalanced equations, calculate how many moles of the second reactant would be required to react completely with 0.512 moles of the first reactant.

Question

Co(s) + F2 (g) ----> CoF3 (s)

??? Moles F2

Al(s) +H2SO4(aq) ------> Al2(SO4)3 (s) + H2 (g)

??? Moles H2SO4

K(s) + H2O (l) ------> KOH(aq) + H2 (g)

???? moles H2O

Answer 1

The first step for these problems is to balance out each equation. For the first one that means the following:

2 Co(s) + 3 F2 (g) ----> 2 CoF3 (s)

We see that for every 3 moles of F2, we use 2 moles of Co, a mole ratio of 3 moles F2 / 2 moles Co. To answer the question we have to multiple the moles of F2 by the molar ratio or in this case the inverse molar ratio (2/3). The answer is therefore 0.512*2/3 = 0.341.

The rest of the questions can be answered in a similar way. Let me know if you need to meet to clarify anything.