Answer:
The correct answer is 2.6 g C₉H₈O₄
Explanation:
-First we have to write and to balance the chemical equation:
C₇H₆O₃ + C₄H₆O₃ ⇄ C₉H₈O₄ + C₂H₄O₂
-Then, we calculate the molecular masses of reactants and products:
1 mol C₇H₆O₃= (12 g/mol C x 7) + (1 g/mol H x 6) + (16 g/mol O x 3)= 138 g
1 mol C₄H₆O₃= (12 g/mol C x 4) + (1 g/mol H x 6) + (16 g/mol O x 3)= 102 g
1 mol C₉H₈O₄= (12 g/mol C x 9) + (1 g/mol H x 8) + (16 g/mol O x 4)= 180 g
1 mol C₂H₄O₂= (12 g/mol C x 2) + (1 g/mol H x 4) + (16 g/mol O x 2)= 60 g
The mass balance is correct because:
mass reactants = mass products
138 g + 102 g = 180 g + 60 g
240 g = 240 g
-Now we use the masses from the chemical equation to calculate how reactant we need. We know that 138 g of salicylic acid (C₇H₆O₃) react with 102 g of acetic anhydride (C₄H₆O₃). So, the grams of acetic anhydride we need to react with 2 g of salicylic acid will be:
138 g C₇H₆O₃------------------- 102 g C₄H₆O₃
2.0 g C₇H₆O₃ -------------------- x= (2.0 x 102)/138 = 1.48 g C₄H₆O₃
If we compare, the amount of C₄H₆O₃ we need (1.48 g) is lesser than the amount we have (8 g), so C₄H₆O₃ is the excess reactant and C₇H₆O₃ is the limiting reactant.
- Finally, <u>we use the limiting reactant</u> to calculate the theoretical yield in grams of C₉H₈O₄. From the chemical equation, we know that 138 g C₇H₆O₃ yield 180 g of C₉H₈O₄. We have 2.0 g, so:
138 g C₇H₆O₃------------------- 180 g C₉H₈O₄
2.0 g C₇H₆O₃ -------------------- x= (2.0 x 180)/138 = 2.6 g C₉H₈O₄
