C4h-Purifying and testing water Flashcards Preview

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Flashcards in C4h-Purifying and testing water Deck (22)
1

What are the different types of water resources found in the UK?

Lakes
Rivers
Aquifers
Reservoirs

2

Why is water an important resource for many important industrial chemical processes?

It is a cheap raw material, a coolant and a solvent

3

Why is it important to conserve water?

All these resources are limited and demand for water increases every year

4

What are some pollutants that may be found in domestic water supplies?

Nitrate residues
Lead compounds
Pesticide residues

5

Why might water contain nitrates?

From excess fertiliser 'run off' into rivers and lakes

6

Why might water contain lead compounds?

From old lead pipes

7

Why might water contain pesticide residues?

From spraying too near rivers and lakes

8

What are the substances present in water before its purified?

Dissolved salts and minerals
Microbes
Pollutants
Insoluble materials

9

What are the key steps in water purification?

Filtration
Sedimentaion
Chlorination

10

What happens in filtration?

A wire mesh screens out large twigs then gravel and sand beds filter out solid bits

11

What happens in sedimentation?

Iron sulfate or aluminium sulfate is added to the water which makes fine particles clump together and settle at the bottom

12

Why are some soluble substances not removed from water during purification?

They cant be filtered out

13

What is the disadvantage of using sea water to make large quantaties of fresh water?

It is really expensive as distillation needs lots of energy

14

What solution is used to test for sulfate ions?

Barium chloride solution

15

What kind of precipitate do sulfate ions give?

White precipitate

16

What solution is used to test for halide ions?

Silver nitrate solution

17

What colour precipitate do choride ions give?

White precipitate

18

What colour precipitate do bromide ions give?

Cream precipitate

19

What colour precipitate do iodide ions give?

A pale yellow precipitate

20

What is the symbol equation for the reaction between silver nitrate and sodium chloride?

AgNO3 + NaCl --> AgCl + NaNO3

21

What is the symbol equation for the reaction between silver nitrate and sodium bromide?

AgNO3 + NaBr --> AgBr + NaNO3

22

What is the symbol equation for the reaction between silver nitrate and sodium iodide?

AgNO3 + NaI --> Agl + NaNO3