Self assessment
Question 1 of 7
In the titration of hydrochloric acid with sodium carbonate, which of the following statements are true:
A
An indicator is not necessary
B
If equal volumes of both solutions are to be used, then the acid must be twice as concentrated as the carbonate
C
If equal concentrations of both solutions are used, then the end point will occur when about twice the volume of acid has been added.
D
This experiment could be used as an introduction to using a burette and tritration techniques, writing and applying a balanced equation and predicting the reacting quantities.
In preparing a standard solution of sodium carbonate, the solid sodium carbonate was weighed out accurately, dissolved in a small volume of distilled water added to the beaker, then transferred to a 100 cm3 volumetric flask together with the washings from the beaker. It is carefully made up to the mark with more distilled water to make a solution of 0.50 mol dm-3 concentration. What must the reading on the weighing balance have been?
A
5.3 g
B
53.0 g
C
0.53 g
D
10.6 g
When using titration results for calculations, your students should:
A
Only ignore the rough titration result if it differs significantly from the other results.
B
Always ignore the rough titration result and calculate the average of two concordant titres.
C
Take an average of all the titration results.
D
Take an average of all results that are within 1 cm3 of each other.
| Titration | Volume of sulfuric acid (cm3) |
| 1 | 23.8 |
| 2 | 24.7 |
| 3 |
24.9 |
The results of a student's experiment titrating 0.05 mol dm-3 nitric acid with 15 cm3 of lithium hydroxide solution are recorded above. What is the volume of the average titre and the concentration of the lithium hydroxide?
A
Average titre = 24.5 cm3 and lithium hydroxide concentration = 0.82 mol dm-3
B
Average titre = 24.8 cm3 and lithium hydroxide concentration = 0.83 mol dm-3
C
Average titre = 24.8 cm3 and lithium hydroxide concentration = 0.083 mol dm-3
D
Average titre = 24.5 cm3 and lithium hydroxide concentration = 0.08 mol dm-3
A titration experiment was carried out to find the formula of an unknown acid. 42 cm3 of a solution of NaOH (0.1 mol dm-3) neutralised 21 cm3 acid (0.1 mol dm-3). Which of the following could represent the formula of the acid?
A
HA
B
H2A
C
H3A
D
H4A
What might you, the teacher, say if your student was struggling with titration calculations?
A
Just learn the 'magic triangle' of moles, volume and concentration and plug in the numbers.
B
You should do more homework.
C
Let's break down the calculation into small chunks and work through each small step.
D
You should have paid attention to my thorough explanation.
In a titration experiment the alkali is preferable, where possible, in the conical flask and not in the burette. Which reasons might explain this?
A
the burette tap can easily clog if alkali is used and if the water evaporates to leave a solid if the burette is not washed immediately and thoroughly.
B
it is easier to read the burette if it contains the acid.
C
Repeated and prolonged use of alkalis, such as NaOH and KOH, could wear away the glass over time, slightly altering the internal diameter of the burette.
D
it is convention to put the acid in the burette and the alkali in the flask.