AP Chemistry Lab-Based FRQ Practice

Front

What is the purpose of drying and weighing the filter paper with the precipitate three times in the experiment to determine the I⁻ content of KI tablets?

Back

To ensure all water is removed and obtain a constant mass of the precipitate.

Front

Write the expression for Kb for the carbonate ion from the reaction: CO₃²⁻ (aq) + H₂O (l) ↔ HCO₃⁻ (aq) + OH⁻ (aq)

Back

Front

Calculate the volume, in mL, of 2.000 M HC₂H₃O₂(aq) needed to prepare 100.0 mL of 0.115 M HC₂H₃O₂(aq).

Back

5.75 mL

Front

Is the experimental design sufficient to determine the enthalpy of reaction to a precision of two significant figures?

Back

No, because the beakers used have too large an uncertainty for the required precision.

Front

If a student dissolves a tablet in 55.0 mL of water instead of 50.0 mL, how will this affect the experimentally determined mass percent of I⁻?

Back

Extra water will not impact the mass percent of I⁻.

Front

Define the term 'precipitate' in the context of a chemical reaction.

Back

A precipitate is a solid that forms and settles out of a liquid mixture during a chemical reaction.

Front

What is the significance of using distilled water in chemical experiments?

Back

Distilled water is free from impurities and ions that could interfere with the results of the experiment.

Front

Explain the concept of 'enthalpy of reaction'.

Back

Enthalpy of reaction is the heat change that occurs during a chemical reaction at constant pressure.

Front

What is the role of a thermometer in measuring temperature changes in a reaction?

Back

A thermometer measures the temperature change, which is essential for calculating the enthalpy of the reaction.

Front

What does a balanced net-ionic equation represent in a chemical reaction?

Back

It shows only the species that actually participate in the reaction, excluding spectator ions.