U4-2 - General Practical Techniques

Question 1

1.

Why is collection over water unsuitable for gases like sulfur dioxide?

Answer 1

Sulfur dioxide is soluble in water

use gas syringe instead

Question 2

Steps for weighing by tare:
1. Tare balance with container
2. ____________________

Answer 2

Steps for weighing by tare:
1. Tare balance with container
2. Add mass needed to container

Question 3

Steps for weighing by tare:
1. ________________
2. Add mass needed to container

Answer 3

Steps for weighing by tare:
1. Tare balance with container
2. Add mass needed to container

Question 4

What is X?

Answer 4

Residue

This is the solid remaining in the filter paper

Question 5

What is Y?

Answer 5

Filtrate

This is the liquid remaining after solid has been separated

Question 6

Would this be acceptable in a diagram if the substance being heated is flammable?

Answer 6

No, because it could also represent e.g. a Bunsen burner.

Show hot water bath or heating mantle instead

Question 7

How can a flammable substance be heated safely?

Answer 7

By using a hot water bath, heating mantle or hotplate

hot water bath is easiest to draw in a diagram

Question 8

Is this a correct condenser setup if the goal is to prevent volatile reactants from escaping?

Answer 8

No, this is set up for separation of liquid mixtures.
Correct set up must have condenser attached vertically.

Question 9

Name the apparatus most suitable for measuring small volumes of liquid

Answer 9

Pipette

volumetric or graduated both OK

Question 10

Steps for weighing by difference:
1. Weigh + record mass of empty container
2. Weigh + record mass of container + solid
3. ______________

Answer 10

Steps for weighing by difference:
1. Weigh + record mass of empty container
2. Weigh + record mass of container + solid
3. Subtract mass of container from mass of container + solid

Question 11

Steps for weighing by difference:
1. ____________
2. Weigh + record mass of container + solid
3. Subtract mass of container from mass of container + solid

Answer 11

Steps for weighing by difference:
1. Weigh + record mass of empty container
2. Weigh + record mass of container + solid
3. Subtract mass of container from mass of container + solid

Question 12

Steps for weighing by difference:
1. Weigh + record mass of empty container
2. ________________
3. Subtract mass of container from mass of container + solid

Answer 12

Steps for weighing by difference:
1. Weigh + record mass of empty container
2. Weigh + record mass of container + solid
3. Subtract mass of container from mass of container + solid