Chemistry of the atmosphere

Estimate the volume of oxygen in a $240\,\text{cm}^3$ sample of air.

A weather balloon contains $2.5\,\text{dm}^3$ of air. Estimate the volumes of nitrogen and oxygen in the balloon.

A student passes an air sample over a substance that removes oxygen. Its volume falls from $480$ to $386\,\text{cm}^3$. Calculate the percentage of the original sample that was oxygen and compare it with the accepted approximate value.

Name the gas thought to have made up most of the Earth's early atmosphere.

Explain how volcanic activity and cooling could produce an early atmosphere and then oceans.

A report claims that the exact composition of the atmosphere 4.6 billion years ago is known because modern volcanoes release carbon dioxide and water vapour. Evaluate this claim.

Name the process by which algae first increased atmospheric oxygen.

Explain why a large increase in photosynthetic organisms changes the proportions of both oxygen and carbon dioxide in the atmosphere.

A model shows atmospheric oxygen rising from $0.20\%\text{ to }8.6\%$ during a period when algae spread widely. Calculate how many times greater the final percentage is and explain why the data are consistent with the accepted account of atmospheric change.

State one process carried out by plants that lowered atmospheric carbon dioxide.

Explain two routes by which carbon from the early atmosphere became stored for long periods.

Compare the formation of limestone, coal, and crude oil or natural gas, and explain how each contributed to a lower proportion of atmospheric carbon dioxide.

Name two greenhouse gases present in the Earth's atmosphere.

Describe how short-wavelength and long-wavelength radiation are involved in the greenhouse effect.

Explain why increasing the concentration of carbon dioxide can raise the Earth's average surface temperature even though sunlight can still enter the atmosphere.

Give one human activity that increases carbon dioxide and one that increases methane in the atmosphere.

State two human activities that increase atmospheric carbon dioxide and two that increase atmospheric methane.

An online article uses six years of temperatures from one town to claim that human activity cannot affect global climate. The article was written by an energy company, gives no uncertainty, and has not been peer reviewed. Evaluate the quality of this evidence.

State one potential effect of global climate change.

Explain how an increase in average global temperature can increase the risk of coastal flooding.

A coastal wetland supports rare birds and protects a nearby town from storm waves. Discuss the scale, risk and environmental implications if climate change raises sea level in this region.

Define the carbon footprint of a product.

A music festival wants to reduce its carbon footprint. Describe two suitable actions and give one reason why each action may be limited.

A reusable product has life-cycle contributions of $18,\ 4,\ 30\text{ and }2\,\text{kg}$ from manufacture, transport, use and disposal, respectively. A redesign adds $3\,\text{kg}$ in manufacture but cuts transport emissions by $25\%$ and use emissions by $40\%$. Calculate the new footprint and the percentage reduction.

Name the toxic gas formed when a carbon-containing fuel burns with too little oxygen.

A fuel contains carbon, hydrogen and a small amount of sulfur. It burns in excess oxygen. Predict three products released by combustion and identify the element responsible for each.

A $2.0\,\text{kg}$ fuel sample contains 0.80% sulfur by mass. Assume every sulfur atom forms sulfur dioxide when the fuel burns. Calculate the mass of sulfur dioxide produced. Use $A_r(\text{S})=32$ and $A_r(\text{O})=16$.

Give two properties that make a carbon monoxide leak difficult for a person to detect.

Describe one effect of sulfur dioxide or oxides of nitrogen on humans, one effect on the environment, and one effect of particulates.

Near an industrial area, residents report breathing problems, a lake becomes more acidic, and less sunlight reaches the ground. Identify the likely pollutant groups and explain how the observations support your choices.