1.1 formulae and substances

Question 1

molecule

Answer 1

two or more atoms covalently bonded

Question 2

diatomic

Answer 2

two atoms covalently bonded in a molecule

Question 3

ammonium

Answer 3

NH4 +

Question 4

chromium

Answer 4

Cr 3+

Question 5

copper (ii)

Answer 5

Cu 2+

Question 6

iron (ii)

Answer 6

Fe 2+

Question 7

iron (iii)

Answer 7

Fe 3+

Question 8

lead (ii)

Answer 8

Pb 2+

Question 9

silver

Answer 9

Ag +

Question 10

zinc

Answer 10

Zn 2+

Question 11

sulfate

Answer 11

SO4 2-

Question 12

sulfite

Answer 12

SO3 2-

Question 13

thiosulfate

Answer 13

S2O3 2-

Question 14

hydrogen sulfate

Answer 14

HSO4 -

Question 15

Carbonate

Answer 15

CO3 2-

Question 16

hydrogen carbonate

Answer 16

HCO3 -

Question 17

nitrate

Answer 17

NO3 -

Question 18

nitrite

Answer 18

NO2 -

Question 19

phosphate

Answer 19

PO4 3-

Question 20

chlorate

Answer 20

ClO3 -

Question 21

hypochlorite

Answer 21

ClO -

Question 22

hydroxide

Answer 22

OH-

Question 23

dichromate

Answer 23

C2O7 2-

Question 24

Chromate

Answer 24

CrO4 2-

Question 25

permanganate

Answer 25

MnO4 -

Question 26

ionic equation for neutralisation

Answer 26

HCl(aq) + NaOH(aq) ->NaCl(aq) + H2O(l)
H+(aq) + Cl-(aq) + Na+(aq) + OH-(aq) ->Na+(aq) + Cl-
(aq) + H2O(l)
The ionic equation for neutralisation is:
H+(aq) + OH-(aq) ->H2O(l)
Therefore, when any acid reacts with any alkali the ionic equation is the sam

Question 27

ionic equation for precipitation

Answer 27

When two solutions of ionic compounds are mixed, a solid precipitate often forms

BaCl2(aq) + ZnSO4(aq) ->BaSO4(s) + ZnCl2(aq)
Ba2+(aq) + 2Cl-(aq) + Zn2+(aq) + SO42-
(aq) ->BaSO4(s) + Zn2+(aq) + 2Cl-(aq)
Ba2+(aq) + SO42-aq) ->BaSO4(s)

Question 28

sodium hydroxide solution to test for various metal
ions.

Answer 28

When a solution of sodium hydroxide is added to a solution of copper(II)
sulfate, a blue precipitate of copper(II) hydroxide forms. The sodium ions and
sulfate ions are spectator ions. The ionic equation for this reaction is:

Cu2+(aq) + 2OH-
(aq)  Cu(OH)2(s)

Question 29

ionic equation for displacement

Answer 29

A displacement reaction occurs when a more reactive metal displaces a less reactive
metal from a metal compound. For example, when magnesium reacts with
copper(II) sulfate, the magnesium atoms react with the copper ions in the copper(II)
sulfate. The sulfate ions are spectator ions and do not appear in the ionic equation.

Question 30

avogadro constant

Answer 30

number of carbon atoms in 12.000g of carbon-12

Question 31

mole

Answer 31

the amount of substance which contains the avogadro constant of atoms, molecules and groups of ions

Question 32

molar mass

Answer 32

the mass of one mole of a substance

Question 33

anhydrous

Answer 33

a sakt which contains no water of crystallisation

Question 34

hydrated

Answer 34

a salt which contains water of crystallisation

Question 35

water of crystallisation

Answer 35

water chemically bonded within a crystal structure

Question 36

Experimental determination of the mass of water of crystallisation in hydrated crystals

Answer 36

Water of crystallisation can be removed by heating to constant mass. The anhydrous salt is
formed (this is often referred to as the residue). This can be represented in an equation. For
example, for hydrated copper(II) sulfate, the equation is:
hydrated copper(II) sulfate → anhydrous copper(II) sulfate + water
CuSO4.5H2O → CuSO4 + 5H2O
Method=
To heat to constant mass:
• weigh the solid and container.
• heat for a few minutes, cool then weigh.
• repeat step 2 until the mass does not change.

Question 37

why do you heat to a constant mass?

Answer 37

To ensure the thermal decomposition is complete and ALL water of crystallisation has been removed.

Question 38

observations when a hydrated solid is heat

Answer 38

• crystalline solid changes to powdery solid.
• steam may be given off, or beads of colourless liquid (water) may be observed on the
side of the apparatus.
• there may be a colour change, for example, blue hydrated copper(II) sulfate changes to
white anhydrous copper(II) sulfate.

Question 39

avogadro calculation

Answer 39

No. of particles= No. of moles x Na

Question 40

avogadro constant equation

Answer 40

mass/ RFM = no. particles/Na