Given the following equation, determine the amount of HCl (in grams) that is produced with 90.0 g FeCl3. 2 FeCl3 + 3 H2S → 6 HCl + Fe2S3

Question

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Answer 1

First, write the correctly balanced equation (which is actually given to you).

2FeCl₃ + 3H₂S ==> 6HCl + Fe₂S₃

Next, note the stoichiometry, i.e. coefficients, i.e. mole ratio of each compound. You see that it takes 2 moles FeCl₃ to produce 6 moles HCl (assuming that H₂S is not limiting).  Since no mention is made of H2S, you can assume it is present in excess.

Next, convert 90.0 g FeCl₃ to moles and calculate moles of HCl produced.

90.0 g FeCl₃ x 1 mole FeCl3/162.2 g = 0.5549 moles FeCl₃

moles HCl formed = 0.5549 moles FeCl₃ x 6 moles HCl/2 moles FeCl₃ = 1.665 moles HCl formed

Finally, convert moles HCl to grams HCl.

1.665 moles HCl x 36.5 g/mole = 60.8 grams HCl (to 3 significant figures)