Useful chemical reactions-review

Basic chemistry

100

Question number 1 on page 107

a. Melting ice - Physical change

b. Baking a cake - Chemical change

c.  Mixing sand and gravel - Physical change

d.  Nail rusting - Chemical change

200

Question 11, p. 107

Iron chloride and hydrogen gas

300

Question 1, p. 106

a     Lead - Metal

b     Sodium nitrate - Salt

c     Potassium hydroxide - Base

d     Sodium carbonate - Carbonate

e     Sulfuric acid - Acid

400

Question 12, p. 107

All combustion reactions use oxygen and produce carbon dioxide, making respiration difficult. When there is not enough oxygen gas for complete combustion, incomplete combustion may occur, producing carbon monoxide.  Carbon monoxide is poisonous and can be fatal

scientific terms

100

Question number 2 on p. 107

Define the following:

a. chemical reaction

b. Salt

a. A chemical reaction is a change in which a new substance is formed

b. A salt is a type of compound formed when an acid and a base react. It usually consists of a metallic and a non-metallic part.

200

Question number 2 on p. 107

Define: 

c. Neutralization 

d. combustion

Neutralisation is a type of chemical reaction that occurs when an acid and a base combine. Both are neutralised.

A combustion reaction is a type of chemical reaction in which a substance (usually a fuel) reacts with oxygen and releases energy in the form of heat and light.

300

Question number 4 on p. 107

Mass is neither created nor destroyed during a chemical reaction. This means that the atoms that were present at the start of the reaction are also present at the end of the reaction. Therefore, in a chemical equation the number of atoms of each element in the reactants must be the same as the products

400

Question 2, p.106

a     acid + base ® salt + water

b     acid + carbonate/bicarbonate/hydrogen carbonate ®salt + carbon dioxide + water

c     acid + metal ® salt + hydrogen gas

chemical reaction

100

Question number 3 on p. 107

change in temperature

 permanent change in colour

production of a solid (precipitate) from liquid reactants

 production of bubbles of a gas

 production of light.

200

Question number 6 on p. 107

A synthesis reaction is the opposite of a decomposition reaction. In a synthesis reaction two or more reactants combine to form a single product. Whereas in a decomposition reaction, a single reactant breaks down into two or more products.

300

Question 8, p. 107

Place a lit splint or taper near the gas. A ‘pop’ sound would indicate whether the gas is hydrogen.

400

Question 10, p.107

a     It is a decomposition reaction.

b     sodium hydrogen carbonate → sodium carbonate + carbon dioxide + water

c     2NaHCO3 → Na2CO3 + CO2 + H2O

Balancing chemical equation

100

Question number 7 on p. 107

Balance equation: Mg + HCl -----} MgCl₂ + H₂

Mg + 2HCl → MgCl₂ + H₂

200

Question 7, p. 107

Balance equation: S₈ + O₂ -----} SO₂

S₈ + 8O₂ → 8SO₂

300

Question 7, p. 107

balance equation: Al + Br₂ -----} AlBr₃

2Al + 3Br₂ → 2AlBr₃

400

Question 9, p.107

a     nitrogen gas + hydrogen gas → ammonia gas

b     N₂ + 3H₂ → 2NH₃

c     It is a synthesis reaction.