Use LEFT and RIGHT arrow keys to navigate between flashcards;
Use UP and DOWN arrow keys to flip the card;
H to show hint;
A reads text to speech;
38 Cards in this Set
- Front
- Back
Structure of the Earth |
Iron & nickel core, mantle, crust |
|
Tectonic plates |
Crust and upper mantle are cracked into large pieces called tectonic plates. They move around- few cm per year |
|
What shows the movement of tectonic plates? |
Magnetic clues in rocks. When tectonic plates move apart under the sea, exposed mantle rises up and a new crust solidifies. New crust is magnetised by Earth's magnetic field. Normal or reverse polarity. pattern of normal/reversed polarised rocks used to estimate age of parts of crust Track slow movement of plates |
|
Sedimentary rocks contain clues |
Look at features of rocks. Fossils- remains/imprints of dead organisms tells age of rock. Conditions it was formed in. Shells, ripples,shapes of grains (water-borne or air-blown) |
|
Minerals in the crust- formed by different processes |
Sedimentation, Evaporation, Dissolving, Erosion, Mountain building. Chemical industries grow. |
|
Describe Limestone |
-Sedimentary rock from seashells -over millions of years layers of sediment get buried. Weight pressing down squeezes out water -natural mineral cement |
|
Describe coal |
-Black in colour -Sedimentary -Mainly carbon -lots of impurities |
|
Where is salt found? |
Rock salt- salt and impurities, found in underground deposits. Massive deposits in Cheshire & Teeside, UK |
|
What is normal salt mining? |
Physical extraction of salt Rock salt is drilled, blasted, dug out, brought to surface. Mostly used on roads to stop ice forming. - salt can be seperated- flavour food, making chemicals |
|
What is solution mining? |
Water is injected into salt deposit. Dissolves to make brine. Pressure forces brine to surface. Brine stored in wells and pumped to refining plant. Impurities removed. Brine boiled, water evaporates, salt left. Most table salt, chemical production. |
|
How do these methods of mining salt impact the environment? |
Pollution- mining requires a lot of energy. Subsidence- land above collapse into holes Risk reduced by filled in caverns. |
|
Another method of obtaining salt |
in hot countries, evaporating seawater. Shallow pools, left in sun, salt is collected. Purest salt- almost 100% NaCl |
|
How is salt used in food production? |
To enhance flavour. Mostly in processed foods. As a preservative- when added to meat, kills bacteria |
|
What are health issues with the use of salt? |
High intake= High blood pressure, stroke, heart attacks Increases risks of stomach cancer, osteoporosis, renal failure. |
|
Government issues guidelines for salt intake |
Watchdogs, Food Standards agency. GDA risk assessments, advise the public. Food manufactures still include salt to support sales. Cost of reformulating recipes is great. |
|
How is salt important for the chemical industry? |
They electrolyse brine- they pass an electric current through it. Causes chemical change- splits solution into Hydrogen, Chlorine and Sodium Hydroxide. |
|
Electrolysis of Brine- 1) Chlorine What are the uses? |
Disinfectants Killing bacteria Household bleach Plastics HCL Insecticides |
|
Uses of hydrogen |
ammonia turning oils into fats- margarine fuels welding and metal cutting |
|
Uses of Sodium Hydroxide |
Very strong alkali Soap Ceramics Organic chemicals Paper pulp Oven cleaner Household bleach- when it reacts with Chlorine. |
|
Environmental impact of large scale electrolysis |
Pollution Uses finite resources Mercury and asbestos are used- they are toxic, can cause cancer, contaminate rivers |
|
Chlorine used for water treatment |
small amounts added to water to kill bacteria Prevents algae growth kills disease causing microorganisms |
|
Why is chlorine important for water treatment? |
it lowers death rates- less people die from water-bourne diseases. Over 1bn dont have access to clean water- very expensive. Chlorine increases life expectancy. V important. |
|
What are the disadvantages of chlorinating water? Why do people object? |
Chlorine reacts with compounds to form chlorinated hydrocarbons- carcinogenic. Chlorine gas irritates respiratory system. Liquid chlorine causes severe chemical burns. Some say we dont get a choice- forced 'mass medication' |
|
What are Alkalis? |
Type of chemical. A compound that forms hydroxide ions when dissolved in water. |
|
What is a neutralisation reaction? |
Acid and an alkali react to form a salt and water. The products are neutral. |
|
What are 2 types of neutralisation reactions? |
Acid+ Hydroxide= Salt + water Acid + Carbonate= Salt + water + carbon dioxide |
|
What are the uses of alkalis? |
Farmers use alkalis to neutralise acidic soils. Make chemicals for natural dyes. Convert fats and oils into soap. Manufacture glass. |
|
'History' of alkalis |
Used for hundreds of years. People relied on traditional sources- burnt wood & stale urine. 19th Century- Shortage |
|
The LeBlanc Process |
Alkalis had to be manufactured on a large scale. Process invented to make sodium carbonate. Sodium chloride mixed with sulfuric acid then heated with charcoal and limestone. |
|
Problems of the LeBlanc Process |
Very Polluting. Large volumes of acidic hydrogen chloride- damaged environment. A lot of solid waste. Released toxic Hydrogen Sulfide. Foul smell of rotten eggs. |
|
Products made using Chemistry |
Drugs, paints, dyes, used in industry, used in the home. agricultural chemicals, plastics, metals, fuels. So many chemicals- Cannot be tested thoroughly. Not enough data about risks. |
|
Problems with toxic chemicals |
Stay in environment if not broken down. End up in water ways/ eaten by animals. Spread over large area. Passed along food chains. Harm to animals, even humans |
|
How can pesticides be harmful? |
1) Insecticide seeps into river 2) small plants take it in 3)Tiny animals eat the plants 4) Small fish eats tiny animals 5) Eel eats small fish 6) Otter eats eels Toxic to creatures. |
|
How are plasticisers harmful? |
Leach out into water sources. Also toxic. |
|
Life Cycle Assessments- Stage 1 |
Choice of material: Water mostly needed. Metals mined and extracted. Lots of energy= pollution. Raw materials- No- renewable and finite. E.g: Crude oil: finite and causes lots of pollution. |
|
LCA- Stage 2 |
Manufacture: Lots of energy. Pollution: CO, HCl. How to dispose/ recycle. |
|
LCA - Stage 3 |
Using the product- can also damage environment. Paint; toxic fumes Burning; greenhouse gases Fertilisers; can leech out, damage ecosystem |
|
LCA- Stage 4 |
Product Disposal: Landfill site. Takes up space, pollutes. Might be incinerated(burnt); air pollution Some can be recycled- processed & re- used |