Chemistry

Question 1

What is combustion?

Answer 1

Combustion is when a fuel burns.

Question 2

What is the word equation for the combustion of a hydrocarbon?

Answer 2

Hydrocarbon + oxygen —> water + carbon dioxide

Question 3

What is the word equation for a metal oxidation reaction?

Answer 3

Metal + Oxygen —> Metal Oxide

Question 4

What is the law of conservation of mass in reactions?

Answer 4

In a reaction, the mass of the reactants is always the same as the mass of the products. Sometimes, it appears to lose mass because the products of the reaction are lost in the air. (water vapour)

Question 5

What are the three factors that are needed for a fire to burn?

Answer 5

• Oxygen
• Fuel
• Heat

Question 6

What is the word equation for incomplete combustion?

Why is this reaction dangerous?

Answer 6

Hydrocarbon + oxygen —> carbon dioxide + water + carbon monoxide + carbon

This reaction causes pollution from the carbon dioxide, carbon monoxide (poisonous) and carbon. They harm habitats and their organisms.

Question 7

How can acid rain be made?

Answer 7

Acid rain is made of dissolved sulfur dioxide and nigtrogen oxides, causing pollution. Nitrogen oxides are caused when vehicle engines temperature increases and nitrogen gas from the air reacts with oxygen.

Question 8

How does carbon dioxide cause the greenhouse effect and climate change?

Answer 8

Carbon dioxide is a greenhouse gas. It increases the temperature of the Earth’s surface (global warming). Energy from the sun goes to the earth. The earth absorbs most of the energy increasing the temperature. Some energy is reflected off the earth and some is taken in then released. When the earth releases this energy, carbon dioxide is absorbing it and transferring it back to the earth.

Question 9

What is the difference between an element and a compound?

Answer 9

A compund is made up of 2 or more different atoms bonded together. An element is a substance made from only one type of atom.

Question 10

Name some signs that a chemical reaction is taking place.

Answer 10

• Colour change
• Gas produced
• Solid formed from solution
• Energy change

Question 11

How do you make an element symbol?

Answer 11

They are either a single or double letter. They always start with a capital letter. You put the amount of the element at the bottom of the number e.g. CO₂ . If you had 8 sodium atoms and 8 chlorine atoms, the ratio is 1:1 so the formula has no numbers, NaCI.

Question 12

Which elements on this table are metal?

Answer 12

Question 13

What are the similarities of alkali metals?

Answer 13

Alkali metals react with water to form an alkaline.

Question 14

What are the similarities of halogens?

Answer 14

Halogens are all reactive non-metals.

Question 15

What are the similarities of noble gases?

Answer 15

Noble gases are all very unreactive gases.

Question 16

What are the physical properties of metals and also of non-metals?

Answer 16

Question 17

When we talk about the chemical properties of metals, what are we referring to?

Answer 17

Their reactions with other substances.

For example, metals can react with many non-metals:

eg. calcium + chlorine →calcium chloride

(Note: When naming a compound the ending of the non-metal is changed to _ide)

Question 18

What does a reactive metal do. Give an example of a reactive metal.

Answer 18

React very quickly. Calcium is a reactive metal.

Question 19

What does an unreactive metal do? Give an example of a very unreactive metal.

Answer 19

They do not react quickly. Gold is a very unreactive metal.

Question 20

Which metal is used in electrical wires and why?

Answer 20

Copper. It is flexible and a good conductor of electricity.

Question 21

What metal is used for roof sheets and why?

Answer 21

Copper. Because it is malleable and doesn’t react quickly in water.

Question 22

Some metals act as catalysts. What does that mean?

Answer 22

They are substances that speed up the chemical reactions without being used up themselves.

Question 23

Catalysts have many uses. For example one is used in catalytic converters in cars. Which metal is this?

Answer 23

Platinum

Question 24

What is the word equation for the reaction of metals with oxygen?

Answer 24

metal + oxygen → metal oxide

Question 25

What is the name given to the reaction of metals with oxygen? (There are 2 options, can you name both?)

Answer 25

This is called an oxidation or corrosion reaction

Question 26

Can you name a metal that reacts quickly with water and oxidises immediately when scratched?

Answer 26

Sodium

Question 27

Can you name a metal that changes colour very slowly as it eacts with oxygen?

Answer 27

Silver

Question 28

What name is given to the corrosion of iron?

Answer 28

Rusting

Question 29

Why does rusting or rust destroy iron structures?

Answer 29

Because rust is weak and crumbly.

Question 30

What 2 things must be present for iron to rust? Can you put this into a word equation?

Answer 30

Water and oxygen.

iron + water + oxygen → iron hydroxide

Question 31

What can we do to iron to provide a barrier to rusting?

Answer 31

Coat the iron with paint or plastic etc. This acts as a barrier to oxygen and water and stops it rusting.

Question 32

Some metals react with cold water.. These form a metal hydroxide (an alkaline solution) and hydrogen gas. Can you put this into a word equation?

Answer 32

metal + water → metal hydroxide + hydrogen

Question 33

Can you write the following equation using symbols?

sodium + water → sodium hydroxide + hydrogen

Answer 33

2Na + 2H₂O → 2NaOH + H₂

Question 34

When testing for hydrogen gas, when it burns what does it do?

Answer 34

It burns with a squeaky pop

Question 35

Which groups of metals react with acids?

Answer 35

Metals that react with water react very quickly with acids.

Some metals that don’t react with water do react with acids.

Question 36

When metals react with acids, what do they produce? And can you write the equation?

Answer 36

Hydrogen and a salt.

metal + acid → salt + hydrogen

Question 37

The name of the salt formed when metals react with acid depends on the name of the acid. What salts are made from…

• hydrochloric acid
• sulfuric acid
• nitric acid

Answer 37

• hydrocloric acid → chlorides
• sulfuric acid → sulfates
• nitric acid → nitrates

Question 38

Change the following equation in symbols to words:

Mg + H₂SO₄ → MgSO₄ + H₂

Answer 38

magnesium + sulfuric acid → magnesium sulfate + hydrogen

Question 39

What are Alloys?

Answer 39

Alloys are mixtures of metals with one or more other elements. They had different properties from the pure metal and so can be more useful.

eg Steel, an alloy of iron, is stronger and does not rust as quickly

Question 40

What is the difference in the melting points between pure metals as opposed to alloys?

Answer 40

Pure metals have a fixed, precise melting point where as alloys have a lower melting point and melt over a range of temperatures. Melting points can therefore be used to identify pure metals.

Question 41

Why are alloys usually harder than pure metals?

Answer 41

Because the different sized atoms disrupt the regular structure making it harder for the layers of atoms to slip over each other.

Question 42

Can you describe or draw the rock cycle?

Answer 42

Question 43

What are rocks made of?

Answer 43

Grains

Question 44

Each grain in a rock is made of a naturally occurring compound called a …..?

Answer 44

Mineral

Question 45

What name is given to the description of the size and shape of the grains that make up a rock?

Answer 45

The Texture

Question 46

Give 4 examples of Sedimentary rock.

Are they made up of grains or crystals?

Are they hard or soft?

Are they porous?

Answer 46

• limestone
• sandstone
• mudstone
• chalk

Made up of separate grains

Often soft or crumbly

Often porous