# Gas

## Key Stage 2

### Meaning

Gas is a state of matter that can change size and shape to fit any container.

Most gases are invisible but we can feel them.
When the air moves we call it the wind.
 Cannot hold their shape. Fit the shape of their container. Can be poured and will flow.
 Gases can be squashed into a smaller size.

Examples of gas materials:

• Air (A mixture of gases, mostly nitrogen and oxygen)
• Steam

## Key Stage 3

### Meaning

Gas is a State of Matter in which the particles are separated by large distances and can move freely.

 Gases cannot hold their shape because the particles are free to move. Gases fit the shape of their containers because the particles are free to move. A gas can be poured and will flow because the particles are free to move.
 Gas can be squashed into a smaller size because the particles are spread apart.

## Key Stage 4 Foundation

### Meaning

Gas is a State of Matter in which the particles are separated by large distances and can move freely.

When a substance is in its gaseous state it is always less dense than in its liquid or solid state due to the particles in a gas being spread far apart from each other.
A substance which is gaseous at room temperature has a smaller force of attraction between particles than a substance which is liquid or solid at room temperature.
 Particle Diagram Particle Arrangement Property Particles are free to move in all directions. Gases fit the size of their container. Gases fit the shape of their container. Convection happens most easily in gases. Particles are spread apart. Gases can be compressed into a smaller volume. Sound passes through gases slower than liquids and solids. Thermal Conduction is very poor in a gases.

## Key Stage 4 Higher

### Molar Gas Volume

At Standard Temperature and Pressure (20°C and 101,000Pa) the volume of one mole of gas is 24 dm3.
The volume of gas required or produced in a chemical reaction can be calculated from the mass of the gas and its Relative Formula Mass.

#### Example Calculations

 Calculate the volume of 4g of Hydrogen gas. Calculate the volume of 8g of Oxygen gas. Calculate the volume of 20g of Methane gas. 1.Find the Relative Formula Mass of the gas. Chemical Formula of Hydrogen = H2 Relative Formula Mass of H2 = 2g 1.Find the Relative Formula Mass of the gas. Chemical Formula of Oxygen = O2 Relative Atomic Mass of Oxygen = 16g Relative Formula Mass of O2 = 32g 1.Find the Relative Formula Mass of the gas. Chemical Formula of Methane = CH4 Relative Atomic Mass of Carbon = 12g Relative Formula Mass of CH4 = 16g 2. Calculate the number of moles of gas. 1 mole = 2g No. Moles = $$\frac{Mass}{M_r}$$ No. Moles = $$\frac{4}{2}$$ No. Moles = 2mol 2. Calculate the number of moles of gas. 1 mole = 32g No. Moles = $$\frac{Mass}{M_r}$$ No. Moles = $$\frac{8}{32}$$ No. Moles = 0.25 mol 2. Calculate the number of moles of gas. 1 mole = 16g No. Moles = $$\frac{Mass}{M_r}$$ No. Moles = $$\frac{20}{16}$$ No. Moles = 1.25 mol 3. Find the volume in dm3. Volume = 24 x (number of moles) Volume = 24 x (2) Volume = 48dm3 3. Find the volume in dm3. Volume = 24 x (number of moles) Volume = 24 x (0.25) Volume = 6dm3 3. Find the volume in dm3. Volume = 24 x (number of moles) Volume = 24 x (1.25) Volume = 30dm3
 Calculate the mass of 12dm3 of Hydrogen gas. Calculate the mass of 36dm3 of Nitrogen gas. Calculate the mass of 18dm3 of Ethane gas. 1.Find the Relative Formula Mass of the gas. Chemical Formula of Hydrogen = H2 Relative Formula Mass of H2 = 2g 1.Find the Relative Formula Mass of the gas. Chemical Formula of Nitrogen = N2 Relative Atomic Mass of Nitrogen = 14g Relative Formula Mass of N2 = 28g 1.Find the Relative Formula Mass of the gas. Chemical Formula of Ethane = C2H6 Relative Atomic Mass of Carbon = 12g Relative Formula Mass of C2H6 = 30g 2. Calculate the number of moles of gas. Volume = 24 x (number of moles) 12 = 24 x (number of moles) Number of moles = 12/24 Number of moles = 0.5 2. Calculate the number of moles of gas. Volume = 24 x (number of moles) 36 = 24 x (number of moles) Number of moles = 36/24 Number of moles = 1.5 2. Calculate the number of moles of gas. Volume = 24 x (number of moles) 12 = 24 x (number of moles) Number of moles = 18/24 Number of moles = 0.75 3. Find the mass of gas from the number of moles. No. Moles = $$\frac{Mass}{M_r}$$ 0.5 = $$\frac{Mass}{2}$$ Mass = $$0.5\times2$$ Mass = 1g Volume = 48dm3 3. Find the mass of gas from the number of moles. No. Moles = $$\frac{Mass}{M_r}$$ 1.5 = $$\frac{Mass}{28}$$ Mass = $$1.5\times28$$ Mass = 42g 3. Find the mass of gas from the number of moles. No. Moles = $$\frac{Mass}{M_r}$$ 0.75 = $$\frac{Mass}{30}$$ Mass = $$0.75\times30$$ Mass = 22.5g

### References

#### AQA

Gas, pages 13, 34-5, 82-5, 96-101, GCSE Physics; Student Book, Collins, AQA
Gas; pressure, pages 82-5, 96-9, 257, GCSE Physics; Student Book, Collins, AQA
Gas; volume, page 98, GCSE Physics; Student Book, Collins, AQA
Gases pages 36, 37, 46, 107, GCSE Chemistry; The Revision Guide, CGP, AQA
Gases, page 107, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
Gases, page 71, GCSE Physics, Hodder, AQA
Gases, page 88, GCSE Chemistry; The Revision Guide, CGP, AQA
Gases, page 97, GCSE Combined Science Trilogy; Physics, CGP, AQA
Gases, pages 100, 101, 124, GCSE Chemistry, CGP, AQA
Gases, pages 164-5, 323, GCSE Combined Science Trilogy 1, Hodder, AQA
Gases, pages 6, 36-37, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Gases, pages 78-79, 83, 86-89, GCSE Physics; Third Edition, Oxford University Press, AQA
Gases, pages 98, 99, GCSE Combined Science Trilogy; Chemistry, CGP, AQA
Gases; analysis, pages 184-185, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Gases; atmosphere, pages 194-205, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Gases; density of, page 323, GCSE Combined Science Trilogy 1, Hodder, AQA
Gases; gas pressure, page 193, GCSE Combined Science; The Revision Guide, CGP, AQA
Gases; gas pressure, page 41, GCSE Physics; The Revision Guide, CGP, AQA
Gases; gas syringes, pages 140, 232, GCSE Combined Science; The Revision Guide, CGP, AQA
Gases; greenhouse effect, pages 198-202, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Gases; Greenhouse gases, pages 170-3, GCSE Combined Science Trilogy 2, Hodder, AQA
Gases; identification of, page 207, GCSE Chemistry, Hodder, AQA
Gases; Identification of, pages 160, GCSE Combined Science Trilogy 2, Hodder, AQA
Gases; In the atmosphere, pages 167, GCSE Combined Science Trilogy 2, Hodder, AQA
Gases; measuring volumes, pages 140, 232, 237, GCSE Combined Science; The Revision Guide, CGP, AQA
Gases; natural gas, page 178, GCSE Combined Science; The Revision Guide, CGP, AQA
Gases; natural gas, pages 18, 21, GCSE Physics; The Revision Guide, CGP, AQA
Gases; natural gas, pages 45, 46 54, 56, GCSE Combined Science Trilogy; Physics, CGP, AQA
Gases; natural gas, pages 47, 48, 56, 58, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
Gases; particle model of, pages 330-1, GCSE Combined Science Trilogy 1, Hodder, AQA
Gases; particle model of, pages 78-80, 85-6, GCSE Physics, Hodder, AQA
Gases; particle motion, page 104, GCSE Combined Science Trilogy; Physics, CGP, AQA
Gases; particle motion, page 193, GCSE Combined Science; The Revision Guide, CGP, AQA
Gases; particle motion, pages 114, 115, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
Gases; particle motion, pages 38, 41, GCSE Physics; The Revision Guide, CGP, AQA
Gases; pressure, page 104, GCSE Combined Science Trilogy; Physics, CGP, AQA
Gases; pressure, page 36, GCSE Chemistry; Third Edition, Oxford University Press, AQA
Gases; pressure, pages 114, 115, 169, 171, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
Gases; states of matter, pages 106, 107, 110-112, GCSE Physics; The Complete 9-1 Course for AQA, CGP, AQA
Gases; states of matter, pages 121, 122, 193, 195, GCSE Combined Science; The Revision Guide, CGP, AQA
Gases; states of matter, pages 38-40, GCSE Physics; The Revision Guide, CGP, AQA
Gases; states of matter, pages 96, 97, 100-102, GCSE Combined Science Trilogy; Physics, CGP, AQA
Gases; tests for, page 153, GCSE Combined Science; The Revision Guide, CGP, AQA
Gases; Volume and mass measurement, pages 120, GCSE Combined Science Trilogy 2, Hodder, AQA
Gases; volume, pages 78-79, 129, GCSE Chemistry; Third Edition, Oxford University Press, AQA

#### Edexcel

Gases, molar volumes of, pages 118-119, GCSE Chemistry, Pearson, Edexcel
Gases, page 300, GCSE Physics, CGP, Edexcel
Gases, pages 34, 35, GCSE Chemistry; The Revision Guide, CGP, Edexcel
Gases, pages 96, 98, GCSE Chemistry, CGP, Edexcel
Gases, pages 97, 98, GCSE Combined Science; The Revision Guide, CGP, Edexcel
Gases; doing work, page 312, GCSE Physics, CGP, Edexcel
Gases; pressure, page 424, GCSE Combined Science, Pearson Edexcel
Gases; pressure, pages 192, 194-195, GCSE Physics, Pearson Edexcel
Gases; pressure, pages 310-312, 319, GCSE Physics, CGP, Edexcel
Gases; temperature, page 192, GCSE Physics, Pearson Edexcel
Gases; temperature, page 424, GCSE Combined Science, Pearson Edexcel
Gases; volume, pages 194-195, GCSE Physics, Pearson Edexcel

#### OCR

Gases, page 12, Gateway GCSE Chemistry; The Revision Guide, CGP, OCR
Gases, page 18, Gateway GCSE Chemistry, Oxford, OCR
Gases, pages 14, 17, 18, Gateway GCSE Physics; The Revision Guide, CGP, OCR
Gases, pages 82, 152, 155, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR
Gases; atmosphere, pages 252-257, Gateway GCSE Chemistry, Oxford, OCR
Gases; calculating amounts, pages 170-171, Gateway GCSE Chemistry, Oxford, OCR
Gases; changing state, pages 76-77, Gateway GCSE Chemistry, Oxford, OCR
Gases; collecting, pages 128, 222, Gateway GCSE Combined Science; The Revision Guide, CGP, OCR
Gases; collection, pages 265, 267, Gateway GCSE Chemistry, Oxford, OCR
Gases; detection, pages 146-147, 265, 267, Gateway GCSE Chemistry, Oxford, OCR
Gases; pressure in, pages 17, 18, Gateway GCSE Physics; The Revision Guide, CGP, OCR
Gases; pressure, page 179, Gateway GCSE Chemistry, Oxford, OCR
Gases; refined crude oil, page 239, Gateway GCSE Chemistry, Oxford, OCR
Gases; volume, pages 170-171, 174, Gateway GCSE Chemistry, Oxford, OCR