Titration IB Chemistry

A student performs an acid-base titration using a pH meter, but forgets to calibrate it. Which type of error will occur and how will it affect the quality of the measurements?

• Random error and lower precision

• Systematic error and lower accuracy

• Systematic error and lower precision

• Random error and lower accuracy

A student carried out a titration to determine the concentration of an acid and found that his value had good precision but poor accuracy. Which process explains this outcome?

• Consistently overshooting the volume of solution from the burette into the flask.

• Collection of insufficient titration data.

• Reading the meniscus in the burette at a different angle each time.

• Forgetting to rinse the flask after one of the titrations.

What is the best way to minimize the random uncertainty when titrating an acid of unknown strength against a standard solution of sodium hydroxide (ie one of known concentration)?

• First standardize the sodium hydroxide solution against a standard solution of a different acid.

• Use a pH meter rather than an indicator to determine the equivalence point.

• Keep your eye at the same height as the meniscus when reading the burette.

• Repeat the titration several times

A student carries out a titration three times and obtains the following volumes: 3.0±0.1cm³, 3.2±0.1cm³ and 3.2±0.1cm³. What is the average volume?

• 3.1±0.1 cm³

• 3.13±0.1 cm³

• 3.1±0.3 cm³

• 3.13±0.3 cm³

The titration curve shows the change in pH when 0.100 mol dm⁻³ sodium hydroxide solution is added to 25.0 cm³ of a weak acid, HA.

What is the concentration, in mol dm⁻³, of the weak acid?

• 0.040

• 0.080

• 0.100

• 0.125

Hydrochloric acid and sodium carbonate solution react as shown below.

2HCl(aq) + Na₂CO₃(aq) → 2NaCl(aq) + CO₂(g) + H₂O(l)

Which sample of sodium carbonate solution will be neutralized by 20 cm³ of 0.05 mol dm⁻³ hydrochloric acid?

• A

• B

• C

• D

25.00 cm³ of 1.00 mol dm^–3 sulfuric acid is fully neutralized by 50.00 cm³ of 1.00 mol dm^–3 sodium hydroxide.

(a) What is the concentration of sodium sulfate solution produced by the reaction, in mol dm^–3?

• 1.00

• 0.67

• 0.50

• 0.33

The volumes are measured using burettes, with each burette reading having an uncertainty of ±0.05 cm³.

The percentage error in measuring the 25.00 cm³ of the acid is

• ±0.05%

• ±0.10%

• ±0.20%

• ±0.40%

During a titration, when the solution in a pipette is transferred to a conical flask, a small amount of liquid remains in the tip of the pipette. This situation should be dealt with by

• leaving the liquid in the pipette which is calibrated to allow for it.

• slightly over-filling the pipette to compensate for the additional volume.

• carefully blowing the liquid out of the pipette to ensure that it is empty.

• repeating the titration.

20 cm³ of sulfuric acid, concentration 0.25 mol dm⁻³, was neutralized in a titration with barium hydroxide, concentration 0.50 mol dm⁻³. The equation for the reaction is

Ba(OH)₂ +H₂SO₄(aq) --> BaSO₄(aq) + 2H₂O(l)

The volume of barium hydroxide required was

• 10 cm³

• 20 cm³

• 25 cm³

• 40 cm³