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Further Additional Science > Chemistry > Flashcards

Chemistry Flashcards

1
Q

What are the alkali metals

A

The elements in group 1

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2
Q

What are the properties of alkali metals

A

Metals with low density (Li, Na and K are less dense than water)
React with water, releasing hydrogen
Form hydroxides that dissolve in water to give alkaline solution
React with non-metals to form ionic compounds (+1).The compounds are white solids that dissolve in water to form colourless solution

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3
Q

In Group 1, the further down the element is …

A

The more reactive the element

The lower its melting and boiling point

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4
Q

Compared to the alkali metals, transition elements:

A 
Have higher melting points (except Mercury)
Have higher densities
Are stronger and harder 
Less reactive
Do not act vigorously with water
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5
Q

What are halogens

A

Elements in group 7

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6
Q

What happens when halogens react with metals

A

The halide ion carries a charge of -1

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7
Q

In Group 7, the further down the group an element is:

A

The less reactive it is

The higher the melting point and boiling point

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8
Q

A more reactive halogen can displace a …

A

… less reactive halogen from an aqueous solution of its salt

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9
Q

Why can the trends in reactivity within groups in the periodic table be explained

A

The higher the energy level of the outer electrons, the more easily electrons are lost and the less easily electrons are gained

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10
Q

What is formed when soap reacts with soft water

A

Lather

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11
Q

What does hard water react with soap to form

A

Scum so more soap is needed to form a lather

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12
Q

What is a benefit of soap-less detergents

A

They do not form scum

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13
Q

What does hard water contain

A

Dissolved compounds, usually of calcium and magnesium. The compound dissolve when the water comes in contact with rock

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14
Q

What are the two types of hard water

A

Temporary hard water - softened by boiling

Permanent hard water - remains hard when boiled

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15
Q

What does temporary hard water contain

A

Hydrogencarbonate ions (HCO3)

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16
Q

What happen to Hydrogencarbonate ions when they decompose thermally

A

The produce carbonate ions which react with calcium and magnesium ions to form precipitate

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17
Q

Negative of permanent hard water

A

Increased costs because more soap is need to create a lather

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18
Q

Negative of temporarily hard water

A

When it is heated up, it can create lime scale which reduces the efficiency of heating systems and kettles

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19
Q

Benefit of hard water

A

Calcium compounds are good for the development and maintenance of good bones and teeth as well as helping reduce heart disease

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20
Q

How can permanently hard water be made soft

A

Removing the dissolved calcium and magnesium ions

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21
Q

How can permanently hard water be made soft by adding sodium carbonate

A

It reacts with the calcium and magnesium ions to form a precipitate of calcium carbonate and magnesium carbonate

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22
Q

How can permanently hard water be made soft by using commercial water softeners

A

Ion exchange columns contain hydrogen ions or sodium ions, which replace the calcium and magnesium ions when water passes through the column

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23
Q

What is water of the correct quality essential for

A

Life

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24
Q

What should drinking water for humans have

A

Sufficiently low levels of dissolved salts and microbes

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25
Q

What can water filters containing carbon, silver and ion exchange resins do

A

Remove some dissolved substances from tap water to improve the taste and quality

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26
Q

Why might chlorine be added to drinking water

A

To reduce microbes

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27
Q

Why might fluoride be added to drinking water

A

To improve dental health

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28
Q

How can pure water be obtained

A

Distillation which requires a large amount of energy and thus is very expensive

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29
Q

How is water of the correct quality produced

A

Choosing an appropriate source
Passing the water through filter beds to remove any solids
Sterilising with chlorine

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30
Q

What information is given from calorimetry

A

Relative amount of energy released when substances burn

Used to compare the energy released by foods and fuels

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31
Q

What is energy released in

A

Joules (J)

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32
Q

How can the energy released or absorbed by a chemical reaction in solution be calculated

A

The measured temperature change of the solution when the reagents are mixed in an insulated container

(Used for neutralisation reaction and reactions of solids and water)

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33
Q

During a chemical reaction:

A

Energy must be supplied to break bonds

Energy is released when bonds are formed

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34
Q

What happens in an exothermic reaction

A

The energy from forming new bonds is greater than the energy needed to break existing bonds

35
Q

What happens in an endothermic reaction

A

The energy to break existing bonds is greater than the energy released from forming new bonds

36
Q

What do catalysts provide

A

A different pathway for a chemical reaction that has a lower activation energy

37
Q

What can hydrogen be burned as

A

A fuel in combustion engines but they’re expensive

Hydrogen + oxygen -> water

38
Q

Where can hydrogen be used

A

In fuel cells that produce electricity to power vehicles

39
Q

What can the flame test be used to do

A

Identify metal ions

40
Q

What colour does lithium result in during the flame test

A

Crimson

41
Q

What colour does sodium compounds result in during the flame test

A

Yellow

42
Q

What colour does potassium result in during the flame test

A

Lilac

43
Q

What colour does calcium result in during the flame test

A

Red

44
Q

What colour does barium result in during the flame test

A

Green

45
Q

How do you test for aluminium, calcium and magnesium ions

A

They form white precipitates with sodium hydroxide but the aluminium hydroxide precipitate dissolves in excess sodium hydroxide solution

46
Q

How do you test for copper (II), iron (II) and iron (III)

A

Coloured precipitates with sodium hydroxide solution.

47
Q

What colour precipitate does copper (II) form with sodium hydroxide solution

A

Blue

48
Q

What colour precipitate does iron (II) form with sodium hydroxide solution

A

Green

49
Q

What colour precipitate does iron (III) form with sodium hydroxide solution

A

Brown

50
Q

What do carbonates react with dilute acids to form

A

Carbon dioxide

51
Q

How does carbon dioxide react with limewater

A

It forms a white precipitate. This turns lime water cloudy

52
Q

In the presence of dilute nitric acid, how do halide ions in solution react with silver nitrate solution

A

Precipitates are produced

53
Q

In the presence of dilute nitric acid, silver chloride reacts to silver nitrate solution to give what colour precipitate

A

White

54
Q

In the presence of dilute nitric acid, silver bromide reacts to silver nitrate solution to give what colour precipitate

A

Cream

55
Q

In the presence of dilute nitric acid, silver iodide reacts to silver nitrate solution to give what colour precipitate

A

Yellow

56
Q

In dilute hydrochloric acid, sulfate ions in solution reacts with barium chloride solution, to give what

A

A white precipitate

57
Q

What can you measure using titration

A

The volumes of acid and alkali solution that react with each other.

58
Q

If you know the concentration of one of the reactants, what can you figure out

A

The concentration of the other reactant using the results of the titration

59
Q

What are the raw materials in the Haber process

A

Nitrogen - from the air

Hydrogen - natural gas or other source

60
Q

How is the Haber process carried out

A

The purified gases are passed over a catalyst (iron)
At 450 degrees and a pressure of 200 atmospheres
Some hydrogen and nitrogen reacts to form ammonia
Some ammonia breaks down back into hydrogen and nitrogen
The ammonia liquefies when cooled and is removed
The unused reactants are recycled

61
Q

When is equilibrium reached, when a reversible reaction occurs in a closed system

A

When the reactions occur at exactly the same rate on each direction

62
Q

What depends on the conditions of the reaction

A

The relative amounts of all the reacting substances at equilibrium

63
Q

If the temperature is raised in a reversible reaction …

A

… The yield from the endothermic reaction increased and the yield from the exothermic reaction decreases

64
Q

If the temperature is lowered in a reversible equation…

A

… The yield from the endothermic reaction decreases and the yield from the exothermic reaction increases

65
Q

What happens when the pressure is increased in a gaseous reaction

A

The reaction that produces the least amount of molecules will be favoured (as shown by the equation)

66
Q

Which functional group do alcohols contain

A

-OH

67
Q

What are the first three members of a homologous series of alcohols

A

Methanol
Ethanol
Propanol

68
Q

Properties of methanol, ethanol and propanol

A

Dissolve in water to form a neutral solution
React with sodium to produce hydrogen
Burn in air
Are used as fuels and solvents
(Ethanol is the main alcohol in alcoholic drinks)

69
Q

How can ethanol be oxidised to ethanoic acid

A

Chemical oxidising agents

Microbial action

70
Q

Ethanoic acid is the main acid in which aqueous solution …

A

… Vinegar

71
Q

What is ethanoic acid a member of

A

Carboxylic acids

72
Q

Which functional group does carboxylic acids have

A

-COOH

73
Q

Properties of carboxylic acids

A

Dissolve in water to make acidic solutions
React with carbonates to produce carbon dioxide
React with the alcohols in the presence of an acid catalyst to produce esters
Do not ionise completely when dissolved in water and so are weak acids
Aqueous solution of weak acids have a higher pH value than aqueous solutions of a strong acid with the same concentration

74
Q

What is ethyl ethanoate

A

An ester produced by ethanoic acid and ethanol

75
Q

What is the functional group of esters

A

-COO

76
Q

Properties of esters

A

Volatile compounds with distinctive smells and are used as flavouring and perfumes

77
Q

What happens in water treatment works

A

Water passes through a mesh screen to remove large pieces
Chemicals added to make solids and microbes stick together and fall to the bottom
Water filtered through gravel beds to remove solids
Water is chlorinated to kill off any harmful microbes

78
Q

Equation for titration experiments

A

Number of moles = concentration * volume

CV of the alkali = CV of the acid

79
Q

Method of calorimetry

A

Put 50g of water in the copper can record its temperature
Weight the spirit burner and lid
Put the spirit burner underneath the can and light the wick. Heat the water, stirring constantly, until the temperature reaches approx. 50 degrees
Put out the flame using the burner lid, and measure the final temperature of the water
Weigh the spirit burner and lid again

80
Q

Fuel cells

A

An electrical cell that’s supplied with a fuel and oxygen and uses energy from the reaction between them to generate electricity

81
Q

Pros of fuel cells in the car industry

A

Doesn’t produce any conventional pollutants
Only by-product is water (helpful in cities with air pollution)
Could eventually help countries to become less dependent on crude oil

82
Q

Cons of fuel cells in the car industry

A

Hydrogen is a gas and takes a lot of storage space as opposed to liquids (petrol)
Hydrogen is very explosive and so hard to store safely
The hydrogen fuel is often made from hydrocarbons (fossil fuel) or by electrolysis of water (uses electricity)

83
Q

How to do titrations

A

Use pipette to put alkali in conical flask
Add indicator (phenolphthalein or methyl orange)
Pour acid in the burette until the meniscus is at 0
Do a rough titration to find an idea of acid needed
Record results of titration until you have 3 titres within 0.1 cm3 of each other

Further Additional Science (3 decks)

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