U1-3 - Acids and Bases

Question 1

What is a pH scale?

Answer 1

A measure of the hydrogen ion concentration in a solution.

Low pH = high concentration

Question 2

Acidic solutions have pH…

Answer 2

less than 7.

Question 3

Alkaline solutions have pH…

Answer 3

more than 7.

Question 4

Neutral solutions have pH…

Answer 4

equal to 7.

Question 5

Soluble metal oxides turn solution pH…

Answer 5

alkaline.

Question 6

Soluble non-metal oxides turn solution pH…

Answer 6

acidic.

Question 7

Insolube oxides turn solution pH…

Answer 7

neutral (no effect).

Question 8

Environmental problems caused by non-metal oxide gases

Answer 8

Acid rain, ocean acidification, greenhouse effect.

Question 9

Base

Answer 9

A substance which can neutralise an acid

Question 10

Acid

Answer 10

Substance which contains hydrogen ions (H⁺)

Question 11

Alkali

Answer 11

Soluble base

Question 12

Neutralisation

Answer 12

A reaction between an acid and a base which produces a salt and water.

Question 13

Metal oxide + Acid → …

Answer 13

Salt + Water

Question 14

Metal hydroxide + Acid → …

Answer 14

Salt + Water

Question 15

Metal carbonate + Acid → …

Answer 15

Salt + Water + Carbon dioxide

Question 16

Sodium chloride is a salt.

Where does the ‘sodium’ part come from?

Answer 16

Parent base

(sodium oxide, hydroxide or carbonate)

Question 17

Sodium chloride is a salt.

Where does the ‘chloride’ part come from?

Answer 17

Parent acid

(hydrochloric acid)

Question 18

Phosphoric acid makes …. salts.

Answer 18

phosphate

Question 19

Sulfuric acid makes …. salts.

Answer 19

sulfate

Question 20

Formula for hydrochloric acid

Answer 20

HCl

Question 21

Formula for sulfuric acid

Answer 21

H₂SO₄

Question 22

Formula for phosphoric acid

Answer 22

H₃PO₄

Question 23

Colour of universal indicator in acid

Answer 23

Red

(red/orange/yellow)

Question 24

Colour of universal indicator in alkalis

Answer 24

Blue/purple

Question 25

Colour of **universal indicator** in **neutral** solutions

Answer 25

**Green**

Question 26

Colour of **phenolphthalein** in **acidic** and **neutral** solutions

Answer 26

**Colourless** | (NOT clear!)

Question 27

Colour of **phenolphthalein** in **alkaline** solutions

Answer 27

**Pink**

Question 28

**Ions** which make a solution **acidic**

Answer 28

**H⁺** (hydrogen)

Question 29

**Ions** which make a solution **alkaline**

Answer 29

**OH^–** (hydroxide)

Question 30

Why is water **neutral**?

Answer 30

**Equal** concentrations of **H⁺** and **OH^–** ions.

Question 31

If an **acid** is **diluted**, the pH ...

Answer 31

**increases**.

Question 32

If an **alkali** is **diluted**, the pH ...

Answer 32

**decreases**.

Question 33

If a solution is **diluted**, the **concentrations** of **H⁺** and **OH^–** ions ...

Answer 33

**decrease**.

Question 34

Salt

Answer 34

An ionic compound in which the **H⁺** ions of an acid have been **replaced** by **metal** ions.

Question 35

Spectator ions

Answer 35

Ions which are **unchanged** by a chemical reaction. E.g. Na⁺(aq) → Na⁺(aq)

Question 36

How do we know which ions are **spectator ions** in a reaction?

Answer 36

Ions in the **aqueous product** are spectator ions.

Question 37

A solution of **accurately** known concentration

Answer 37

Standard solution

Question 38

What is the point of **titration**?

Answer 38

To find out an **unknown** concentration by reacting a sample with a **standard solution**.

Question 39

During a titration, what tells you the reaction is **finished**?

Answer 39

The **first permanent** colour change

Question 40

What is a **titre**?

Answer 40

**Volume** of solution added from the **burette** during a titration.

Question 41

What are **concordant titres**?

Answer 41

Titres within **0.2 cm³** of each other.

Question 42

Answer 42

Pipette

Question 43

Answer 43

Burette

Question 44

Titres within **0.2 cm³** of each other are called ....

Answer 44

**concordant**.

Question 45

What is **c₁** and **c₂**?

Answer 45

**Concentrations** of acid and base used in a titration.

Question 46

What is **V₁** and **V₂**?

Answer 46

**Volumes** of acid and base used in a titration. Units must **match**, e.g. both in litres or both in cm³.

Question 47

What is **n₁** and **n₂**?

Answer 47

**Number of moles** of acid and base from the balanced equation.