Practice Question # 6 Gram to gram mole ratio stoichiometry

Question

Copper I iodide, CuI, is not stable enough to last long in storage, so it is generally made just prior to use. It can be prepared from copper sulphate and hydriodic acid by the following reaction. If 34.56 grams of HI is used, calculate the number of grams of each of the products that are produced.

Answer 1

First, it is best to write the correctly balanced equation for the reaction of interest.

Cu₂SO₄ + 2HI ==> 2CuI + H₂SO₄

moles HI used = 34.56 g HI x 1 mol HI/128 g = 0.27 moles

Assuming copper sulfate is not limiting, the following will be the grams of each product produced:

CuI:

0.27 moles HI x 2 mol CuI/2 mol HI x 190.5 g CuI/mol = 51.44 g CuI

H₂SO₄:

0.27 moles HI x 1 mole H₂SO₄/2 mol HI x 98.08 g H₂SO₄/mol = 13.24 g H₂SO₄