6
lesson pretestMultiple Choice

Pretest

Question 6 • Chemistry

Salicylic acid (C7⁢H6⁢O3) reacts with acetic anhydride (C4⁢H6⁢O3) to form acetylsalicylic acid (C9⁢H8⁢O4). 2 cap c sub 7 cap h sub 6 cap o sub 3 aq plus cap c sub 4 cap h sub 6 cap o sub 3 aq rightarrow 2 cap c sub 9 cap h sub 8 cap o sub 4 aq plus cap h sub 2 cap o l What is the limiting reactant if 70 point 0 g of open paren cap c sub 7 cap h sub 6 cap o sub 3 close paren and 80 point 0 g of open paren cap c sub 4 cap h sub 6 cap o sub 3 close paren react?

Answer
A
acetylsalicylic acid
B
water
C
salicylic acid
D
acetic anhydride

Explanation

The balanced equation requires 2 moles of salicylic acid for every 1 mole of acetic anhydride. The amounts are 70.0 g ÷ 138.12 g/mol ≈ 0.507 mol salicylic acid and 80.0 g ÷ 102.09 g/mol ≈ 0.784 mol acetic anhydride. Using all 0.507 mol of salicylic acid would require only about 0.254 mol of acetic anhydride, so salicylic acid runs out first. The limiting reactant is salicylic acid, choice C.

AI-written and checked against the verified answer.

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