Seperate chemistry 1

Question 1

Where are the transition metals located on the periodic table?

Answer 1

In the middle.

Question 2

What are the properties of the transition metals?

Answer 2

• High melting point
• High density
• Typical metal properties

Question 3

Transition metals and their compounds make good what?

Answer 3

Catalysts.

Question 4

What is a catalyst?

Answer 4

It speeds up the rate of reaction without being changed or used up itself.

Question 5

The compounds of transition metals tend to be what?

Answer 5

Very colourful.

Question 6

What are alloys?

Answer 6

They are made by adding another element to a metal - that could be metal or non-metal.

Question 7

Why are alloys used rather than pure metals?

Answer 7

Pure metals have a regular arrangement of identical ions, the layers of ions can slide over each other. An alloy has different sized atoms making it more difficult for the layers to slide, so alloys are stronger.

Question 8

Alloys of iron are called what?

Answer 8

Steels.

Question 9

Why is iron alloyed with other metals to create steels?

Answer 9

It will rust fairly quickly on its own. Steel is also stronger.

Question 10

What are aluminium alloys used for and why?

Answer 10

It is used for aircraft manufacture, as it has a low density.

Question 11

What are gold alloys used for and why?

Answer 11

Jewellery- The purer the gold the higher the carat.

Question 12

How is magnalium made and what is it used for?

Answer 12

Aluminium + Magnesium: Used to make parts of cars and aeroplanes. Magnalium with a higher magnesium content is used in fireworks.

Question 13

Metals can corrode in the presence of what?

Answer 13

Oxygen and water to form metal oxides.

Question 14

Oxidation of metals results in what?

Answer 14

Corrosion.

Question 15

What is sacrificial protection?

Answer 15

This involves placing a more reactive metal with the iron. The water and oxygen react with this `sacrificial’ metal instead of the object you are protecting.

Question 16

What is galvanising?

Answer 16

An example of sacrificial protection. A coat of zinc is put onto an iron object to prevent rusting.

Question 17

What is electroplating?

Answer 17

This is when the surface of a metal is coated with another metal using electrolysis.

Question 18

How do you electroplate an object?

Answer 18

The cathode is the object you’re going to electroplate the anode is the bar of metal you’re using for the plating. Your electrolyte is a solution containing the metal ions of the metal you’re plating.

Question 19

How is electroplating useful?

Answer 19

• It stops metals reacting/corroding

- It improves the appearance of Jewellery and makes it look shiny

Question 20

What is titration?

Answer 20

Titration allows you to find the exact amount of acid needed to neutralise a given quantity of alkali or vice versa.

Question 21

Core Practical: Carry out an accurate acid-alkali titration, using burette, pipette and a suitable indicator

Answer 21

• Using a pipette, measure out a set volume of the alkali into a flask, Add a few drops of an indicator
• Fill a burette with a known concentration of acid
• Use the burette to add the acid to the alkali a bit at a time. Swirl the flask regularly.
• The indicator changes colour when all the alkali has been neutralised
• Record volume of acid used to neutralise alkali
• Repeat and take mean of results

Question 22

The concentration of a solution can be measured in what?

Answer 22

moles per dm³.

Question 23

What is the formula for concentration in mol dm³?

Answer 23

Concentration = number of moles ÷ volume of solution

Question 24

What is the formula for percentage yield?

Answer 24

Percentage yield = actual yield
——————— x100
theoretical yield

Question 25

What is the theoretical yield of a reaction?

Answer 25

The mass of product you'd make if all the reactants were converted to products.

Question 26

In real life, you never get 100% yield, why?

Answer 26

- Incomplete reaction - Practical losses: You always lose a bit when you transfer chemicals between containers - Unwanted reaction: Caused by impurities/change in reaction conditions

Question 27

What is the atom economy of a reaction?

Answer 27

It tells you what percentage of the mass of the reactants has been converted into your desired product when manufacturing a chemical.

Question 28

What is the formula for atom economy?

Answer 28

Atom Economy = total Mᵣ of desired products ——————————————— x100 total Mᵣ of all products

Question 29

A higher atom economy is better for what?

Answer 29

Profits and the environment.

Question 30

Explain why a particular reaction pathway is chosen to produce a specified product.

Answer 30

To give useful `by-products'.

Question 31

How can you reach equilibrium faster?

Answer 31

High temperature, concentration and pressure. As well as the use of a catalyst.

Question 32

The three main essential elements in fertilisers are what?

Answer 32

Nitrogen, phosphorus and potassium.

Question 33

What are the benefits of using ammonia fertilisers in comparison to traditional fertilisers?

Answer 33

You can control the composition of the chemicals in them. They are also soluble, so all the chemicals can be dissolved into the soil to reach the plants.

Question 34

Ammonia can be reacted with oxygen and water to make what?

Answer 34

Nitric acid.

Question 35

Ammonia and nitric acids react together to produce what?

Answer 35

The salt ammonium nitrate - a fertiliser.

Question 36

How do you prepare Ammonium sulphate in a lab?

Answer 36

- Add a few drops of methyl orange indicator to the ammonia - it'll turn yellow - Slowly add the dilute sulphuric acid from the burette into the ammonia, until the yellow changes red, this means the ammonia has been neutralised and you've got ammonium sulphate solution. - To get pure ammonium sulphate crystals, you must remove the methyl orange indicator. Note how much sulphuric acid it took to neutralise the ammonia, then repeat the titration using the volume of acid, but no indicator. - To get crystals gently evaporate solutions, leave it to crystallise, then filter out the crystals and leave them to dry.

Question 37

What is molar volume?

Answer 37

The volume occupied by one mole of a gas.

Question 38

What are the units of molar volume?

Answer 38

dm³ mol⁻¹

Question 39

What is the formula for molar volume?

Answer 39

molar volume = gas volume ÷ number of moles

Question 40

What is Avogadro's law?

Answer 40

It states that under the same conditions, the same number of moles of different gases all occupy the same volume.

Question 41

One mole of any gas always occupies how much space?

Answer 41

24 dm³.

Question 42

What is RTP?

Answer 42

RTP = 20°C and 1 atmosphere.

Question 43

What is the equation triangle for volume, moles and 24 dm³?

Answer 43

Volume | Moles x 24

Question 44

What is a fuel cell?

Answer 44

It is an electrical cell that's supplied with a fuel and oxygen and uses energy from the reaction between them to produce electrical energy efficiently.

Question 45

Chemical cells produce what?

Answer 45

A voltage across the cell, until all of one of the reactants has been used up.

Question 46

What happens in a hydrogen-oxygen fuel cell?

Answer 46

You can produce a voltage by reacting hydrogen and oxygen. The product of the reaction is water.

Question 47

What are the benefits of hydrogen-oxygen fuel cells?

Answer 47

- Efficient - No conventional pollutants - Less stages means there are less places for energy to be lost as heat

Question 48

What are the disadvantages of hydrogen-oxygen fuel cells?

Answer 48

- Hydrogen takes up more space than liquid - It's hard to store safely - Hydrogen fuel is made from fossil fuels