Chemistry (Formulae and Chemical Equations)

Question 1

3 Types of Bonding in Compounds

Answer 1

1) Ionic
2) Covalent
3) Metallic

Question 2

Ionic Bonding

Answer 2

Metal + Non-metal

Question 3

Covalent Bonding

Answer 3

Non-metal + Non-metal

Question 4

Metallic Bonding

Answer 4

Metal + Metal

Question 5

Types of particles involved
Ionic VS Covalent

Answer 5

I - Positive and negative ions which attract each other
C - Molecules formed when atoms share electrons

Question 6

Describe the particles involved
Ionic VS Covalent

Answer 6

I - Metals lose electrons to form positive ions. Non-metals gain electrons to form negative ions.
C - Atoms share electrons to form covalent bonds. A molecule is a collection of atoms held together by covalent bonds.

Question 7

Symbols VS Formulae

Answer 7

Symbols are used to represent elements (E.g. Fl, C, O, etc.)
Formulae are used to represent compounds (E.g. NaCl, KOH, CH4, etc.)

Question 8

Naming Ionic Compounds

Answer 8

1) Name the metal first - the name of the metal never changes
2) The non-metal(s) make up the second half of the name

Question 9

-IDE

Answer 9

1) Compounds containing two elements (E.g. sodium oxide - Na20, zinc sulphide - ZnS, calcium nitride - Ca3N2)
2) Compounds containing a hydroxide ion (E.g. sodium hydroxide - NaOH)

Question 10

-ATE

Answer 10

Compounds containing more than two elements, one of which is OXYGEN
(E.g. potassium nitrate - KNO3, calcium carbonate - CaCO3)

Question 11

State Symbols

Answer 11

S - Solid
L - Liquid
G - Gas
AQ - Aqueous

Question 12

State Symbols in Elements

Answer 12

All uncombined elements are SOLID except:

Hydrogen, nitrogen, oxygen, fluorine, chlorine, the noble gases (helium, neon, argon, krypton, xenon, radon) are all GASes

Mercury and bromine are LIQUIDs

Question 13

State Symbols in Ionic Compounds

Answer 13

Either SOLID or AQUEOUS
(If in doubt, guess aq)

Question 14

State Symbols in Covalent Compounds

Answer 14

Mostly GASes or LIQUIDs

Water (H2O) = LIQUID
Carbon dioxide (CO2), carbon monoxide (CO), sulphur dioxide (SO2), ammonia (NH3), methane (CH4)= all GASES

Question 15

State Symbols in Acids

Answer 15

All AQUEOUS solutions

Question 16

RMM

Answer 16

Relative Molecular Mass (Covalent)

Question 17

RFM

Answer 17

Relative Formula Mass (Ionic)

Question 18

How to calculate RFM

Answer 18

Adding together the relative atomic masses of the atoms in the formula

E.g. 1) Mr(CO2) = 12 + (12 x 6) = 44
2) Mr(Ca(NO3)2) = 40 + (2 x 14) + 96 x 16) = 164
3) Mr(MgSO4.7H20) = 24 + 32 + (16 x 4) + (14 x 1) + (7x 16) = 246

Question 19

How to calculate % by mass of an element in a compound

Answer 19

% by mass of x = (number of atoms of x * Ar / Mr of compound) * 100

E.g. % by mass of Fe = 2 x 56/160 x 100 = 70%

Question 20

Atom Economy
(Definition)

Answer 20

A way of measuring the amount of waste a reaction produces.
A reaction with a HIGH % ATOM ECONOMY will produce LITTLE WASTE whereas one with a low % atom economy will produce a lot of waste and only a small % of the reacting chemicals are converted into useful products.

Question 21

How to calculate % Atom Economy

Answer 21

% atom economy = mass desired product / total mass of reactants x 100

Question 22

When will the atom economy always be 100%?

Answer 22

When there is only one product in the reaction

Question 23

How could the atom economy be made 100%?

Answer 23

By using all the products - you could sell waste products to make a profit

Question 24

Calculate the Atom Economy for 2 methods for extracting copper:
1) Heating copper oxide with carbon (2CuO + C - 2Cu + CO2)
2) Heating copper sulphide with oxygen (CuS = O2 - Cu + SO2)

Answer 24

1) RMM reactants = 2 x CuO
2 X (63.5 X 16) = 159
1 x C = 1 x 12 = 171
RMM useful products = 63.5 x 2 = 127
127/171 x 100 = 74%

2) RMM reactants = Cu + S = 63.5 + 32 + (16 x 2) = 127.5
RMM useful products = 63.5
63.5/127.5 x 100 = 50%