10 2 air quality and climate

The two main gases in the atmosphere are nitrogen (about four-fifths) and oxygen (about one-fifth).

Air pollutants are gases present in the atmosphere due to human activities that are not naturally present in significant quantities.

A major source of carbon dioxide pollution is the complete combustion of carbon-containing fuels such as fossil fuels.

False. Carbon monoxide is produced by incomplete combustion of carbon-containing fuels.

Particulates are small particles of carbon (soot) produced by the incomplete combustion of carbon-containing fuels.

Two sources of methane pollution are waste gases from digestive processes of animals and decomposition of vegetation.

Oxides of nitrogen are formed by the reaction of nitrogen with oxygen in the presence of very high temperatures, such as in car engines or during lightning.

The main source of sulfur dioxide pollution is power stations burning fossil fuels containing sulfur compounds.

Acid rain is rainwater that has become acidic due to dissolved pollutants such as oxides of nitrogen and sulfur dioxide.

False. The present composition of gases in the atmosphere has not changed significantly in 200 million years.

The equation to form sulfur dioxide from sulfur is: S + O2 → SO2

The greenhouse effect is the process where greenhouse gases in the atmosphere absorb and re-emit thermal energy, trapping heat within the Earth's atmosphere.

Two main greenhouse gases are carbon dioxide and methane.

False. The natural greenhouse effect keeps the Earth warm, but the enhanced greenhouse effect due to increased greenhouse gas concentrations causes global warming.

Global warming is the rise in Earth's average temperature due to increased concentrations of greenhouse gases in the atmosphere.

Consequences of global warming include:

The enhanced greenhouse effect is the process where increased concentrations of greenhouse gases in the atmosphere trap more thermal energy, causing the Earth's average temperature to rise.

The greenhouse effect works by greenhouse gases absorbing thermal energy emitted from Earth's surface and re-emitting it in all directions, reducing the amount of heat lost to space.

False. Some thermal energy from the Sun is reflected from the Earth's surface.

Climate change is the long-term alteration of temperature and typical weather patterns due to global warming.

Global warming can lead to the spread of diseases by creating warmer climates that are more suitable for disease-carrying organisms to survive and spread.

Two strategies to reduce carbon dioxide emissions are:

Flue gas desulfurisation is a process used to reduce sulfur dioxide emissions by spraying waste gases from power stations with a slurry of calcium compounds.

False. Catalytic converters in vehicles are used to remove oxides of nitrogen.

The main way to reduce sulfur dioxide emissions is through flue gas desulfurisation.

A catalytic converter is a device fitted in car exhaust systems that contains transition metal catalysts to render pollutant gases harmless.

Two reactions that occur in a catalytic converter are the oxidation of carbon monoxide to carbon dioxide and the reduction of oxides of nitrogen to nitrogen gas.

True. Platinum and rhodium are examples of catalysts used in catalytic converters.

The purpose of the honeycomb structure in catalytic converters is to increase the surface area available for reaction.

The equation for the reaction of nitrogen monoxide and carbon monoxide in a catalytic converter is: 2NO + 2CO → N2 + 2CO2

Photosynthesis is an endothermic reaction where carbon dioxide and water are converted into glucose and oxygen using energy from light and chlorophyll.

The reactants in photosynthesis are carbon dioxide and water.

The products of photosynthesis are glucose and oxygen.

False. Photosynthesis is an endothermic reaction.

Chlorophyll is found in chloroplasts in plants.

The balanced symbol equation for photosynthesis is: 6CO2 + 6H2O → C6H12O6 + 6O2

The word equation for photosynthesis is: carbon dioxide + water → glucose + oxygen

Light provides the energy required for the photosynthesis reaction to occur.

False. Chlorophyll is necessary for photosynthesis to occur.

Photosynthesis is an endothermic reaction, meaning it takes in energy from the environment.