Chemical Reactions

Question 1

Chemical reaction

Answer 1

A change that results in the formation of one or more new substances

Question 2

Physical change

Answer 2

One where no new substance is formed eg cutting paper

Question 3

Reactants

Answer 3

Chemicals that react together in a chemical reaction

Question 4

Product

Answer 4

The chemicals that are produced in a chemical reaction

Question 5

An example of chemical reaction: chemical equation

Answer 5

Iron + sulfur = iron sulfide

Fe + S = FeS

Question 6

Law of conservation of mass

Answer 6

When a chemical reaction occurs, the total mass of the reactants is always equal to the total mass of the products

Question 7

Investigate if mass is unchanged when a physical change takes place

Answer 7

Melt ice cubes in a container with a lid and measure mass on an electronic balance
No change

Question 8

Investigate if mass is unchanged when a chemical reaction takes place

Answer 8

Sodium chloride solution in a comical flask

• place a test tube with silver nitrate solution inside carefully, suspended by thread
• rubber hung placed on comical flask
• measure mass
• shake comical flask so that it mixes
• new white cloudy substance formed
• measure mass : no change

Question 9

Rate of reaction

Answer 9

The change in concentration per unit time of any one reactant or product

Question 10

Catalyst

Answer 10

A substance that alters the rate of a chemical reaction by speeding it up or slowing it down but is not used up in the reaction
Eg manganese dioxide

Question 11

5 factors that affect the rate of reaction

Answer 11

Type of reactants (nature of reactants) 
Particle size 
Concentration 
Temperature 
Catalyst

Question 12

Experiment : nature of reactants

Answer 12

Magnesium and hydrochloric acid = hydrogen
Zinc and hydrochloric acid = hydrogen

Comical flask with magnesium and dilute hydrochloric acid , with a rubber bung and a tube leading out to an upside down graduated cylinder standing in a basin of water. Have a stopwatch. Measure volume of hydrogen (the water in the graduated cylinder will go down )
Same for zinc, draw graph
Magnesium is faster than zinc

Question 13

Experiment particle size

Answer 13

Calcium carbonate (marble chips) + hydrochloric acid
Measure mass of graduated cylinder w acid inside, comical flask w marble child inside, and cotton wool to prevent spray escaping
Cotton wool only allows carbon dioxide to escape - we will study the loss in mass
Have a stopwatch , pour the acid in and record the loss in mass as it reacts
Repeat with diff size marble chips

Question 14

Experiment concentration

Answer 14

Same setup as the one for type of reactants , magnesium + diff concentrations of hydrochloric acid = hydrogen
Have a stopwatch

Question 15

Experiment temperature

Answer 15

Same setup as nature of reactants
Magnesium + hydrochloric acid = hydrogen
Different temperatures of hydrochloric acid 20,40,60

Question 16

Experiment catalyst

Answer 16

Same setup as nature of reactants
Dilute Hydrogen peroxide in comical flask , with manganese dioxide (catalyst) . Rubber bung. Measure volume of oxygen at regular time intervals

Question 17

Test for hydrogen gas

Answer 17

Burns with a pop when mixed with air

Question 18

Test for carbon dioxide

Answer 18

Turns limewater milky

Extinguished a lighted splint

Question 19

Test for oxygen

Answer 19

Rekindled a glowing wooden splint

Question 20

Biochemical reaction

Answer 20

A chemical reaction that takes place in living cells , where new substances are formed

Question 21

What are enzymes

Answer 21

Biological catalysts

Question 22

Factors affecting rate of biochemical reaction

Answer 22

Concentration of enzymes and substrate

• temperature
• ph

Question 23

What does liver contain

Answer 23

Enzyme catalase which speeds up rate at which hydrogen peroxide is broken down in our bodies