Corrections

Question 1

Name 2 industries that use enzymes in its production process

Answer 1

brewing
baking

Question 2

What is a catalyst (3)

Answer 2

• increases rate of reaction
• not used up during the reaction
• lowers activation energy

Question 3

formula for rate of reaction using formation of a product

Answer 3

= amount of product formed (or lost) / time

Question 4

Why does a cross disappear in a reaction (2)

Answer 4

Because solid — is precipitated. The solid blocks view of the cross.

Question 5

name an advantage of a inverted measuring cylinder over a gas syringe

Answer 5

none of the gas escapes before the syringe is connected

Question 6

What is activation energy

Answer 6

Minimum amount of energy required for a reaction to take place

Question 7

How does a larger surface area increase rate of reaction

Answer 7

more particles are able to be involved in collisions

Question 8

How do you find rate of reaction at a specific point in a rate of reaction graph

Answer 8

draw a tangent and find the gradient

Question 9

what happens to rate of reaction over time (2)

Answer 9

the rate decreases over time due to reactant particles being used up so there are fewer reactant particles

Question 10

What is sulfur scrubbing (3)

Answer 10

• exhaust gases containing sulfur dioxide are sprayed with ‘limestone slurry’.
• The sulfur dioxide reacts with the slurry to form calcium sulfate
• which is removed as solid waste

Question 11

benefits of sulfur scrubbing (2)

Answer 11

• reduces sulfur dioxide emissions reducing acid rain
• solid calcium sulfate can be made into plaster boards

Question 12

composition of modern atmosphere (4)

Answer 12

• 78% nitrogen
• 21% oxygen
• 0.9% argon
• 0.04% CO2

Question 13

Where did ammonia from our previous atmosphere go

Answer 13

reacted with oxygen to form nitrogen gas and water.

Question 14

use of nitrogen

Answer 14

unreactive atmospheres for food packaging

Question 15

describe a test for the gas produced when carbonates decompose (2)

Answer 15

• heat in a boiling tube with delivery tube
• bubble gas through limewater and limewater turns milky

Question 16

how are gases separated using fractional distillation (2)

Answer 16

• they have different boiling points
• gases collected at different places on the column in order of boiling points

Question 17

why didn’t scientists believe Alfred Wegener

Answer 17

he was unable to explain how continents moved

Question 18

2 pieces of evidence Alfred Wegener had of continental drift

Answer 18

• similar fossil patterns on different continents
• coastlines of continents fit together like a jigsaw

Question 19

What do all metal oxides look like

Answer 19

white solids

Question 20

ionic formulae for displacement reaction between sodium bromide + chlorine

Answer 20

2Br + Cl2 —- 2Cl + Br2

Question 21

why does mass decrease in a reaction

Answer 21

gas is released

Question 22

why are catalysts important in industrial processes

Answer 22

Reactions can take place at lower temperatures so less energy is needed therefore its cheaper to make the products

Question 23

common name for sodium carbonate

Answer 23

washing soda

Question 24

what does washing soda do

Answer 24

reacts with calcium and magnesium ions to produce insoluble salts

Question 25

What does boiling do

Answer 25

decoposes hydrogencarbonate ions

Question 26

how are oxygen and carbon dioxide levels in the atmosphere maintained

Answer 26

• photosynthesis uses CO2 and releases O2
• respiration uses O2 and releases CO2
• balance is maintained when both oxygen and carbon dioxide are used up at the same rate they are produced

Question 27

safety measure in reaction of potassium with water

Answer 27

Use a small piece of potassium

Question 28

what is a practical problem when trying to get crystals to form at 4 degrees celsius and solution to this

Answer 28

• it is lower than room temperature
• difficult to get crystals to form
• place the boiling tube in ice

Question 29

formula for decomposition of calcium hydrogen carbonate

Answer 29

calcium hydrogencarbonate + water + carbon dioxide

Question 30

what does adding washing soda to hard water form visibly

Answer 30

a white precipitate

Question 31

metal properties given in table with melting point, boiling point, density and conductivity (4)

Answer 31

• high boiling point
• high melting point
• high density
• being a conductor

Question 32

Describe the theory of plate tectonics

Answer 32

• The Earth’s crust is divided into tectonic plates
• these move very slowly
• due to convection currents in the mantle

Question 33

what ions do group 1 elements form when they react

Answer 33

+1

Question 34

what ions do group 7 elements form when they react

Answer 34

-1

Question 35

describe a method of testing for water hardness (4)

Answer 35

• add soap solution to each sample and shake
• the one that produces a lather is soft water
• boil the remaining samples
• the one that lathers after boiling is temporary hard water and the one that does not is permanent hard water

Question 36

empirical formula =

Answer 36

mass\Ar. NOT Mr