Chemistry

Question 1

Endothermic reaction

Answer 1

A reaction where the energy is greater in the products than in the reactants

Question 2

Exothermic Reaction

Answer 2

A reaction where energy is greater in the reactants than the products

Question 3

Combustion

Answer 3

When an element, compound, or hydrocarbon is burnt in oxygen to produce significant heat and light

Question 4

Neutralisation

Answer 4

A reaction where an acid is neutralised by a base and vice versa to form a salt and water

Question 5

Acid

Answer 5

A compound that release hydrogen ions

Question 6

Bases

Answer 6

A compound producing hydroxide ions

Question 7

Qualities of acids

Answer 7

pH less than 7, they can be highly corrosive

Question 8

Qualities of bases

Answer 8

pH greater than 7, solution referred to as an alkaline

Question 9

Name some very strong and weak acids

Answer 9

Strong: sulphuric acid, hydrochloric acid, nitric acid
Weak: acetic acid, ethanoic acid, lactic acid, citric acid

Question 10

What are caustic bases and what is an example?

Answer 10

Caustic bases are corrosive bases and an example is sodium hydroxide

Question 11

Where do we use mild forms of bases?

Answer 11

Cleaning products, soap, toothpaste

Question 12

What is the pH level of water and what is it defined as?

Answer 12

The pH level is 7 and it is neutral.

Question 13

Precipitation

Answer 13

When two clear solutions mix to form a soluble product and an insoluble solid, labelled as the precipitate

Question 14

Acid - metal

Answer 14

When an acid reacts with a metal to produce a salt and hydrogen gas

Question 15

Name some very reactive metals

Answer 15

Sodium, potassium, calcium

Question 16

Acid - carbonate

Answer 16

When an acid reacts with a carbonate to produce water, carbon dioxide and a salt

Question 17

What are acid-carbonate reactions used for?

Answer 17

Cleaning up spills

Question 18

Respiration

Answer 18

Chemical reaction in all living cells. It involves the combination of glucose with oxygen to produce carbon dioxide and water. The reaction produces energy so the organism can live, move and grow. It is a slow process.

Question 19

Corrosion

Answer 19

Metals combining with oxygen gas will form metal oxides. This includes the rusting of iron and steel.

Question 20

Difference between corrosion and combustion

Answer 20

Corrosion occurs more slowly in comparison with combustion and doesn’t produce significant amounts of heat and light.

Question 21

What is the rate of reaction?

Answer 21

The speed at which a chemical reaction occurs?

Question 22

How can temperature control the rate of reaction?

Answer 22

Increasing the temperature increases the speed of the particles in liquids and gases so the particles will collide more frequently. The particles also get more energy so when they collide, they hit harder so chemical bonds are likely to break the atoms so they can form their products.

Question 23

How can the concentration control the rate of reaction?

Answer 23

Particles are more likely to collide if concentration is increased and react more often.

Question 24

How can agitation control the rate of reaction?

Answer 24

It ensures reactants are kept in contact by removing the build-up of products around reactants

Question 25

How can surface area control the rate of reaction?

Answer 25

If crushed into small pieces (preferably a powder), more of the reactants are exposed to other reactants so they all react at the same time, hence the reaction is faster

Question 26

How can catalysts control the rate of reaction?

Answer 26

They speed up chemical reactions naturally but are not consumed in the reaction. They reduce the amount of energy required in converting reactants into products and the make it easier for reactants to combine and form molecules.