Understanding Weak Acids and pH Calculations

The video tutorial discusses weak acids, focusing on their dissociation, equilibrium, and pH calculation. It explains the difference between strong and weak acids, emphasizing the degree of dissociation. Using acetic acid as an example, the video demonstrates how to set up equilibrium equations and calculate pH using ICE tables and Ka values. It also highlights the inverse relationship between the strength of acids and their conjugate bases, using hydrofluoric acid as another example.

What is the primary difference between strong acids and weak acids?

• Strong acids dissociate completely, while weak acids only partially dissociate.

• Weak acids dissociate completely in water.

• Strong acids have a higher molecular weight.

• Weak acids are more reactive than strong acids.

Which of the following is a characteristic of weak acids?

• They have a pH of 7.

• They are always organic compounds.

• They dissociate about 5% in water.

• They do not form equilibrium in water.

How can you identify a weak acid from its formula?

• It contains a metal ion.

• It is not one of the seven strong acids.

• It has a high boiling point.

• It is a gas at room temperature.

What is the formula for acetic acid?

• NH3

• CH3COOH

• HCl

• H2SO4

What is the purpose of using an ICE table in pH calculations for weak acids?

• To determine the boiling point of the solution.

• To calculate the initial concentration of the acid.

• To track changes in concentrations and establish equilibrium.

• To measure the temperature change during the reaction.

Why can the assumption be made that X in the denominator is negligible in weak acid calculations?

• Because the Ka value is large.

• Because the initial concentration is zero.

• Because the reaction is product-favored.

• Because the change in concentration is minimal.

What is a sign that a substance is a weak acid?

• It has a low Ka value.

• It is a strong electrolyte.

• It has a high Ka value.

• It is a solid at room temperature.

What is the relationship between a weak acid and its conjugate base?

• A weak acid has a weak conjugate base.

• A weak acid has a relatively strong conjugate base.

• A weak acid has no conjugate base.

• A weak acid has a neutral conjugate base.

Which of the following is true about hydrofluoric acid (HF) in water?

• HF does not react with water.

• HF forms a relatively strong conjugate base, fluoride.

• HF dissociates completely in water.

• HF is a strong acid.

What happens when fluoride ions are present in water?

• They act as acids.

• They remain unreactive.

• They act as bases and can form hydrofluoric acid.

• They increase the water's temperature.