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GCSE Chemistry > 5) Separate Chemistry > Flashcards

5) Separate Chemistry Flashcards

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1
Q

Where are transition metals found?

A

In the middle of the periodic table

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2
Q

How does transition metal melting point compare to alkali metals?

A

Higher melting point

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3
Q

How does transition metal strength compare to alkali metals?

A

Stronger and harder

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4
Q

How does transition metal density compare to alkali metals?

A

Higher density

More mass for the same volume

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5
Q

How does transition metal reactivity compare to alkali metals?

A

Less reactive

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6
Q

What are special properties of transition metals?

A

Can form ions with diofferent positive charges
Can form different coloured compounds
Often used as catalysts

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7
Q

What transition metals are used at catalytic converters in cars?

A

Platinum

Rhodium

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8
Q

What is corrosion?

A

The gradual destruction of metals because of reactons with oxygen and water

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9
Q

What is the reaction of rusting?

A

Iron + oxygen + water –> hydrated

iron (III) oxide

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10
Q

What is the rusting experiment?

A

Place iron nail in boiling tube under conditions:
Only water - no rust
Only air - no rust
Air and water - rust

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11
Q

What are the 3 main ways of preventing corrosion?

A

Coatings
Galvanising
Sacrificial method

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12
Q

What is galvanising?

A

A hybrid of coatings and sacrifical method
Protected metal is sprayed with more reactive metal (coating)
If more reactive metal is damaged it protects as sacrifical metal

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13
Q

What are corrosion coatings?

A

Applying a barrier such as greasing, painting or electroplating

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14
Q

What is a disadvantge of coatings?

A

Any damage leads to metal becoming exposed

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15
Q

What is the sacrifical method of corrosion?

A

Metal requiring protection has more reactive metal atatched to it
Water and oxygen will stop reacting with protected metal

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16
Q

What process is used to electroplate objects?

A

Electrolysis

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17
Q

What is the process of electroplating?

A

Metal to be electroplated placed at cathode and coating metal at anode

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18
Q

Why do we electroplate?

A

To coat a cheaper metal with a more expensive one (jewellery)

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19
Q

What are alloys?

A

A combination of 2+ elements with at least 1 metal

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20
Q

Why are alloys stronger than pure metals?

A

Ions of different sizes cannot slide across each other easily

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21
Q

What are uses of aluminium alloys?

A

Armour plating

Manufacturing planes

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22
Q

What is bronze an alloy of?

A

Copper

Tin

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23
Q

What is bronze used for?

A

Making coins
Electrical hardware
Statues

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24
Q

How many carats is pure gold?

A

24 carats

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25
Why does gold often become an alloy?
Pure gold is soft
26
What is brass an alloy of?
Copper | Zinc
27
What is brass used for?
Hinges Locks Instruments
28
What is steel an alloy of?
Iron | Other metals
29
How do stainless steels react with oxygen and water?
They are strong and resistant to corrosion
30
What can the concentration of a solution be measured in?
Moles (mol/dm^3) | Mass (g/dm^3)
31
What do we need to know to calculate the amount of solute in a solution?
Concentration of solution | Volume of solution
32
What do we need to know to calculate the concentration of a solution?
Volumes of 2 solutions that react completely | Concentration of 1 of these solutions
33
What is a solute?
A dissolved substance
34
How is the concentration of a solution calculated?
Concentration of solution = amount of solute / volume
35
How many dm^3 does any 1 mole of gas take up in a room at room temperature and normal pressure?
24 dm^3
36
What 4 factors ensure percentage yield stays below 100%?
Incomplete reactions Waste Extraction Side reactions
37
How can an incomplete reaction happen?
Slow reaction isn't given enough time to happen | Reversible reaction has some products converted back to reactants
38
How can waste occur in reactions?
Some chemicals will remain stuck on apparatus
39
How can extraction reduce percentage yield?
Difficult to fully separate product from reaction mixture
40
How do side reactions reduce percentage yield?
Intended product is not created
41
What is the equation for percentage yield?
Percentage yield = real yield / theoretical yield x 100
42
What is the actual yield?
The mass of a desired product obtained from a reaction
43
What is the theoretical yield?
The maximum mass of a product that could possibly be created from a reaction
44
What can theoretical yield be calculated from?
Balanced equations if mass of reactants is known
45
What is percentage yield?
A comparison of the actual and theoretical yields of a reaction
46
What is the equation for atom economy?
atom economy (%) = relative molecular mass of desired products / total relative molecular mass of all reactants x 100
47
What is atom economy?
The amount of reactants that end up as useful products
48
Why are reaction pathways with high atom economies good?
Cost-effective | Low waste
49
What is the equation for moles?
Moles = mass / Mr
50
What is reacted in the Haber process?
Nitrogen | Hydrogen
51
What are the stages of the Haber process?
1) Collect and purify nitrogen and hydrogen gases 2) Pass over iron catalyst 3) Condensation 4) Recycling
52
What temperature and pressure are nitrogen and hydrogen passed over an iron catalyst in the Haber process?
450°C | 200 atm
53
What is the chemical symbol for ammonia?
NH3
54
What is the chemical equation for the Haber process?
N2 + 3H2 2NH3 (+heat)
55
How is the hydrogen used in the Haber process obtained?
Reacting methane in natural gas with steam
56
Is the forward reaction of the Haber process endothermic or exothermic?
Exothermic
57
How does increasing temperature affect the Haber process?
Increased rate of reaction | Decreased yield
58
Why is a catalyst used in the Haber process?
To establish equilibrium faster
59
How does increasing the pressure affect the equilibrium position of the Haber process?
Equilibrium moves towards products
60
What do fertilisers increase the number of?
Essential nutrients
61
What do fertilisers contain?
NPK salts
62
What 3 essential elements are added to soils in fertilisers?
Nitrogen Phosphorus Potassium
63
How is ammonium nitrate produced?
Reacting nitric acid and ammonia
64
What is the chemical equation for ammonium nitrate?
NH3 + HNO3 —> NH4NO3
65
Why is ammonium nitrate ideal in fertilisers?
It contains two sources of nitrogen
66
When are industrial reactions only possible?
If cost of making chemical needed is suitable
67
What must be considered in making chemical manufacturing feasible?
``` Catalyst use Cost of raw materials Danger of explosion Danger of fire Energy requirements ```
68
How is ammonium sulfate made?
``` Sulfuric acid (H2SO4) Ammonia (NH3) ```
69
How is ammonium sulfate produced through titration (laboratory method)?
1) Add drops of methyl orange to ammonia (turns yellow) 2) Slwoly add dilute sulfuric acid to ammonia until red (swirl flask) 3) Colour change (red) means you have ammonium sulfate
70
How do you purify the ammonium sulfate solution?
1) Repeat titration without using indicator using exact same volume of acid 2) Evaporate solution until only a small amount is left to get ammonium sulfate crystals 3) Once solution has crystallised, filter out crystals
71
Why does the industrial production of ammonium sulfate have several stages?
Ammonium and sulfuric acid must be made from their raw materials
72
What is one industrial method of producing ammonium sulfate?
Spray sulfuric acid into gas chamber where it reacts with ammonia to form ammonium sulfate powder
73
How can we make a simple cell?
Connect 2 different electrodes and put them in an electrolyte
74
What produces a voltage in a simple cell?
The difference in reactivity of the metals
75
How long does a chemical cell produce potential difference for?
Until the reactants are used up
76
What are advantages of fuel cells?
Reliable Compact and lightweight High efficiency Low pollution
77
How do fuel cells produce electrical energy?
Using a reaction between an external fuel source (hydrogen) and oxygen
78
What generates a voltage in hydrogen fuel cells?
The oxidation of hydrogen
79
What is the only waste product of hydrogen fuel cells?
Water
80
What is pumped in at the anode of hydrogen fuel cells?
Hydrogen
81
What is pumped in at the cathode of hydrogen fuel cells?
Oxygen
82
What is the anode half equation of hydrogen fuel cells?
2H2 —> 4H+ + 4e-
83
What forms at the cathode of hydrogen fuel cells?
Water
84
What is the cathode half equation of hydrogen fuel cells?
O2 + 4H+ + 4e- —> 2H2O
85
What is the overall equation of hydrogen fuel cells?
2H2 + O2 —> 2H2O
86
What is produced by hydrogen fuel cells?
Voltage | Water
87
Why are fuel cells better than rechargeable batteries?
Less toxic Indefinite lifetime Higher capacity Higher risks
88
Why are hydrogen fuel cells a safety risk?
Hydrogen and to be stored at high pressures | Hydrogen is explosive

GCSE Chemistry (10 decks)

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