Answer to Question #261015 in General Chemistry for Rine

Question

Zinc and HCl react to form ZnCl2 and hydrogen gas. How many grams of H2 can be produced if 4.25g of Zinc react with 25 mL of 3.00M HCl?

Answer 1

25 mL x (1L/1000 mL) x (4 mol HCl/1L) x (1 mol Zn/2 mol HCl) x (65.38 g Zn/1 mol Zn) = 3.269g = ~ 3.3g of Zn

Parts explained

25 mL x (1L/1000 mL) x (4 mol HCl/1L) = 0.1 mol of HCl that reacts with Zn. Note: (1L/1000mL) is conversion factor to change mL to L

25 mL x (1L/1000 mL) x (4 mol HCl/1L) x (1 mol Zn/2 mol HCl) = 0.05 mol of Zn that reacts completely with 0.1 mol of HCl. Note: From the balanced equation, 2 mol of HCl reacts with 1 mol Zn, thus we use (1 mol Zn/2 mol HCl) as conversion factor

(65.38 g Zn/1 mol Zn) = Molar mass of Zn, used to convert moles to grams.