Topics 4, 5 And 6

Question 1

Name two additional properties shared by transition metals

Answer 1

• high melting points

- form colourful compounds

Question 2

Describe how the structure of a metal allows it to conduct electricity

Answer 2

Electrons move freely through the structure

Question 3

Is the following statement true or false? “Alkali metals have high melting points”

Answer 3

False

They have low melting points because they are soft (can be cut with a knife)

Question 4

Potassium is a group 1 element. When placed in water, a lump of potassium violently explodes A) name the gas that is produced B) describe how the PH of the water changes C) the experiment is repeated with sodium how would it be different?

Answer 4

A) hydrogen gas
B) alkaline (purple water)
C) sodium would fizz rapidly and move quick around the surface and MAY ignite

Question 5

What is the physical state of bromine at room temperature?

Answer 5

Dense
Poisonous
Orange liquid

Question 6

Do hydrogen halides dissolve in water to form acidic or alkaline solutions?

Answer 6

Acidic solutions

Question 7

What is the physical state of chlorine at room temperature?

Answer 7

Reactive
Poisonous
Dense green gas

Question 8

What is the physical state of iodine at room temperature?

Answer 8

Dark grey crystalline solid

Question 9

What is a displacement reaction?

Answer 9

When a more reactive halogen reacts with a solution containing halide ions it pushes out (displaces) the less reactive halogen
Displacement reaction

Question 10

Name a halogen that would displace chlorine from a solution of a chloride

Answer 10

Potassium iodide

Question 11

Explain why the noble gasses are inert (don’t react)

Answer 11

They have a full outer shell so they don’t need to give up or gain electrons

Question 12

Name two noble gasses and state a use for each

Answer 12

Argon - filament lamps (non flammable)

Helium - airships and balloons (lower density than air so floats)

Question 13

What is an exoteric reaction? Give two examples

Answer 13

Gives out energy to the surroundings in the form of heat shown by a rise in temperature e.g burning fossil fuels and explosions

Question 14

What is an endothermic reaction? Give two examples

Answer 14

Takes in energy from the surroundings in the form of heat, show by a fall in temperature
E.g. Photosynthesis and As ammonium nitrate dissolves in water

Question 15

How would you measure the temperature change during a neutralisation reaction?

Answer 15

By mixing the same amount of the reactants at the same temperature in a polystyrene cup
And measure the temperature at the end of the reaction

Question 16

What are the four factors that affect the rate of a reaction

Answer 16

Temperature
Concentration (or pressure for gasses)
Catalyst
Surface are of a solid (or size of particles

Question 17

What is the definition of a catalyst

Answer 17

A substance that speeds up a reaction but isn’t used up or changed

Question 18

What is the role of a catalytic converter in a car exhaust?

Answer 18

To increase the rate at which carbon monoxide and unburnt fuel in the exhaust react with oxygen in the air to produce carbon dioxide and water

Question 19

Excluding catalysts, explain how each of the three other factors which affect reaction rates increase the frequency of collisions between particles.

Answer 19

1) temperature: particles move quicker more frequent collisions
2) concentration or pressure: more particles of reactant between water molecules. More likely to collide. In a gas increased pressure means particles are more squashed up - more frequent collisions
3) larger surface area: larger surface to react with - more frequent collisions

Question 20

What is A(r)

Answer 20

Relative atomic mass

The bigger number on an element in the periodic table

Question 21

What is M(r)

Answer 21

Relative formula mass

The relative atomic mass added up

Question 22

What is the formula for percentage yield?

Answer 22

Percentage yield = actual yield (grams) divided by theoretical yield (grams) times 100

Question 23

Outline two factors that may prevent the percentage yield being 100%

Answer 23

Incomplete reactions
Practical losses during preparation
Unwanted reactions

Question 24

Why may a chemical company wish to avoid using a reaction that produces harmful products?

Answer 24

Pose a threat to people and the environment

Disposing of harmful waste safely is very expensive

Question 25

Give two typical properties of metals

Answer 25

• bendy

- good conductors of heat n electricity

Question 26

How do you work out the percentage mass of an element in a compound

Answer 26

Relative atomic mass times number of atoms divided by relative formula mass times 100

Question 27

How do you find the empirical formula from masses

Answer 27

1) list two elements
2) write the mass
3) divide by atomic mass for each
4) multiply by 10
5) then divide by appropriate number to get the ratio