Chemistry Flashcards

Which of the following describes Le Chatelier's principle?

Answer: A system at equilibrium will shift to counteract any imposed change in conditions

Le Chatelier's principle states that a system in equilibrium will respond to stress (changes in concentration, pressure, or temperature) by shifting to partially counteract the disturbance.

In organic chemistry, which functional group is present in amines?

Answer: –NH₂ (amino)

Amines contain a nitrogen atom bonded to hydrogen and/or carbon atoms; primary amines have the –NH₂ functional group.

Which of the following best describes what happens during saponification?

Answer: An ester reacts with a strong base to form a carboxylate salt and an alcohol

Saponification is the base-catalyzed hydrolysis of an ester, producing a carboxylate salt and alcohol; it is the chemical basis of soap-making from triglycerides.

Which of the following molecules is most likely to exhibit resonance?

Answer: C₆H₆ (benzene)

Benzene exhibits resonance because its delocalized π electrons can be represented by multiple equivalent Lewis structures with alternating single and double bonds.

A solution contains 0.1 mol/L of a weak acid with Ka = 1×10⁻⁵. What is the approximate pH?

Answer: 3.0

For a weak acid, [H⁺] ≈ √(Ka × C) = √(1×10⁻⁵ × 0.1) = √(1×10⁻⁶) = 1×10⁻³, so pH = 3.

Which of the following is an example of a nucleophile in organic chemistry?

Answer: H₂O

Water (H₂O) is a nucleophile because it has lone pairs of electrons on oxygen that it can donate to electrophilic carbon atoms.

What is the relationship between cell potential (E°cell) and the Gibbs free energy change (ΔG°)?

Answer: ΔG° = -nFE°cell

The relationship is ΔG° = -nFE°cell, where n is moles of electrons transferred and F is Faraday's constant; a positive E°cell gives a negative (favorable) ΔG°.