Chemical equations - Science Revision

Question 1

What are the reactants of a chemical equation?

Answer 1

The substances at the start of a chemical reaction which react with each other .

Question 2

What are the products of a chemical equation?

Answer 2

The substances formed by the chemical reaction.

Question 3

What is the law of conservation of mass?

Answer 3

It states that the total mass of the reactants is the same as the total mass of the products.

Question 4

How do you balance chemical equations?

Answer 4

Ensure there are equal numbers of each type of atom on both sides of the equation.

Question 5

What is a synthesis reaction?

Answer 5

A reaction that combines simpler substances to form a new compound.

Question 6

What is the basic equation for a synthesis reaction?

Answer 6

A + B —> AB

Question 7

What is a decomposition reaction?

Answer 7

A reaction that breaks down a compound into simpler substances.

Question 8

What is the basic equation for a decomoposition reaction?

Answer 8

AB —> A + B

Question 9

What is the basic equation for a neutralisation reaction?

Answer 9

Acid + Base —> water + (metal) salt

Question 10

What are the products of an acid + metal reaction?

Answer 10

Salt + hydrogen

Question 11

What are the products of an acid + metal oxide reaction?

Answer 11

Metal salt + water

Question 12

What are the products of an acid + metal carbonate reaction?

Answer 12

Metal salt + water + carbon dioxide

Question 13

What is a precipitate?

Answer 13

An insoluble solid formed between 2 ionic solutions.

Question 14

What is the solubility rule in reference to precipitation reactions?

Answer 14

If a product is insoluble, it will be precipitated out and be the precipitate.

Question 15

What are the 2 precipitation reactions?

Answer 15

Single displacement reaction and Double displacement reaction.

Question 16

What is a single displacement reaction?

Answer 16

When 1 reactant changes partners during the reaction.

Question 17

What is the basic equation for a single displacement reaction?

Answer 17

AB + C —> AC + B

Question 18

What is a double displacement reaction?

Answer 18

When 2 reactants change partners during a reaction.

Question 19

What is the basic equation for a double displacement reaction?

Answer 19

AB(aq) +CD(aq) —> AD(s) + CB(aq)

Question 20

What is an oxidation reaction?

Answer 20

When an element reacts with oxygen.

Question 21

What are the products of a metal + oxygen reaction?

Answer 21

Metal oxide

Question 22

What is an example of a non-metal and oxygen reaction?

Answer 22

2H(g) + 02(g) —> 2H20(g)

Question 23

What are the combustion reactions of hydrocarbons?

Answer 23

Hydrocarbon + oxygen —> carbon dioxide + water

Hydrocarbon + limited oxygen —> carbon monoxide + water

Question 24

What are examples of hydrocarbons?

Answer 24

Methane, ethane, propane, octane and diesel

Question 25

What is a polymer?

Answer 25

A long chain molecule produced by joining small molecules called monomers together through polymerisation.

Question 26

What are the 3 types of structures of a polymer?

Answer 26

Linear Polymers, Elastomers and Cross Linked polymers.

Question 27

What are linear polymers?

Answer 27

Polymers in the form of long chains.

Question 28

What are elastomers?

Answer 28

Polymers in the form of long chains that are connected every now and then with a small chain of atoms.

Question 29

What are cross linked polymers?

Answer 29

Polymers of giant covalent lattices.

Question 30

What are thermoplastic polymers?

Answer 30

Polymers that soften when heated gently and can be bent into a new shape.

Question 31

What are thermosetting polymers?

Answer 31

Polymers that do not melt or change shape when heated.

Question 32

What is a reaction rate?

Answer 32

How fast or slow a reaction occurs.

Question 33

What is the collision theory?

Answer 33

For chemical reactions to occur, the atoms must collide with enough energy for the reaction to occur.

Question 34

How do you increase the reaction rate?

Answer 34

You need to increase the number of collisions occurring.

Question 35

How does increasing the surface area increase the reaction rate?

Answer 35

Breaking one of the reactants into smaller pieces allows more area for the collisions to occur.

Question 36

How does increasing the concentration increase the reaction rate?

Answer 36

In a concentrated solution - there are more reactant particles.

Question 37

How does increasing the temperature increase the reaction rate?

Answer 37

Particles in a hot temperature have more kinetic energy that causes the particles to collide more and at a faster speed.

Question 38

How does stirring and mixing increase the reaction rate?

Answer 38

It removes the products of the reaction and replaces them with more particles of the reactants.

Question 39

What are the states and symbols in a chemical reaction?

Answer 39

Gas = g Liquid = l Solid = s Aqueous = aq

Question 40

What does aqueous mean?

Answer 40

It dissolves in water

Question 41

What is an independent variable?

Answer 41

The variable that stands alone and isn’t affected by other variables.

Question 42

What is a dependant variable?

Answer 42

The variable being measured or tested - that changes because of the independent variable.