How many grams of HCl can be prepared from 2.00 mol H2SO4 and 150 g NaCl?

Question

2 NaCl(s) + H2SO4(aq) ----> 2 HCl (g) + NaSO4(aq)

Answer 1

Watch out! they are trying to fool you by giving the moles of H2SO4 hoping you will use that to determine amount of HCl produced without checking something important!

To get the right answer; first, determine the limiting reagant:

You have 2 moles of sulfuric acid since they told you that, but we need to see if there is enough sodium chloride to react with it. To do this, we need to divide the weight of NaCl provided by the molar mass for NaCl:

150g/(35.45 + 23)g/mole = 2.57moles

Note that it takes 2 NaCl's to react with one H2SO4! So, if we have 2 moles of H2SO4 we would need 4 moles of NaCl to react all of it; there is not enough, so some H2SO4 will be left over. Since NaCl is the limiting reagant, we will use it for the calculation: To get grams of HCl produced, we just need to take the number of moles of sodium chloride x the ratios from the balanced equation (for HCl & NaCl) x the molar mass for HCl:

2.57mole x (2/2) x (1.01 + 35.45)g/mole = 93.7g of HCl