GRE Subject Test: Chemistry : Gravimetric Analysis

Study concepts, example questions & explanations for GRE Subject Test: Chemistry

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Example Questions

Example Question #1 : Analyzing Solids

Household vinegar contains the organic compound acetic acid with chemical formula, \(\displaystyle CH_{3}COOH\). If a \(\displaystyle 10.00 g\) vinegar sample contains \(\displaystyle 0.1024\ moles\) of acetic acid, calculate the percent (mass/mass) of the \(\displaystyle CH_{3}COOH\) in the vinegar sample.

Density of vinegar is the following:

\(\displaystyle CH_{3}COOH=1.05\frac{g}{mL}\)

Possible Answers:

\(\displaystyle 12.8\%\)

\(\displaystyle 75\%\)

\(\displaystyle 61.5\%\)

\(\displaystyle 3.3\%\)

Correct answer:

\(\displaystyle 61.5\%\)

Explanation:

Convert the moles of \(\displaystyle CH_{3}COOH\) to grams:

\(\displaystyle 0.1024\ moles \times \frac{60.05g}{mole}=6.1491g\ CH_{3}COOH\)

To calculate the percentage of \(\displaystyle CH_{3}COOH\) in the vinegar we need to use the following formula:

\(\displaystyle \%CH_{3}COOH=\frac{grams\ of\ CH_{3}COOH}{grams\ of\ vinegar}\)

Therefore, 

\(\displaystyle \frac{6.15g}{10.00g}\times 100=61.5\%\ CH_{3}COOH\)

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