Chemistry 1a

Question 1

What are the symbols for:

a) . Calcium
b) . Carbon
c) . Sodium

Answer 1

a) . Ca
b) . C
c) . Na

Question 2

Which element’s properties are more similar to magnesium’s: calcium or iron?

Answer 2

Calcium’s.

Question 3

Describe how you would work out the electronic structure of an atom given its atomic number.

Answer 3

The atomic number tells you how many protons there are and the number of electrons in an atom is equal to the number of protons.

Question 4

Describe the process of ionic bonding.

Answer 4

• A compound which is formed from a metal and a non-metal
• The metal loses electrons to form positive ions and and the non-metal atoms gain electrons to become negative
• The opposite charges of the ions mean that they are strongly attracted to each other.

Question 5

What is covalent bonding?

Answer 5

• A compound formed from non-metals
• Each atom shares an electron with another atom
• Each atom has to make enough covalent bonds to fill up its outer shell

Question 6

What products are produced when limestone reacts with acid?

Answer 6

Calcium salt (depends on acid used), carbon dioxide and water.

Question 7

What is calcium hydroxide used for?

Answer 7

Used to test for carbon dioxide.

Question 8

Name three building materials made from limestone.

Answer 8

Cement, concrete and mortar.

Question 9

What is the name given to a rock that contains enough metal to make it worthwhile extracting?

Answer 9

An ore

Question 10

Explain why zinc can be extracted by reduction with carbon but magnesium can’t.

Answer 10

Metals that are higher than carbon in the reactivity series cannot be extracted by reduction with carbon, which is why magnesium can’t. However, metals below carbon in the reactivity series can be extracted by reduction with carbon because carbon can only take away the oxygen from metals which are less reactive than it, like zinc.

Question 11

What is reduction with carbon?

Answer 11

When oxygen is removed from the metal so the products are a metal and carbon dioxide.

Question 12

Give a reason why aluminium is an expensive metal.

Answer 12

Aluminium is extracted from its ore through the process of electrolysis, which is expensive and requires a lot of energy for it to happen.

Question 13

What is electrolysis?

Answer 13

The breaking down of a substance using electricity.

Question 14

Describe the process of purifying copper by electrolysis.

Answer 14

1. Electrons are pulled off copper atoms at the positive electrode, causing them to go into the solution as Cu2+ ions.
2. Cu2+ ions near the negative electrode gain electrons and turn back into copper atoms
3. The impurities are dropped at the positive electrodes as a sludge, whilst pure copper atoms bond to the negative electrode.

Question 15

Describe how scrap iron is used to displace copper from the solution.

Answer 15

1. If you put a more reactive metal into a solution of a dissolved meta compound, the reactive metal will replace the less reactive metal in the compound.
2. Scrap iron is more reactive than copper, you’ll end up with iron sulfate solution and copper metal.
3. It is really useful because iron is cheap but copper is expensive.

Question 16

What is the name of the method where plants are used to extract metals from soil?

Answer 16

Phytomining.

Question 17

Give three properties of metals.

Answer 17

1. They are strong
2. Great at conducting heat
3. Conduct electricity well.

Question 18

Briefly describe two problems with metals.

Answer 18

1. Some corrode when they are exposed to air and water and lose their strength and hardness
2. They can become ‘tired’ when stresses and strains re repeatedly put on them over time. This is known as metal fatigue and leads to metal breaking

Question 19

What is the problem with using pure iron?

Answer 19

It has a regular arrangement which makes it easy for the layers of atoms to slide over each other. This makes iron soft, easily shaped and far too bendy for normal uses.

Question 20

Give two examples of alloys and say what is in them.

Answer 20

1. Bronze, made of copper and tin

2. Cupronickel, made of copper and nickel

Question 21

What does crude oil consist of?

Answer 21

A mixture of different compounds. The compounds are hydrocarbon molecules.

Question 22

What does fractional distillation do to crude oil?

Answer 22

It splits crude oil into separate groups of hydrocarbons.

Question 23

What happens in a fractionating column?

Answer 23

As the oil travels up the column, the groups of hydrocarbons become smaller.

Question 24

What is the general formula for an alkane?

Answer 24

C (2) H (2n+2)

Question 25

Is a short-chain hydrocarbon more viscous than a long-chain hydrocarbon? Is it more volatile?

Answer 25

No, it is less viscous than a long-chain hydrocarbon but it is more volatile. The shorter the hydrocarbon, the more flammable it is.

Question 26

What does the term ‘volatile’ mean?

Answer 26

Something that turns into a gas. The more volatile it is, the lower the temperature it takes to turn it into a gas.

Question 27

Name three pollutants released into the atmosphere when fuels are burned.

Answer 27

Sulfur dioxide, oxides of nitrogen and carbon dioxide.

Question 28

List three ways of reducing acid rain.

Answer 28

1. Sulfur can be removed from fuels before they are burnt
2. Reducing emissions of air pollutants that cause acid rain
3. Reducing our usage of fossil fuels

Question 29

Has the theory of global warming been proven?

Answer 29

Yes, although some scientists believe the change is not real and blame it on inaccurate recording equipment.

Question 30

List three alternative ways of powering cars.

Answer 30

1. Ethanol
2. Biodiesel
3. Hydrogen gas

Question 31

What are the pros and cons of the use of ethanol as an alternative fuel?

Answer 31

+ The CO2 released when it is burnt was taken in by the plant as it grew so it is carbon neutral
+ The only other product is water
- Engines need to be converted before they’ll work with ethanol fuels
- Ethanol fuel is not widely available
- Farmers may switch to growing crops to make ethanol instead of food so food prices may increase.

Question 32

What are the pros and cons of the use of biodiesel as an alternative fuel?

Answer 32

+ It is carbon neutral
+ Engines do not need to be converted
+ It produces much less sulfur dioxide and particulates
- We cannot make enough to completely replace diesel
- It is expensive to make
- It could increase food process like using more ethanol could

Question 33

What are the pros and cons of using hydrogen gas as an alternative fuel?

Answer 33

+ It combines with air to form water so it is very clean

• You need a special, expensive engine to use it
• It is not widely available
• You still need to use energy from another source to make it
• Hydrogen is hard to store because it is explosive