A) 67.5 g
B) 9.45 g
C) 6.75 g
D) 94.5 g
Correct Answer: A
Solution :
Key Idea: Molarity \[=\frac{\text{moles}\,\text{of}\,\text{solute}}{\text{volume}\,\text{of}\,\text{solution}\,\text{in}\,\text{L}}\] \[\text{=}\,\frac{\text{mass/molecular}\,\text{mass}}{\text{V}\,\text{in}\,\text{L}}\] Given \[\text{molarity =}\,\text{2}\text{.5}\,\text{M}\] \[\text{Volume}\,\text{=}\,300\,mL=\frac{300}{1000}L\] Molecular mass of oxalic acid \[{{(COOH)}_{2}}\] \[={{(12+16\,\times 2+1)}_{2}}=90\] \[2.5=\frac{mass/90}{300/1000}\] or \[2.5=\frac{mass}{90}\times \frac{1000}{300}\] \[mass=\frac{90\times 300\times 2.5}{1000}\] \[=67.5\,g\]
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