Gases In The Atmosphere Flashcards
What are the volumes of the most abundant gases in dry air?
Nitrogen: 78%
Oxygen: 21%
Argon: 0.9%
Carbon dioxide: 0.04%
What are the greenhouse gases?
Carbon dioxide, water vapour and methane
Combustion of magnesium in oxygen
Magnesium reacts with oxygen producing a bright white flame leaving behind a white ash of magnesium oxide (alkaline when dissolved in water).
Combustion of Hydrogen in oxygen
Exothermic, burns easily, produces a pale blue flame and by burning hydrogen; water is produced (neutral pH).
Combustion of Sulfur in oxygen
Burns with a blue flame to produce sulfur dioxide (which is a colourless, poisonous gas and is acidic when dissolved in water).
What can combustion reactions also be classified as?
Oxidation reactions
What is thermal decomposition?
Thermal decomposition is the term used to describe reactions where a substance breaks down due to the action of heat.
Give an example of thermal decomposition.
One such reaction is the thermal decomposition of metal carbonates.
Which carbonates of metal tend to decompose on heating to produce the metal oxide and carbon dioxide gas?
Carbonates of metals from the lower half of the reactivity series tend to decompose on heating to produce the metal oxide and carbon dioxide gas.
What is the general formula for the thermal decomposition of metal carbonates?
metal carbonate → metal oxide + carbon dioxide
Why is copper (II) carbonate suitable for thermal decomposition?
Copper (II) carbonate is suitable for thermal decomposition as it occurs readily on heating.
What is copper (II) carbonate?
Copper(II) carbonate is a green powder.
How does Copper (II) carbonate change as it undergoes thermal decomposition?
When Copper (II) carbonate undergoes thermal decomposition, it slowly darkens from a green powder to produce another substance; black copper (II) oxide.
How can the carbon dioxide given off be tested?
The carbon dioxide given off can be tested by passing the gas through limewater and looking for it to turn milky/cloudy.
What is the chemical equation for thermal decomposition of copper (II) carbonate? (Include state symbols)
CuCO3 (s) → CuO (s)+ CO2 (g)
What is the word equation for the thermal decomposition of copper (II) carbonate?
copper(II) carbonate → copper(II) oxide + carbon dioxide
Where are greenhouse gases found?
Greenhouse gases are found in the atmosphere in trace amounts: water vapour, carbon dioxide and and methane
What are the greenhouse gases (in learning specification)?
Water vapour, carbon dioxide and methane
Explain how the greenhouse gas effect begins
- Energy from the sun travels to the Earth as short wavelength radiations for example: ultraviolet and visible light. Some of the short wavelength radiation reflect back into space but most of it passes easily through the atmosphere as short wavelength radiation does not react strongly with the gas molecules in the atmosphere. The energy of the radiation is now absorbed when it reaches the surface of the Earth. The surface of the Earth now radiates the energy as long wavelength radiation (infrared), some of the long wavelength radiation interacts with the greenhouse gas molecules in the atmosphere. Causing the temperature of the atmosphere to increase.
What do the greenhouse gases ensure?
They ensure that the temperature on Earth is warm enough (mean global temperature = around 15oC) to support life.
What is the mean global temperature?
Around 15oC
What would happen without the greenhouse effect?
The Earth would swing between extreme heat and extreme cold.
What do greenhouse gases absorb?
Greenhouse gases absorb infrared radiations.
How does carbon dioxide in our atmosphere increase?
By burning fossils fuels
Why do we burn fossil fuels?
We burn fossil fuels for energy.
Give some examples of why we burn fossil fuels.
Coal for electricity, petrol and diesel to power cars and gas to heat our homes.
How could deforestation lead to more carbon dioxide in our atmosphere?
Trees absorb carbon dioxide and by cutting trees, less carbon dioxide will be absorbed. As well as when forests are cleared or burnt, stored carbon dioxide inside the trees is released into the atmosphere.
Where is methane released?
Methane is released in agriculture (farm animals produce methane during digestion) as well as when we produce huge amounts of waste (releases methane as it is decomposed by micro-organisms)
Summarize why greenhouse gases cause the Earth to warm up
Greenhouse gases trap some of the Sun’s radiation causing the Earth to warm up
What do rising temperatures lead to?
An increase of melting polar ice sheets and glaciers which will then lead to increased sea levels (extra water in the seas). As well as when water in the ocean warm up, it expands (volume increases). It will also lead to changes in the distribution of animals.