Revision

Question 1

Acid +metal carbonate –>
(Na2CO3+2HCl)

Answer 1

Salt+Water+Carbon dioxide
(2NaCl+H2O+CO2)

Question 2

Define relative atomic mass

Answer 2

The weighted mean mass of an atom of an element compared with 1/12th of the mass of an atom of carbon 12

Question 3

Define Mole

Answer 3

The number of atoms in exactly 12 grams of carbon 12

Question 4

Define relative isotopic mass

Answer 4

The mass of an atom of an isotope compared with one twelfth of the mass of an atom of carbon 12

Question 5

Formula triangle of Mr mass moles

Answer 5

M
n|mr

Question 6

Formula triangle of concentration moles and volume

Answer 6

n
C|V

Question 7

Formula triangle of volume moles 24

Answer 7

V
n|24

Question 8

Percentage error =

Answer 8

= glassware error
——————— ×100
quantity measured

Question 9

Colours of halogens when dissolved in water

Answer 9

Cl2 = pale-green
Br2 = Orange
I2 = brown

Question 10

Colours of halogens when dissolved in organic solvents

Answer 10

Cl2 = pale green
Br2 = Orange
Iodine = Purple

Question 11

What are the colours of silver halide precipitates

Answer 11

AgCl = white
AgBr= cream
AgI = yellow

Question 12

What are AgCl,AgBr,AgI soluble and insoluble in

Answer 12

Silver chloride is soluble in dilute ammonia solution
Silver Bromide is insoluble in dilute ammonia solution but soluble in concentrated ammonia solution
Silver Iodide is insoluble in dilute and and concentrated ammonia solution

Question 13

Define precipitate

Answer 13

An insoluble solid formed when two solutions are mixed together

Question 14

Ionic equation and test for carbonate ions [CO3²‐]

Answer 14

Ionic equation = CO3²-[aq] + 2H+[aq] = H2O[l] + CO2[g]

Test = Add HNO3 to the solution
Positive result = effervescence [due to carbon dioxide being produced] [carbon dioxide could be further tested using lime water which would produce a white precipitate]

Question 15

Ionic equation and test for Sulfate ions [SO4²-]

Answer 15

Ionic equation = Ba²±[aq] + SO4²‐[aq] = BaSO4[s]
Test = Add dilute nitric acid followed by barium nitrate solution to the suspected sulfate solution
Positive result = White precipitate forms insoluble barium sulfate

Question 16

Ionic equation and test for halide ions [ Cl‐ Br- I- ]

Answer 16

Ionic equation = Ag+[aq] + X‐[aq] =
AgX[s]
Test = Add dilute nitric acid,followed by AgNO3[aq]
Positive result = white/cream/yellow precipitate forming [insoluble silver halide]

Question 17

Ionic equation and test for Ammonium ions [NH4+]

Answer 17

Ionic equation = NH4+[aq] + OH‐[aq] = NH3[g] + H2O [l]
Test = Add warm dilute aqueous sodium hydroxide [NaOH]
Positive result= Ammonia gas NH3 is produced,ammonia can be detected with moist pH indicator paper which turns blue

Question 18

Reagent for carbonate test

Answer 18

HNO3

Question 19

Reagent for sulfate test

Answer 19

Ba(NO3)2

Question 20

Reagent for halide test

Answer 20

AgNO3

Question 21

Reagent for Ammonium test

Answer 21

Warm dilute NaOH

Question 22

What happens to the solubility of group 2 metals down a group

Answer 22

Solubility increases, solutions become more alkaline due to higher OH- concentrations

Question 23

Trend of group 2 carbonates thermal decomposition down a group

Answer 23

More difficult to decompose as going down the group

Question 24

Trend of reactivity of group 2 metals down a group

Answer 24

More reactive down group because:
• Atomic radius increases/ more shielding
•nuclear attraction decreases
• less energy needed to remove electrons

Question 25

Why does reactivity decrease down group 7/ oxidising power decrease

Answer 25

▪︎More shells
▪︎greater shielding effect
▪︎weaker nuclear attraction on outer shell electrons
▪︎ nucleus less able to attract and capture another electron