Some industrial gases are transported in high-pressure cylinders.
The table below gives chemical and physical information about five pure gases and one gaseous mixture, biogas.
| Name of gas | oxygen | helium | carbon dioxide | krypton | methane | biogas |
|---|---|---|---|---|---|---|
| Formula of gas | O2\text{O}_2O2 | He\text{He}He | CO2\text{CO}_2CO2 | Kr\text{Kr}Kr | CH4\text{CH}_4CH4 | |
| Relative formula mass (MrM_rMr) | 32 | 4 | 44 | 84 | 16 |
Cylinders containing flammable gases are designed with left-handed screw threads on their valves, whereas non-flammable gas cylinders use standard right-handed threads. Why is this distinction an advantage?
Which two gases in the table are noble gases?
Which gas in the table makes up approximately 21% of dry air?
Why is it not possible to give a single chemical formula or a fixed relative formula mass for biogas in the table?
Carbon dioxide and propane both have a relative formula mass of 44. State one hazard of propane that makes it much more dangerous to handle than carbon dioxide.
State which one of the gases in the table is: reacted with steam at high temperatures to produce hydrogen in industry.
State which one of the gases in the table is: used in high-performance double-glazing window units to provide thermal insulation.
State which one of the gases in the table is: used in liquid form to cool superconducting magnets in MRI scanners.
10 exam-style questions on Edexcel IGCSE Chemistry Gases in the atmosphere. Each one has a worked solution and a mark scheme showing where the marks go.