Chemistry

Question 1

Reactant

Answer 1

Substance(s) that take part in a chemical reaction

Question 2

Product

Answer 2

Substances produced in a chemical reaction

Question 3

Word equation

Answer 3

Shows names of chemicals that are reactants and products

Question 4

Chemical equation

Answer 4

Shows chemical formulas for all reactants and products. Must be balanced on each side, i.e. same amount of H atoms

Question 5

Subscript

Answer 5

Tells us how many atoms there are in the molecule

Question 6

Coefficient

Answer 6

Tells us how many molecules there are

Question 7

Law of conservation of mass

Answer 7

In a chemical reaction, mass (atoms) can’t be created or destroyed, therefore what goes into the reaction must come out, and the mass must be equal.

Question 8

Balancing a chemical equation

Answer 8

Each element must have equal atoms on each side. Can’t change subscripts.

Question 9

Molecules store energy in the form of

Answer 9

Chemical potential energy, so in a chemical reaction energy changes

Question 10

Exothermic reaction

Answer 10

Energy is released, and feels hot. More energy in reactants than products

Question 11

Endothermic reaction

Answer 11

Energy is absorbed, and feels cold. More energy in products than reactants

Question 12

Combustion

Answer 12

Reaction when things burn. Needs oxygen and fuel. Exothermic.

Question 13

Hydrocarbons

Answer 13

Readily undergo combustion. oxygen+ fuel into carbon dioxide + water

Question 14

Incomplete combustion

Answer 14

Not enough oxygen, forms C or CO instead of CO(2) eg. yellow flame on bunsen burner

Question 15

Respiration

Answer 15

combustion in cells of living things, exothermic

Question 16

Oxidation

Answer 16

metal + oxygen into metal oxide

Question 17

Corrosion

Answer 17

When iron undergos oxidation. Produces rust. Needs water. iron + oxygen + water into iron(III) oxide

Question 18

Precipitation reaction

Answer 18

When a soluble compound is mixed with another soluble compound and forms insoluble compound. aq + aq into aq + s
Reactants swap places. Check solubility on table to see if a precipitation reaction occurs.

Question 19

Decomposition reaction

Answer 19

XY into X + Y

Question 20

Thermal decomposition

Answer 20

When heat is needed to decompose a substance

Question 21

Metal oxide decomposition

Answer 21

Some metal oxides decompose to form metals. This was used in Bronze age, when copper oxides were heated to form Bronze.

Question 22

Displacement reaction

Answer 22

When one metal displaces (swaps places) with another metal i.e. AB + C into A + BC. Only happens when C is more reactive than A.

Question 23

(re)activity series

Answer 23

List of metals in decreasing order of reactivity, or decreasing ability to lose outer-shell electrons. Moving up, reactivity is stronger, electrons are less stable, less chance of finding them in their natural state, extraction is harder and more expensive as compounds are stronger

Question 24

collision theory

Answer 24

reactants must collide, sufficient energy, right direction/orientation

Question 25

Factors that change rate of reaction

Answer 25

temperature, concentration, surface area, catalysts

Question 26

Temperature in rate of reaction

Answer 26

atoms move faster, so collide more frequently and with more energy

Question 27

Concentration in rate of reaction

Answer 27

More particles to collide with each other, so collide more

Question 28

Surface area in rate of reaction

Answer 28

More particles open, more particles reacting at the same time

Question 29

Catalyst in rate of reaction

Answer 29

chemicals that speed up rate of reaction but aren’t used up, written above arrow but not in chemical equation. Reduces energy needed for reaction, makes it easier for a successful reaction