CHEM 105b Lab Exam Guide: Experiments 6-10

A series of flashcards based on the key concepts and practical applications from the CHEM 105b lab exam guide, covering acid-base equilibrium, solubility, and electrochemistry.

What is the Henderson-Hasselbalch equation used for?

To calculate the pH of a buffer solution.

What happens when pH equals pKa in a buffer solution?

The ratio [A−]/[HA] equals 1.

What is the function of a salt bridge in a galvanic cell?

Balances charges and maintains charge neutrality by allowing ion flow.

How does the pH of a buffer solution change when more buffer is added?

The pH remains the same, as it depends on the ratio, not the amount.

What is the role of bromothymol blue in an experiment with calcium hydroxide?

It acts as a pH indicator, turning yellow in acidic conditions and blue in basic conditions.

What occurs at the half-equivalence point during a titration?

pH equals pKa.

What indicates a successful titration endpoint when using bromothymol blue?

The solution should turn green as the pH approaches 7.

What is galvanic corrosion?

Corrosion caused when two different metals are electrically connected in an electrolyte.

What is meant by stress corrosion?

Corrosion accelerated by internal strain or deformation in metals.

What is the relationship between ligand strength and wavelength of maximum absorbance (λmax)?

Stronger ligands lead to lower λmax, indicating higher energy absorption.

What impact do electrolytes have on corrosion rates?

They facilitate electron flow, increasing corrosion.

How can you determine if a process is spontaneous based on Gibbs free energy changes?

A process is spontaneous if ∆G is negative.

What color indicates the presence of OH− ions in a solution?

The solution turns pink.

What does a higher energy light absorb in terms of crystal field splitting?

Absorption occurs at a lower wavelength.

How do you calculate the standard cell potential for a galvanic cell?

By summing the reduction half reaction and the oxidation half reaction.

What happens if you add hydrochloric acid after the titration endpoint?

The solution will turn yellow, indicating an acidic environment.

What is the effect of temperature on the solubility of Ca(OH)₂ if dissolution is exothermic?

Solubility decreases with increased temperature.

What is the chemical reaction for the corrosion of iron?

2Fe + O2 + 2H2O → 2Fe2+ + 4OH−.

When analyzing a titration curve, why is a Gran plot preferred?

It provides a more precise determination of the equivalence volume.