2.1.4, 2.1.5

Question 1

What is an acid?

Answer 1

A substance that releases hydrogen ions when dissolved in water / proton donor.

Question 2

What is the difference between a strong acid and a weak acid?

Answer 2

Strong acids completely dissociate in water, weak acids partially dissociate.

Question 3

What is an example of a strong acid?

Answer 3

HCl

Question 4

What is an example of a weak acid?

Answer 4

CH3COOH

Question 5

What is a base?

Answer 5

A substance that neutralises an acid to form a salt.

Question 6

What are the 4 bases?

Answer 6

Metal oxides, metal hydroxides, metal carbonates, ammonia

Question 7

What is an alkali?

Answer 7

A base that dissolves in water, releasing hydroxide ions.

Question 8

What is the general formula for neutralisation with metal oxides?

Answer 8

Acid + metal oxide –> salt + water

Question 9

What is the general formula for neutralisation with metal hydroxides?

Answer 9

Acid + metal hydroxide –> salt + water

Question 10

What is the general formula for neutralisation with alkalis?

Answer 10

Acid + alkali –> salt + water

Question 11

What is the general formula for neutralisation with carbonates?

Answer 11

Acid + metal carbonate –> salt + water + carbon dioxide

Question 12

What is a titration?

Answer 12

A technique used to accurately measure the volume of one solution that reacts exactly with another solution.

Question 13

What 3 things can titrations be used for?

Answer 13

• Finding concentration
• Identifying unknown chemicals
• Finding the purity of a substance.

Question 14

What is the method for preparing a standard solution?

Answer 14

1. Weigh solid in a weighing boat using a 2dp balance.
2. Use small amount of distilled water to dissolve solid in a beaker.
3. Transfer solution to a volumetric flask.
4. transfer washings to volumetric flask
5. Add distilled water with pipette to volumetric flask until bottom of meniscus touches line.
6. Add stopper and invert several times.
   6.

Question 15

What is the method for acid-base titrations?

Answer 15

1. Add known volume of base to a conical flask using a pipette.
2. Add acid to burette and record initial volume correct to 0.05cm3.
3. Add 3 drops of indicator to conical flask.
4. Run burette solution into conical flask, swirling flask constantly.
5. Close tap when indicator changes colour and record the final burette reading.
6. Calculate the trial titre.
7. Repeat titration, adding dropwise as the end point is approached.
8. Repeat titrations until concordant results are achieved.

Question 16

What is oxidation number?

Answer 16

The number of electrons involved in bonding to a different element.

Question 17

Why is oxidation number useful?

Answer 17

Checks all electrons have been accounted for when writing formulae.

Question 18

What are the 3 definitions of reduction?

Answer 18

1. Loss of oxygen
2. Gain of electrons
3. Decrease in oxidation number

Question 19

What are the 3 definitions of oxidation?

Answer 19

1. Gain of oxygen
2. Loss of electrons
3. Increase in oxidation number