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CHEMICAL EQUATIONS
Chemical equations
You are expected to know these names and formula:
Name Formula Name Formula
Water H2O Hydrchloric Acid
HCl
Carbon Dioxide
CO2 Sulfuric Acid
H2SO4
Sulfur Dioxide
SO2 Nitric Acid HNO3
Sulfur Trioxide
SO3 Ethanoic Acid
CH3COOH
Nitrogen Dioxide
NO2 Ammonia NH4
Chemical Equations
All are written in this structure:Reactants Products(Starting materials) (what is produced)
Writing chemical equations
1. Identify the reactants and products by looking at information or observing the reaction carefully.
Writing chemical equations
1. Identify the reactants and products by looking at information or observing the reaction carefully.
2. Write a word equation. In word equations, the reactants and products are named.
Writing chemical equations
1. Identify the reactants and products by looking at information or observing the reaction carefully.
2. Write a word equation. In word equations, the reactants and products are named.
3. Decide on the symbols and formulae for the reactants and products and write a chemical equation with these symbols and formulae.
Writing chemical equations
1. Identify the reactants and products by looking at information or observing the reaction carefully.
2. Write a word equation. In word equations, the reactants and products are named.
3. Decide on the symbols and formulae for the reactants and products and write a chemical equation with these symbols and formulae.
4. Balance the equation if necessary.
Example
Magnesium and oxygen Word equation:
Example
Magnesium and oxygen Word equation: magnesium + oxygen
magnesium oxide Symbol equation:
Example
Magnesium and oxygen Word equation: magnesium + oxygen
magnesium oxide Symbol equation: Mg + O2 MgO
Example
Magnesium and oxygen Word equation: magnesium + oxygen
magnesium oxide Symbol equation: Mg + O2 MgO Balanced:
Example
Magnesium and oxygen Word equation: magnesium + oxygen
magnesium oxide Symbol equation: Mg + O2 MgO Balanced: 2Mg + O2 2MgO
Activity
1. Write down how many of each type of atom are present:
a) H2
b) CO2
c) N2
d) CH4
e) SO2
f) Al2O3
g) C3H8
Activity cont…
h) CuSO4
i) NOj) Fe2O3
k) Cu(OH)2
l) (NH4)2SO4
Remember!
Capital letters on their own represent elements.
Remember!
Capital letters on their own represent elements. Eg – CHO means 1 Carbon, 1 Hydrogen, & 1 Oxygen.
Remember!
Capital letters on their own represent elements. Eg – CHO means 1 Carbon, 1 Hydrogen, & 1 Oxygen.
Little numbers AFTER the letter mean that the element previous, has that amount. Eg – Cl2 means 2 lots of Cl.
Remember!
Capital letters on their own represent elements. Eg – CHO means 1 Carbon, 1 Hydrogen, & 1 Oxygen.
Little numbers AFTER the letter mean that the element previous, has that amount. Eg – Cl2 means 2 lots of Cl.
Big numbers in front of the compound mean you multiply the elements by it. Eg – 2NH4 = 2 N, 8H
Remember!
Capital letters on their own represent elements. Eg – CHO means 1 Carbon, 1 Hydrogen, & 1 Oxygen.
Little numbers AFTER the letter mean that the element previous, has that amount. Eg – Cl2 means 2 lots of Cl.
Big numbers in front of the compound mean you multiply the elements by it. Eg – 2NH4 = 2 N, 8H
Brackets are used the same way as maths. If there is a little number outside the bracket, you multiply whatever is inside the bracket. Eg -
Remember!
Capital letters on their own represent elements. Eg – CHO means 1 Carbon, 1 Hydrogen, & 1 Oxygen.
Little numbers AFTER the letter mean that the element previous, has that amount. Eg – Cl2 means 2 lots of Cl.
Big numbers in front of the compound mean you multiply the elements by it. Eg – 2NH4 = 2 N, 8H
Brackets are used the same way as maths. If there is a little number outside the bracket, you multiply whatever is inside the bracket. Eg – (NH4)3 means 3N, 12H
Answers
a) 2 Hb) 1 C, 2 Oc) 2 Nd) 1 C, 4 He) 1 S, 2 Of) 2 Al, 3 Og) 3 C, 8 Hh) 1 Cu, 1 S, 4 Oi) 1 N, 1 Oj) 2 Fe, 3 Ok) 1 Cu, 2 O, 2 Hl) 2 N, 8 H, S, 8 O
Activity
2. Write down the total number of atoms present in these:a) 2NO2
b) 3H2O
c) 4NH3
d) S8e) 2Ca3(PO4)2
f) 2CaCO3
g) 5C4H10
h) 2CH3OH
i) 2C6H12O6
j) 4MgCl2k) 4Na2CO3
l) 2H2SO4
Answers
a) 6 (2N, 4O)b) 9 (6H, 3O)c) 16 (4N, 12H)d) 8 (8S)e) 26 (6Ca, 4P, 16O)f) 10 (2Ca, 2C, 6O)g) 70 (20C, 50H)h) 12 (2C, 8H, 2O)i) 48 (12C, 24H, 12O)j) 12 (4Mg, 8Cl)k) 24 (8Na, 4C, 12O)l) 14 (4H, 2S, 8O)
Balance these
a) C + H2O CO + H2
b) Mg + O2 MgO
c) CH4 + O2 CO2 + H2O
d) CuO + H2 Cu + H2O
e) C2H6 + O2 CO2 + H2O
f) Mg + H2O Mg(OH)2 + H2
g) Fe2O3 + CO Fe + CO2
h) Fe + Cl2 FeCl3
Answers
a) C + H2O CO + H2
b) 2Mg + O2 2MgO
c) CH4 + 2O2 CO2 + 2H2O
d) CuO + H2 Cu + H2O
e) 2C2H6 + 7O2 4CO2 + 6H2O
f) Mg + 2H2O Mg(OH)2 + H2
g) Fe2O3 + 3CO 2Fe + 3 CO2
h) 2Fe + 3Cl2 2FeCl3
