Acids, alkalis and salts

Question 1

Acid

Answer 1

proton donor

H+ ions in solution (aq)

Question 2

Alkali

Answer 2

OH - ions
in solution (aq)

(type of base)
common alkalis: ammonia, metal hydroxides

Question 3

Base

Answer 3

proton acceptor
a substance that neutralises an acid (usually forms water)

common bases: metal oxides, metal carbonates

Question 4

Salt

Answer 4

• when H+ ion in an acid
• is replaced by a +ve ion

(Ionic substances formed when acids react with bases)
common salts: sulfates, chlorides, nitrates, phosphates, ethanoates, citrates

Question 5

metal + acid ➝

Answer 5

metal + acid ➝ salt + hydrogen

Question 6

metal oxide + acid ➝

Answer 6

metal oxide + acid ➝ salt + water

Question 7

metal hydroxide + acid ➝

Answer 7

metal hydroxide + acid ➝ salt + water

Question 8

metal carbonate + acid ➝

Answer 8

salt + water + carbon dioxide

Question 9

ammonia + acid ➝

Answer 9

ammonium salt

Question 10

Acidic or basic oxide

Answer 10

Acidic oxides = nonmetal
Basic Oxides = metal

Question 11

Neutral oxides
give 3 examples

Answer 11

do not react with either acids or bases
e.g. NO (nitric oxide) and CO

Question 12

Amphoteric oxides
what is formed?

Answer 12

react with both acids and bases to form salt and water
e.g. zinc oxide and aluminum oxide

Question 13

metal hydroxide + carbon dioxide

Answer 13

metal carbonate + water

Question 14

pH scale

Answer 14

0-6 = acid
7 = neutral
8-14 = alkali

Question 15

Universal Indicator

Answer 15

RED = 0-6 = acid
yellow
GREEN = 7 = neutral
blue
PURPLE = 8-14 = alkali

Question 16

Methyl Orange

Answer 16

RED - acidic solutions
YELLOW = alkaline solutions / neutral

Question 17

Litmus paper

Answer 17

comes in 2 forms - red & blue
red ➝ BLUE = alkaline solutions
blue ➝ RED - acidic solutions

Question 18

What is meant by a strong and weak acid/base? What do salts of weak acids/base can affect?

Answer 18

Strong - complete dissociation in an aqueous solution
Weak - partial dissociation into its ions in water

Salts of weak acids or bases can affect the acidity or basicity of their aqueous solutions

Question 19

metal + water

Answer 19

metal + water ➝ metal hydroxide + hydrogen

Question 20

less reactive metals only react with steam
metal + steam

Answer 20

metal + steam ➝ metal oxide + hydrogen

Question 21

4 main steps of preparation of salts

Answer 21

1. neutralisation (metal oxide + acid, + base)
2. filtration
3. evaporation
4. crystallisation

Question 22

What is meant by the term saturated solution

Answer 22

M1 containing the maximum amount of dissolved solute / no more solute can dissolve
M2 at any given temperature

Question 23

aluminium oxide is amphoteric. It is insoluble in water. Describe experiments to show that aluminium oxide is amphoteric. [3]

Answer 23

Al2O3 will react/neutralise both reagents
acid (HCl) and alkali (NaOH)
and so it will dissolve into the reagent/form a solution

Question 24

ammonium salt + base

Answer 24

ammonium salt + base ➝ ammonia + salt + water

Question 25

neutralisation reaction used to do what

Answer 25

used to control soil acidity - soil pH, affects plant growth, lime, CaO, often used

Question 26

what is meant by ionise in solution

Answer 26

splitting up to produce hydrogen ion, H+ and another
HCl -> H+ + Cl-

Question 27

strength and concentration difference

Answer 27

strength - what proportion of molecules ionise in water
concentration - how much acid/base there is in a volume of water