Question

Given the reaction:Na2S2O3(aq) + 4Cl2(g) + 5H2O(aq) --> 2NaHSO4(aq) + 8HCl(aq), how many moles of Na2S2O3 are needed to react with 0.12mol of Cl2?

Answer 1

0.03 mol `Na_2S_2O_3`

Explanation:

We can use the mole ratio to solve this problem. We will assume that we have excess `H_2O` and it won't effect our ratio. We are told that we will react 0.12 mol of `Cl_2` so we will start there.

`0.012 mol Cl_2` X `(1 mol Na_2S_2O_3)/(4 mol Cl_2)`= `0.03 molNa_2S_2O_3`

When setting up the dimensional analysis it is important that you pay attention to how many moles are in the balanced equation, that is the mole ratio.