Question

To measure the amount of citric acid (C3 H, oHn a certain candy, an analytical chemist dissolves a 16.00 g sample of the candy in 200. mL of water and titrates this solution to the endpoint with 14.2 mL of 0.340 M sodium hydroxide (NaOH) solution The balanced chemical equation for the reaction is: C3H50(CO2 H),(aq) + 30旷(ag)-→ C,HsO(CO2)|-(aq) + 3H20 (,) precipitation0 What kind of reaction is this? acid-base redox If you said this was a precipitation reaction, enter the chemical formula of the precipitate. If you said this was an acid-base reaction, enter the chemical formula of the reactant that is acting as the base. If you said this was a redox reaction, enter the chemical symbol of the element that is oxidized. Calculate the mass percent of C,H,o(CO,H), in the sample. Be sure your answer has 3 significant digits. 0%

Answer 1

Answer:

• Acid-Base reaction (the reactanct acting as a base is NaOH)

• mass percent = 1.93%

Explanation:

The reaction that takes place is:

• C₃H₅O(CO₂H)₃(aq) + 3OH⁻ (aq) → C₃H₅O(CO₂)₃⁻³(aq) + 3H₂O(l)

This is a acid-base reaction, with the citric acid acting as the acid and the sodium hydroxide NaOH acting as the base.

We calculate the moles of citric acid using the information from the titration:

• 0.0142 L * 0.340 M * $\frac{1molAcid}{3molOH^{-}}$ = 1.609x10⁻³ mol citric acid

Now we convert moles to mass using the acid's molecular weight (192.13g/mol):

• 1.609x10⁻³ mol citric acid * 192.13g/mol = 0.3092 g citric acid

Finally we calculate the mass percent of citric acid in the sample:

• 0.3092 g / 16.00 g * 100% = 1.93%