//c/3/./3// Flashcards

1
Q
  1. What were alkalis used for even before industrialisation?
A
  • to neutralise acid soils
  • to make chemicals that bind natural dyes to cloth
  • to convert fats and oils into soap
  • to manufacture glass
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2
Q
  1. What are some traditional sources of alkali?
A
  • burnt wood

- stale urine

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3
Q
  1. What is it called when you react an acid and an alkali?
A

-neutralisation

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4
Q
  1. What is formed when you react an acid and an alkali together (neutralisation reaction)?
A

-salt and water

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5
Q
  1. What is an alkali (definition)?
A

-an alkali is a compound that forms hydrogen ions (OH-) when dissolved in water

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6
Q
  1. What is an example of an alkali?
A

Soluble hydroxides and carbonates are alkalis

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7
Q
  1. What does the reaction between an acid and a hydroxide give?
A

-salt and water

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8
Q
  1. What does the reaction between an acid and a carbonate give?
A

-salt and water and carbon dioxide

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9
Q
  1. What occurred in the nineteenth century regarding alkali?
A

Increased industrialisation led to a shortage of alkali in the nineteenth century

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10
Q
  1. What did increased industrialisation leading to a shortage of alkali in the nineteenth century mean?
A

Alkali had to be manufactured

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11
Q
  1. What was the first process for manufacturing alkali (sodium carbonate)?
A

-alkali was manufactured from salt (sodium chloride) and limestone (calcium carbonate) using coal as a fuel

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12
Q
  1. What did the first process of producing alkali from salt and limestone using coal as a fuel produce?
A

-it cased pollution by releasing large volumes of an acid gas (hydrogen chloride)
-it created heaps of solid waste that slowly released a toxic and foul smelling gas (hydrogen
sulfide)

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13
Q
  1. How can pollution problems sometimes be solved?
A

-by turning wastes into useful chemicals

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14
Q
  1. How is chlorine formed?
A
  • the oxidisation of hydrogen chloride

- electrolysing brine

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15
Q
  1. What is the symbol equation for the oxidation of hydrogen chloride to form chlorine?
A

4HCL+O2→2CL2+2H20

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16
Q
  1. What are the properties of a compound like compared to the properties of the elements from which it is made?
A

-the properties of a compound are completely different from the elements from which it is made

17
Q
  1. What is chlorine used to do?
A

-chlorine is used to kill microorganisms in domestic water supplies and as a bleach

18
Q
  1. What effect did the introduction of chlorination to treat drinking water make on public health?
A

-it had a major contribution

19
Q
  1. What are the effects of polluted water on health?
A

-can cause water borne diseases like cholera, typhoid and dysentery

20
Q
  1. What is the impact of water treatment with chlorine to control disease?
A
  • increases life expectancy

- reduces deaths by water borne diseases

21
Q
  1. What disadvantages are there to chlorinating water?
A
  • drinking water: chlorine reacts with organic compounds in water to form chlorinated hydrocarbons which may be cancer causing
  • making chlorine to chlorinate water: chlorine gas irritates respiratory system. Liquid chlorine can cause chemical burns. Accidents with either could be fatal
22
Q
  1. What is electrolysis?
A

-electrolysis is when an electric current can be used to bring about chemical change and make new chemicals

23
Q
  1. How is chlorine now obtained? (explain)
A
  • through electrolysis
  • electrolyse a salt solution (brine) by passing an electric current through it
  • this causes a chemical change, splitting the solution into hydrogen, chlorine, and sodium hydroxide
24
Q
  1. What products are made from the electrolysis of brine?
A

-sodium hydroxide, chlorine and hydrogen

25
Q
  1. What are important uses for chlorine which is extracted from the electrolysis of brine? 6
A
  • disinfectants
  • insecticides
  • plastics (PVC)
  • killing bacteria in water supplies
  • household bleach
  • hydrochloric acid (HCl)
26
Q
  1. What are important uses for hydrogen which is extracted from the electrolysis of brine?
A
  • used to make ammonia
  • change oils into fats to make margarine
  • for welding/metal cutting
27
Q
  1. What are important uses for sodium hydroxide which is extracted from the electrolysis of brine?
A
  • soap
  • ceramics
  • organic chemicals
  • paper pulp
  • oven cleaner
  • household bleach
28
Q
  1. What environmental impact does large scale electrolysis of brine have?
A
  • needs lots of energy= burns fossil fuels= releases CO2/ uses up finite resources
  • toxic mercury used in the process= can contaminate rivers= fisheries close/ people who ate fish became ill
  • toxic asbestos used in process= lung cancer
29
Q

What is sodium hydroxide?

A

-a strong alkali