chem-10 Flashcards
What are the uses of earths resources
Humans use the Earth’s natural resources for a number of purposes, including:
energy and fuels for warmth
building materials for shelter
food through farming
fuels for transport
materials for clothing
Whats the problems with using earths resources
The human population is growing very quickly and many people argue that humans are using up the Earth’s finite resources at a rate which is too fast and therefore unsustainable.
Chemists try to improve agriculture and industrial processes to provide new products that allow humans to meet their needs. It is essential that this is done in a sustainable way. This means that future generations of humans must also be able to meet their own needs. In other words, we must not use up all of the resources.
explain finite resources and renewable resources
Finite resources from the Earth’s crust, oceans and atmosphere will one day run out. They can be processed to provide energy and useful materials. Renewable resources are those which will not run out in the foreseeable future.
Give an example of a finite and renewable source
One of the most important finite resources in the crust is crude oil. Crude oil is processed through fractional distillation and cracking to produce a wide variety of useful chemicals. Sea water is a renewable resource because there is such a large amount of it that humans will not use it all up.
In some cases natural products can be supplemented or replaced by agriculture and synthetic products. give an example of this
until 1910 all fertilisers were obtained from natural resources such as manure.
However, the Haber process enabled humans to produce fertilisers from nitrogen in the air, and has allowed synthetic fertilisers to be produced. Synthetic fertilisers have allowed intensive farming to become widespread, which has meant that we can produce enough food to support the growing world population
In some cases natural products can be supplemented or replaced by agriculture and synthetic products. give an example of this
until 1910 all fertilisers were obtained from natural resources such as manure.
However, the Haber process enabled humans to produce fertilisers from nitrogen in the air, and has allowed synthetic fertilisers to be produced. Synthetic fertilisers have allowed intensive farming to become widespread, which has meant that we can produce enough food to support the growing world population
What is portable water
Water is essential for life. Water that is safe for humans to drink is called potable water. Potable water is not pure water because it almost always contains dissolved impurities.
For water to be potable, it must have sufficiently low levels of dissolved salts and microbes. This is because:
dissolved salts can sometimes be harmful for humans
microbes can cause illnesses
What is water in the uk like
The methods used to make water potable depend on where you live. Starting with fresh water is easier than sea water, as removing the large amount of sodium chloride present in sea water requires a lot of energy.
In the UK, rain provides enough fresh water to meet the needs of the population. Sometimes during the summer months in some areas of the UK, water reserves run low and people are encouraged to conserve tap water by the use of hosepipe bans.
Rainwater collects in rivers, lakes and in rocks underground. This water contains low levels of dissolved substances.
Most potable water in the UK is produced from naturally occurring fresh water by:
passing the water through filter beds to remove insoluble particles
sterilising the water to kill microbes
The methods used for sterilisation include chlorine, ozone and ultraviolet light.
What’s the method to turn sea water into portable water
Potable water can be made from sea water, through a process known as desalination. It is preferable to make potable water from fresh water reserves rather than from sea water. This is because removing the large amount of sodium chloride (35 grams in every kilogram of sea water) requires a lot of energy.
Desalination can be done by distillation and by reserve osmosis
What is distilltion
Sea water is heated until it boils. The salt remains in the liquid, and the steam is pure water. The steam is cooled and condensed to make potable water.
Distillation requires a lot of energy to boil the water, and also to cool the steam down to condense it. The waste water is very salty and can be difficult to dispose of in a sustainable way which does not harm marine ecosystems.
what is reverse osmosis
Water is put under high pressure and passed through a membrane which has tiny pores (holes) in it. The pores allow water molecules through, but prevent most ions and molecules from passing through. Reverse osmosis requires expensive membranes and also produces a large volume of waste water, so its efficiency is often quite low.
how is waste water treated
Waste water from homes, industry and agriculture must be treated before being released into the environment. Here are some examples of pollutants which might be present in waste water:
human waste contains harmful bacteria and high levels of nitrogen compounds which can harm aquatic ecosystems
industrial waste water may contain harmful chemicals such as toxic metal compounds
agricultural waste water may contain fertilisers or pesticides which can disrupt sensitive ecosystems
Sewage treatment involves the following steps:
screening and grit removal to remove large particles
sedimentation allows tiny particles to settle out from still water, which produces sewage sludge and effluent (the liquid which remains on top)
the sewage sludge is digested anaerobically by specific bacteria
the effluent is treated with aerobic bacteria to reduce the volume of solid waste
