CHEMICAL EQUATIONS

Chemical equations  You are expected to know these names and formula: NameFormulaNameFormula WaterH2OH2OHydrchloric Acid HCl Carbon Dioxide CO 2 Sulfuric AcidH 2 SO 4 Sulfur DioxideSO 2 Nitric AcidHNO 3 Sulfur TrioxideSO 3 Ethanoic AcidCH 3 COOH Nitrogen Dioxide NO 2 AmmoniaNH 4

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 + O 2  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 + O 2  MgO  Balanced: 2Mg + O 2  2MgO

Activity 1. Write down how many of each type of atom are present: a) H 2 b) CO 2 c) N 2 d) CH 4 e) SO 2 f) Al 2 O 3 g) C 3 H 8

Activity cont… h) CuSO 4 i) NO j) Fe 2 O 3 k) Cu(OH) 2 l) (NH 4 )2SO 4

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 – Cl 2 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 – Cl 2 means 2 lots of Cl.  Big numbers in front of the compound mean you multiply the elements by it. Eg – 2NH 4 = 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 – Cl 2 means 2 lots of Cl.  Big numbers in front of the compound mean you multiply the elements by it. Eg – 2NH 4 = 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 – Cl 2 means 2 lots of Cl.  Big numbers in front of the compound mean you multiply the elements by it. Eg – 2NH 4 = 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 – (NH 4 ) 3 means 3N, 12H

Answers a) 2 H b) 1 C, 2 O c) 2 N d) 1 C, 4 H e) 1 S, 2 O f) 2 Al, 3 O g) 3 C, 8 H h) 1 Cu, 1 S, 4 O i) 1 N, 1 O j) 2 Fe, 3 O k) 1 Cu, 2 O, 2 H l) 2 N, 8 H, S, 8 O

Activity 2. Write down the total number of atoms present in these: a) 2NO 2 b) 3H 2 O c) 4NH 3 d) S8 e) 2Ca 3 (PO 4 ) 2 f) 2CaCO 3

g) 5C 4 H 10 h) 2CH 3 OH i) 2C 6 H 12 O 6 j) 4MgCl 2 k) 4Na 2 CO 3 l) 2H 2 SO 4

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 + H 2 O  CO + H 2 b) Mg + O 2  MgO c) CH 4 + O 2  CO 2 + H 2 O d) CuO + H 2  Cu + H 2 O e) C 2 H 6 + O 2  CO 2 + H 2 O f) Mg + H 2 O  Mg(OH) 2 + H 2 g) Fe 2 O 3 + CO  Fe + CO 2 h) Fe + Cl 2  FeCl 3

Answers a) C + H 2 O  CO + H 2 b) 2Mg + O 2  2MgO c) CH 4 + 2O 2  CO 2 + 2H 2 O d) CuO + H 2  Cu + H 2 O e) 2C 2 H 6 + 7O 2  4CO 2 + 6H 2 O f) Mg + 2H 2 O  Mg(OH) 2 + H 2 g) Fe 2 O 3 + 3CO  2Fe + 3 CO 2 h) 2Fe + 3Cl 2  2FeCl 3