chemistry mole ratio

Question

For the reaction 2 HCl(aq) + K₂SO₃(s)  H₂O(l) + SO₂(g) + 2 KCl(aq) answer the following questions.

1. What is the mole ratio of HCl : K₂SO₃ in the equation? 
2.  3:1
3.  2:1
4.  1:1
5.  1:2
6.  1:3
7.  2:3
8.  3:2
9. How many grams of K₂SO₃(s) would be required to react completely with 26.5 mL of 3.0205 M HCl? 

Answer 1

(1). Simply look at the coefficients in the balanced equation. The coefficient for HCl is 2 and that for K2SO3 is 1, so the mole ratio is 2 : 1

(2). Find moles of HCl and then since the mol ratio of HCl : K2SO3 is 2:1 (as determined above), we can find moles K2SO3 and then grams of K2SO3.

moles HCl = 26.5 ml x 1 L/1000 ml x 3.0205 mol/L = 0.08800 moles HCl

moles K2SO3 = 0.0800 mol HCl x 1 mol K2SO3 / 2 mol HCl = 0.0400 moles K2SO3 needed

mass K2SO3 needed = 0.0400 mol K2SO3 x 158 g/mol = 6.32 g K2SO3 needed (3 sig. figs.)