Question

How many moles of hydrogen gas will form 1.35 L of a 2.75 M Hcl solution reacts?

Answer 1

1.86 moles of hydrogen gas. Since what the HCl is reacting with hasn't been mentioned, I'll assume zine. In that case, the balanced reaction is Zn + 2HCl ==> ZnCl2 + H2 So for every 2 moles of HCl used, 1 mole of hydrogen gas will be generated. So let's figure out how many moles of HCl we have and then divide by 2. Molarity is defined as moles/liter. So a 2.75 M HCl solution has 2.75 moles of HCl per liter. So the total number of moles we have is: 2.75 mole/L * 1.35 L = 3.7125 mol And since we get 1 mole H2 per mole of HCl, we get: 3.7125 mol / 2 = 1.85625 mol Rounding to 3 significant figures gives us 1.86 moles of hydrogen gas.