gases in atmosphere Flashcards
What is the composition of air?
About four-fifths (approximately 80%) nitrogen and about one fifth (approximately 20%) oxygen, with small proportions of other gases including carbon dioxide, water vapour and trace quantities of noble gases.
How can the percentage of oxygen in air be determined?
By reacting a metal or non-metal with the oxygen in a fixed volume of air, such as burning phosphorus in a bell jar.
What happens to the water level when phosphorus burns in a bell jar?
The water level rises as the phosphorus uses up the oxygen inside the bell jar.
What is a disadvantage of using phosphorus in experiments to find oxygen percentage?
Phosphorus is toxic and hazardous, requiring careful handling.
What is the aim of the practical experiment to determine the percentage of oxygen in air?
To determine the percentage of oxygen in air using the oxidation of iron.
What is combustion?
The scientific word for burning, involving a chemical change where oxygen reacts with elements or compounds to produce oxides.
What are the products of magnesium combustion?
Magnesium oxide (white powder) and heat.
What is produced during the combustion of hydrogen?
Water.
What is the observation during the combustion of sulfur?
A blue flame and the production of a colourless, poisonous gas (sulfur dioxide).
What is thermal decomposition?
A reaction where a substance breaks down due to the action of heat.
What occurs during the thermal decomposition of metal carbonates?
They break down to produce metal oxides and carbon dioxide gas.
What is the equation for the thermal decomposition of copper(II) carbonate?
CuCO3 (s) → CuO (s) + CO2 (g)
What is the greenhouse effect?
The process by which greenhouse gases maintain the Earth’s temperature high enough to support life.
What are three major greenhouse gases?
- Carbon dioxide
- Methane
- Water vapour
What happens to short wavelength radiation emitted from the sun when it reaches Earth?
Some is absorbed, and some is re-emitted as long wavelength radiation.
What is the impact of increasing levels of carbon dioxide and methane?
They cause significant upset to the Earth’s natural conditions by trapping extra heat energy.
What is the difference between the greenhouse effect and the enhanced greenhouse effect?
The greenhouse effect maintains the mean global temperature, while the enhanced greenhouse effect, due to increased greenhouse gas concentrations, is leading to global warming.
