Which row shows an advantage and a disadvantage for the stated apparatus used in a titration?
| apparatus | advantage | disadvantage | |
|---|---|---|---|
| A | 25 cm3 volumetric pipette | measures volume accurately | can only be used to measure 25 cm3 of solution |
| B | 50 cm3 burette | measures volume accurately | can only be used to measure 50 cm3 of solution |
| C | 100 cm3 beaker | suitable for filling burette | can only be used to fill a 100 cm3 burette |
| D | 250 cm3 conical flask | allows solutions to be mixed without spilling | not suitable for holding volumes less than 250 cm3 |
▶️ Answer/Explanation
Ans: A
Let’s analyze each option:
Option A: Correct. A volumetric pipette measures exact volumes (like 25.00 cm³) very accurately, but can only measure its fixed volume.
Option B: Incorrect. A burette can measure variable volumes accurately, not limited to 50 cm³ (it can measure any volume up to 50 cm³).
Option C: Incorrect. Beakers aren’t accurate measuring devices, and their disadvantage isn’t limited to filling 100 cm³ burettes.
Option D: Incorrect. Conical flasks can hold volumes less than 250 cm³ perfectly well.
Only option A correctly states both an accurate advantage and limitation of the volumetric pipette.
A scientist uses a titration to calculate the concentration of acid in a sample of lemon juice.
A measured volume of aqueous lemon juice and a few drops of an indicator are added to a flask.
The aqueous lemon juice is then titrated against 0.1 mol/dm³ aqueous sodium hydroxide.
Which piece of apparatus is used to add the aqueous sodium hydroxide to the flask?
A) a burette
B) a delivery tube
C) a measuring cylinder
D) a volumetric pipette
▶️ Answer/Explanation
Ans: A
In a titration, the solution of known concentration (in this case sodium hydroxide) is always added from a burette. A burette allows precise measurement of the volume added, which is essential for calculating the unknown concentration. A delivery tube (B) is used in gas collection, not titrations. A measuring cylinder (C) isn’t precise enough for titration work. A volumetric pipette (D) is used to measure a fixed volume of solution (like the lemon juice being analyzed), not for adding the titrant.
Question
Lime is used to treat an industrial waste.
Which change occurs in the treatment?
Answer/Explanation
Ans:
A
Question
Which piece of apparatus is used to measure variable quantities of liquid in a titration?
Answer/Explanation
Ans:C