Topic 5 - Separate Chemistry 1

Question 1

Where are the transition metals positioned on the periodic table

Answer 1

The middle

Question 2

Name some physical properties of transition metals

Answer 2

Good conductors of heat and electricity
Hard shiny and malleable
high melting points
high density

Question 3

Name some chemical properties of transition metals

Answer 3

Good catalysts

Colourful compounds

Question 4

Why does iron have the typical properties of a transition metal

Answer 4

• Its shiny and hard and malleable
• good conductor
• good catalyst used in the Haber process
• colourful compounds

Question 5

What is corrosion due to?

Answer 5

Oxidation

Question 6

How does the rusting of iron occur

Answer 6

When in contact with both water and air

Question 7

How can rusting be prevented?

Answer 7

Painting creates a barrier
Oiling
Sacrificial protection- one more reactive metal coated on top
Galvanising- sacrificial protection with zinc
Electroplating

Question 8

Explain how galvanising works

Answer 8

Zinc is more reactive than iron so will lose electrons and corrode instead

Question 9

Examples of galvanised materials

Answer 9

Steel buckets

corrugated iron roofing

Question 10

What is electroplating

Answer 10

Applying a metal coating to an object using electrolysis

• Cathode is the metal you’re electroplating with
• Your electrolyte contains metal ions of of metal youre plating with

Question 11

Examples of electroplating

Answer 11

Jewellery, decor, kitchen items like cutlery

Question 12

Why might things be electroplated

Answer 12

To make them more unreactive so they dont corrode as easily

To make them look more expensive and improve appearance

Question 13

Name a common alloy

Answer 13

Steel is a alloy of iron made by adding carbon

Question 14

What is an alloy

Answer 14

Made by adding another element to a metal (could be either metal or non-metal)
It can be used to be designed for a specific use

Question 15

Why is iron alloyed

Answer 15

Carbon is added to stop layers of iron sliding over each other meaning that the alloy is stronger (steel)

Question 16

Why are alloys often stronger that the metal they contain

Answer 16

Stops the layers sliding over each other as they have different sized atoms

Question 17

What are some uses for aluminium alloys and why

Answer 17

Aluminium- aircraft -
low density
strong

Question 18

What are some uses for gold alloys and why

Answer 18

Jewellery-
pure gold is soft and malleable 24k
if gold is less than 24k it is an alloy

Question 19

What are some uses for copper alloys and why

Answer 19

Bronze- Copper +tin = harder, used in ornaments

Brass- Copper + zinc = more malleable than bronze , used for taps

Question 20

Why is corrosion of iron a redox reaction

Answer 20

the metal loses its electrons so is oxidised and at the same time oxygen gains elctrons so is reduced

Question 21

What is the theoretical yield of a reaction

Answer 21

The mass of product youd make if all reactants were converted into products (calculate with balanced equation)

Question 22

What is the actual yield

Answer 22

amount of product made

Question 23

How do you calculate percentage yield

Answer 23

Actual yield/ theoretical yield

Question 24

What factors mean that the actual yield is lower than the theoretical yield?

Answer 24

incomplete reactions
unwanted reaction - like if oxygen from air reacts
practical losses - when transferring chemicals some might be left behind in old container

Question 25

How do you calculate atom economy

Answer 25

Total Mr of desired products/ total Mr of all products

Question 26

How would you carry out an acid and alkali titration

Answer 26

- using pipette measure set volume of alkali and add to flask and add few drops of indicator such as phenolphtalein -Fill burette with known concentration of acid at eye level -use burette to add acid to alkali solution and keep adding slowly and swirling until neuatralised and should be light pink - use first as rough and carry out 3 more times now you know where to stop - record volume of acid needed to neutralise alkali called the titre. repeat and take mean

Question 27

How do you calculate the number of moles

Answer 27

Concentration X Volume

Question 28

What is Avogadro's constant

Answer 28

6.02 x 10^23

Question 29

Name some common compounds found in Fertlisers

Answer 29

Nitrogen, phosphorus, potassium

Question 30

What is the difference between small (lab) and large scale production of ammonium nitrate

Answer 30

In a lab- using titration with sulfuric acid in burette, ammona in flask Industrial- using the haber process in a large reaction chamber with ammonium gas and sulfuric acid is sprayed

Question 31

How is ammonium nitrate made using ammonia in the Haber process?

Answer 31

Under controlled conditions in a reactor chamber with: - 200 atmospheres of pressure to increase collisions - 450 degrees for max yield and rate of reaction - Iron catalyst to reach equilibrium faster

Question 32

How does changing the conditions of the Haber Process effect the yield? In terms of pressure and temperature

Answer 32

- The higher the pressure, favors the forwards reaction but too high is too expensive so 200 atm - forwards reaction is exothermic which means if the temp is too high the reaction will go the wrong way---but lower temp means lower rate so 450 degrees is a compromise between the two

Question 33

What does the iron catalyst do?

Answer 33

- Helps to speed up the rate of reaction by having a large surface area for reactions to take place on - Therefore equilibrium is reached faster - Doesn't effect the position of equilibrium

Question 34

How does the equilibrium position determine the reaction pathway

Answer 34

If equilibrium position is shifted to the right (forwards) - it makes lots of products and not as many reactants If equilibrium is shifted to the left (backwards) - it makes more reactants from products

Question 35

How can hydrogen and nitrogen be obtained for the Haber Process

Answer 35

Nitrogen - from air - 78% | Hydrogen - from hydrocarbons such as crude oil

Question 36

What is a chemical cell, what does it use

Answer 36

electrical cell supplied with fuel and oxygen and uses energy from reaction to produce electrical energy efficiently

Question 37

Why does a chemical fuel cell eventually stop producing a voltage?

Answer 37

Because one of the reactants has been used up

Question 38

What are the main features of a hydrogen- oxygen fuel cell

Answer 38

Uses a energy from a hydogen and oxygen reaction to make electrical energy without producing any pollutants

Question 39

Pros and cons of a hydrogen oxygen fuel cell

Answer 39

+more efficient +energy generated directly from reaction (no turbines) +less energy lost as heat or friction +no pollutants - takes up more space - Dangerous and explosive - from hydrocarbons from fossil fuels which needs electricity to make (so doesnt end our dependence on fossil fuels)