Titrations

Which pieces of glassware should be used when preparing a primary standard solution?

• pipette, burette, and conical flask

• dropper, watch glass, and pipette

• beaker, filter funnel, and volumetric flask

• measuring cylinder, stirring rod, and conical flask

A 25.0 mL sample of a 0.100 mol/L hydrochloric acid solution completely reacted with 23.4 mL of sodium hydroxide solution.

What volume of the same sodium hydroxide solution would be required to completely react with 25.0 mL of a 0.100 mol/L acetic acid solution?

• less than 23.4 mL

• 23.4 mL

• more than 23.4 mL

• unable to calculate unless the concentration of the sodium hydroxide solution is also known

Which statement best describes the equivalence point in a titration between a strong acid and a strong base?

• the point at which the first sign of a colour change occurs

• the point at which equal moles of acid and base have been added together

• the point at which the rate of the forward reaction equals the rate of the reverse reaction

A student wishes to determine the concentration of a weak acid by titration with a base of known concentration.

What is the most important property of the base?

• it should be weak

• it should be strong

• it should be a primary standard

• it should not react with carbon dioxide

In a titration of a strong base with a strong acid, the following procedure was used:

1. A burette was rinsed with water and then filled with the standard acid.

2. A pipette was rinsed with some base solution.

3. A conical flask was rinsed with some base solution.

4. A pipette was used to transfer a measured volume of base solution into the conical flask.

5. Indicator was added to the base sample and it was titrated to the endpoint with the acid.

Which statement is correct?

• the calculated base concentration will be correct

• the calculated base concentration will be too low

• the calculated base concentration will be too high

• no definite conclusion can be reached about the base concentration

Citric acid, the predominant acid in lemon juice, is a triprotic acid. A student titrated 25.0 mL samples of lemon juice with 0.550 M NaOH. The mean titration volume was 29.50 mL. The molar mass of citric acid is 192.12 g.

What was the concentration of citric acid in the lemon juice?

• 1.04 g/L

• 41.6 g/L

• 125 g/L

• 374 g/L

A household cleaning agent contains a weak base with the formula NaX. 1.00 g of this compound was dissolved in water to give 100.0 mL of solution. A 20.0 mL sample of the solution was titrated with 0.100 M hydrochloric acid, and required 24.4 mL of the acid for neutralisation.

What is the molar mass of the weak base?

• 82.0 g

• 84.0 g

• 122 g

• 410 g