5
lesson pretestMultiple Choice

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Question 5 • Chemistry

A 115.0-g sample of oxygen was produced by heating 400.0 g of potassium chlorate. 2 KClO sub 3 rightarrow 2 KCl plus 3 cap o sub 2 What is the percent yield of oxygen in this chemical reaction? Use percent Yield is equal to Actual yield over Theoretical yield times 100

Answer
A
90 point 8 2 percent
B
136 point 2 percent
C
69 point 6 3 percent
D
73 point 4 0 percent

Explanation

First find the theoretical oxygen yield using the balanced equation: 2 mol KClO₃ produce 3 mol O₂. The 400.0 g of KClO₃ corresponds to about 3.263 mol, which can produce 3.263 × (3/2) × 32.00 = 156.6 g O₂. Percent yield = (115.0 g ÷ 156.6 g) × 100 = 73.40%, so the correct choice is D, 73.40%.

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