reactions

Question 1

what is a catalyst

Answer 1

Catalysts

Substances that speed up chemical reactions but are unchanged at the end.

Question 2

whats and exothermic reaction

Answer 2

Exothermic
Reactions
One in which energy is given out, usually as heat or light.

Question 3

what is an endothermic reaction

Answer 3

Endothermic
Reactions
One in which energy is taken in, usually as heat.

Question 4

what is a chemical bond

Answer 4

Chemical bond

Force that holds atoms together in molecules.

Question 5

what is a reversible reaction

Answer 5

Reversible
reactions
Reactions where the products can react to remake the original reactants.

Question 6

what are qualities of and exothermic reaction

Answer 6

Exothermic Reactions
Transfer energy to the surroundings
Energy is usually transferred as heat energy
The temperature increase can be
detected using a thermometer
Some examples of exothermic reactions are:
• Burning
• Neutralisation reactions between acids and alkali
• The reaction between water and calcium oxide

Question 7

what are some qualities of endothermic reactions

Answer 7

Endothermic Reactions
Take in energy from the surroundings
The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to get colder.
The temperature decrease can also be detected using a thermometer.
Some examples of endothermic reactions are:
electrolysis
the reaction between ethanoic acid and sodium carbonate
the thermal decomposition of calcium carbonate in a blast furnace

Question 8

what is the law of conservation of mass

Answer 8

Law of Conservation of Mass
“The total mass of the reactants is the same as the total mass of the products.” No atoms are created or destroyed in a chemical reaction. This means that we can say that mass is conserved in a chemical reaction.

Question 9

what is a catalyst

Answer 9

A catalyst is a substance that:
•speeds up reactions
•is not used up during the reaction (its
mass is the same at the start and end of
the reaction)
•is chemically unchanged after the reaction
has finished
Only a very small amount of catalyst is
needed to increase the rate of the reaction
between large amounts of reactants.
Different catalysts are needed to catalyse
different reactions.

Question 10

what are some types of reactions

Answer 10

Combustion
A rapid reaction of a substance with oxygen

Thermal Decomposition
When heating a substance causes it to chemically break down in to two products

Fuel
A material that is burnt to transfer energy in a useful way

Oxidation
A chemical in which substances react with oxygen to form oxides