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Flashcards in C3 Deck (20):
1

What are the three m ost important raw materials in the earths crust?

Limestone

formed  when shellfishdied forming sediment on the sea floor

hardened to form limestone

sedimentary rock

movement of the tectonic plates pushes rock to the surface

rock eroded away showing limestone

Coal

-formed by ancient ferns were compressed without oxygen,leaving coal

Salt

-rivers bring dissolved salts into the sea

- climate change evaporated the water, leaving salt that mixed with sand, which was blown by the wind

rock salt formed and was buried under sediment

ripples in the rock indicate water was present

2

What the three methods of salt extraction?

1. Evaporation of sea water

can be evaporated under the Sun

leaves salt cyrstals

needs large area and may spread salt into the local habitat

2. Solution Mining

- water pumped in  the mine

salt dissolves to form a brine

brine transported away

-pure,yet can cause structural frailties to the land

3. Mining

-mining rock salt

- inefficient and lacks purity

much salt needs to be left in the mines as support

3

What is salt?

NaCl

sodium chloride

4

Why is salt used as grit?

As it lowers the freezing point of ice, making it melt

5

What is salt used for?

Flavouring

preserving food

prevents bacterial growth

used in chemical experiments

6

Why is too much salt bad for your health?

Salt may cause increased blood pressure and even heart attacks or strokes

 can be classified asa hazard

7

What is a neutralisation reaction/

alkali+acid=salt+ water

8

What are alkalis uesd for?

Dying clothes

Neutralising acidic soil

making soap and glass

9

What was the original alkalis?

stale urine and burnt ash

seaweed also, which was used to neutralise acidic soil

10

What was the first industrail alkali?

CaCo3

Made by heating lime in a kilm

Used when removing impurities from iron

making glass and neutralising soil

11

Who discovered how to make an alkali?

1787 frenchman Nicholas Leblanc

12

What was leblanc's process and what were some of the issues?

proces was to make sodium carbonate by reacting salt with limestone

gave off large amounts of hydrogen chloride(acidic gas) pollutant

also released hydogen sulfide

later hydrogen was converted into chlorine and hydorchloric acid

13

How can chlorine be produced from hydrogen chloride?

Reacting it with maganses oxide

oxidation converts hydrogen chloride into chlorine

14

What are some reactions involving acids?

Hydroxide+ acid produces salt and water

Carbonate+ acid produces salt+water+carbon dioxide

15

What are the riska and benefits of using clorine in drinking water?

Good

kills microogranisms

destroyed typhoid and cholera in water

saved lives

Bad

A toxic gas

used in wars

can react with organic materials to form toxic and catcinogenic compounds

positives outway the risks

16

What is electrolysis?

 This where an anode(positive electrode) and a cathode(negative electrode)

attract the free positive and negative ions iun the water

it can be used to make chlorine and hydrogen gas

 

17

What bare the uses of chlorine and hydrogen gas and sodium hydroxide?

-Chlorine for making plastics like PVC, medicine , crop protection

- hydrogen= margarins, rocket fuel, fuel cells

sodium hydroxide - used in paper recycling, industrial cleaners, refining aluminium

18

What are the environmental impacts of chlorine products

- chlorine in fridges and aerosals are non recyclable

linked to ozone depletion

chlorine in paper bleaching, releases dioxins- cancer risk

19

Is PVC dangerous?

 

plasticised PVC used in electrical wires 

-plasticiser molecules can be leached out and caused harmful effects

PVC toys banned in Europe and USA

-gives off dioxins when burnt- cancer risk

20

What is the Life Cycle Assesement?

measures energy used to make and dispose a substance and its environmental impacts

4 stages

1. How much natural resources are required?

2.How much energy is needed or produced?

3.How much water and air is used

4. how is the environment affected

requires lots of data

has limitations, cars can be disposed differently