Chemistry

Question 1

Test for calcium (Ca2+)

Answer 1

sodium hydroxide: white ppt, insoluble in excess
ammonia: no ppt

Question 2

Test for copper(II) (Cu2+)

Answer 2

sodium hydroxide: light blue ppt insoluble in excess
ammonia: light blue ppt, soluble in excess, forming a dark blue solution

Question 3

Test for Zinc (Zn2+)

Answer 3

Both: white ppt, soluble in excess, forming a colorless solution

Question 4

Test for Ammonia gas (NH3)

Answer 4

damp red litmus paper turns blue)

Question 5

Test for Carbon Dioxide (CO2)

Answer 5

Bubble gas into limewater, white ppt formed. ppt dissolves in excess CO2

Question 6

Test for Chlorine (Cl2)

Answer 6

Bleaches damp litmus paper

Question 7

Test for Hydrogen (H2)

Answer 7

Extinguishes lighted splint with a ‘pop’ sound

Question 8

Test for Oxygen (O2)

Answer 8

Relights a glowing splint

Question 9

Test for Carbonate (CO3,2-)

Answer 9

add dilute acid, effervesence and carbon dioxide produced

Question 10

Test for Chloride (Cl-)

Answer 10

add dilute nitric acid and aq silver nitrate: white ppt

Question 11

Test for Nitrate (NO3-)

Answer 11

add aq sodium hydroxide, aluminum foil and warm. Ammonia produced

Question 12

Test for Sulfate (SO4, 2-)

Answer 12

add dilute nitric acid and aq barium nitrate. White ppt formed

Question 13

Test for Aluminum (Al3+)

Answer 13

sodium hydroxide: white ppt, soluble in excess giving it a colorless solution
aq ammonia: white ppt, insoluble in excess

Question 14

Test for Ammonium (NH4+)

Answer 14

sodium hydroxide: ammonia produced on warming

Question 15

3 Examples of Acids

Answer 15

1. Hydrochloric acid (HCl)
2. Nitric acid (HNO3)
3. Sulfuric acid (H2SO4)

Question 16

dm^3 = cm^3

Answer 16

1dm^3 = 1000cm^3

Question 17

volume of gas (dm^3)

Answer 17

number of moles x 24dm^3

Question 18

find mol using volume and concentration

Answer 18

volume x concentration = mol

Question 19

find mol using mass

Answer 19

mass (given) / Mr (periodic table)

Question 20

examples of alkali

Answer 20

hydroxides or ammonia

Question 21

physical properties of acids (4x)

Answer 21

1. sour taste
2. conducts electricity when dissolved in water to form a solution
3. Ph<7
4. blue litmus paper turns red

Question 22

acid reactions (3x)

Answer 22

1. acid + metal => salt + hydrogen
2. acid + carbonate => salt + carbon dioxide + water
3. acid + alkali (base) => salt and water neutralization

Question 23

properties of alkali (4x)

Answer 23

1. bitter taste
2. slippery and soapy
3. red litmus paper turns blue
4. dissolve in water to form solution that conducts electricity

Question 24

alkali reactions (2x)

Answer 24

1. alkali + acid = salt + water neutralization
2. alkali + ammonium salt (NH4+) = salt + ammonia + water