Chemistry

Question 1

Chemical reaction

Answer 1

When an old substance dissapears and a new substance forms

Question 2

Old substance

Answer 2

Is known as the reactant

Question 3

New substance

Answer 3

Is known as the product

Question 4

Chemical equation

Answer 4

Reactants -> products for example Oxygen+magnesium -> magnesium oxide

Question 5

Types of reactions

Answer 5

Combustion, Photosynthesis, Respiration, Corrosion and Fermentation

Question 6

Combustion

Answer 6

Any reaction that involves burning with oxygen to release light and heat e.g burning a match

Question 7

Photosynthesis

Answer 7

Is a series of chemical reactions that uses sunlight to convert water and carbon dioxide into oxygen and glucose.

Question 8

Respiration

Answer 8

A chemical reaction that converts oxygen and glucose into carbon dioxide and water vapour, respiration releases water vapour.

Question 9

Corrosion

Answer 9

A chemical reaction that causes metals to react with water and oxygen e.g iron forms rust

Question 10

Fermentation

Answer 10

Is an anaerobic process carried out my microorganisms like yeast and bacteria, is used in food production (bread), wine) and biofuel production (ethanol)

Question 11

Anaerobic

Answer 11

Without oxygen

Question 12

Aerobic

Answer 12

With oxygen

Question 13

Aq/aqueous

Answer 13

Dissolved in water

Question 14

Molecular compound

Answer 14

All the molecules in a compound are identical in size and shape, and have the same number of atoms. Scientists represent the molecules of a compound using a molecular formula, it describes how many of each atom make up the molecule

Question 15

Photosynthesis Chemical equation

Answer 15

Carbon dioxide+ water -> Oxygen+ glucose

Question 16

Respiration Chemical equation

Answer 16

Glucose+Oxygen -> Carbon dioxide+Water vapour+ energy

Question 17

Corrosion Chemical equation

Answer 17

Iron+water+oxygen-> iron oxide

Question 18

Complete combustion

Answer 18

When there is plenty of oxygen

Question 19

Equation example of complete combustion

Answer 19

Hydrocarbon (CH) + Oxygen (O2) -> Carbon Dioxide (CO2) + Water (H2O) + Soot (Carbon)

Question 20

Incomplete combustion

Answer 20

Where oxygen is limited

Question 21

Incomplete combustion example equation

Answer 21

Hydrocarbon + (Not enough oxygen O2) -> Water (H2O)+ Carbon monoxide (CO) + Soot (Carbon)

Question 22

Endothermic Reaction

Answer 22

Reactions that take in energy (heat) e.g photosynthesis (plants making sugar) photosynthesis= CO2 + H2O -> C6H12O6 (Glucose) + O2

Question 23

Combustion of Methane

Answer 23

Methane is the primary component of natural gas, which is used for heating homes and generating electricity

Question 24

Methane Combustion Word Equation

Answer 24

Methane + Oxygen -> Carbon Dioxide + Water

Question 25

Methane Combustion Symbol Equation

Answer 25

CH4+ 2O2 -> CO2 + 2H2O

Question 26

Combustion of Ethanol

Answer 26

Ethanol is commonly used as a biofuel additive in gasoline to reduce greenhouse gas emmissions

Question 27

Ethanol Combustion Word Equation

Answer 27

Ethanol + Oxygen -> Carbon Dioxide + Water

Question 28

Ethanol Combustion Symbol Equation

Answer 28

C2H5OH + 3O2 -> 2CO2+ 4H2O

Question 29

Combustion of Propane

Answer 29

Propane is used as a clean-burning fuel for residential and commercial heating, cooking and powering appliances like stove and grills

Question 30

Propane Combustion Word Equation

Answer 30

Propane + Oxygen ->Carbon dioxide+ Water

Question 31

Propane Combustion Symbol Equation

Answer 31

C3H8 + 5O2 -> 3CO2 +4H2O

Question 32

Combustion of Hydrazine

Answer 32

Hydrazine is commonly used as a rocket propellant due to its high energy content

Question 33

Hydrazine Combustion Word Equation

Answer 33

Hydrazine + Oxygen -> Nitrogen gas + Water

Question 34

Hydrazine Combustion Symbol Equation

Answer 34

N2H4 + O2 -> N2 + 2H2O

Question 35

5 signs a Chemical reaction has occurred

Answer 35

Gas being released, colour change, new smell, solid (precipitate) is formed and temperature change

Question 36

Energy change

Answer 36

When a temperature change occurs, this indicate the energy has changed forms. Energy may be needed for the reaction to occur, or it may be produced as a result of the reaction. When a reaction occurs bonds can be broken or formed

Question 37

Endothermic Reaction

Answer 37

Heat is absorbed and the energy increases (absorbed from surroundings)

Question 38

Exothermic Reaction

Answer 38

Heat is released and energy is lost (released to the surroundings)

Question 39

Conservation of Mass law

Answer 39

In a closed system ( nothing goes in the system, nothing leaves the system), the mass of reactants in a chemical reaction must equal the mass of the products after the reaction

Question 40

Why this happens (Law of conservation of mass)

Answer 40

During a chemical reaction atoms are neither created nor destroyed, the atoms of the reactants are just rearranged to from product and there is no change in the mass in a chemical equation

Question 41

Conservation of mass example

Answer 41

Methane (CH4) + Oxygen (O2) -> Carbon dioxide (CO2) + Water (H2O)