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Y12 Chem > Gases In The Air > Flashcards

Gases In The Air Flashcards

1
Q 
Write down the main components of air and their approximate percentages in the atmosphere 
Nitrogen 
Oxygen
Carbon dioxide 
Argon
Noble gases 
Water vapour
A 
- about 78% nitrogen;
• about 21% oxygen;
• about 0.03–0.04% carbon dioxide;
• about 1% argon;
• small proportions of other noble gases; and • varying proportions of water vapour;
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2
Q

Observations when sulfur burns (3)

A

Yellow, solid Sulfur melts to a red liquid
Burns with a blue flame
Colourless pungent Gas Sulfur dioxide

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3
Q

Why is nitrogen unreactive (inert) (2)

A

Due to the strong triple covalent bond in the diatomic molecule
A lot of energy is required to break this bond before the nitrogen atoms could react

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4
Q

Uses of nitrogen (2)

A 
Coolant (liquid)
Food packaging (gas)
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5
Q

Physical properties of nitrogen (3)

A
  • colourless, odourless gas
  • neutral (pH 7)
  • insoluble in Water
  • Lack of reactivity due to its triple covalent bond
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6
Q

Diagram of ammonia

A 
Nitrogen atom (5) (one lone pair)
Bonded with 3 hydrogen atoms
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7
Q

Physical properties of ammonia (4)

A
  • colourless gas
  • characteristic pungent smell
  • less dense than air
  • very soluble in water
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8
Q

Describe the test for ammonia

A
  • a glass rod dipped in concentrated hydrochloric acid will form white smoke of ammonium chloride as the only product
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9
Q

Give the symbol equation for the test for ammonia

A

HCl (g) + NH3(g) —> NH4Cl(s)

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10
Q

Equations for making fertiliser out of ammonia (2)

A

2NH3 + H2SO4 —> (NH4)2SO4
ammonia + sulfuric acid —> ammonium Sulfate
NH3 + HNO3 —> NH4NO3
Ammonia + nitric acid —> ammonia nitrate (100% atom economy)

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11
Q

Advantages of nitrogenous fertilisers (2)

A
  • Greater nitrogen uptake by plant, producing larger, healthier plants
  • Increase crop yield therefore increases profits
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12
Q

Disadvantages of nitrogenous fertilisers (2)

A
  • if fertiliser gets into rivers then it contributes to eutrophication
  • If gets into drinking water then can cause stomach cancer and condition in infants known as ‘blue baby’ syndrome
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13
Q

List the impacts of eutrophication caused by nitrogenous fertilisers (4)

A
  • excess algae growth
  • leads to death of algae
  • microorganisms use oxygen to break down algae
  • lack of oxygen in water kills fish
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14
Q

Testing for metal ions with Aqueous Ammonia;
Mg2+
Al3+
Zn2+

A 
Mg2+ 
colour of precipitate: white 
Solubility in excess NH4OH: no 
Ionic equation: Mg2+ + 2OH- —> Mg(OH)2
[insoluble in both reagants]
Al3+ 
colour of precipitate: white 
Solubility in excess NH4OH: no 
Ionic equation: Al3+ + 3OH- —> Al(OH)3
[will not dissolve in excess with ammonia]
Zn2+ 
colour of precipitate: white 
Solubility in excess NH4OH: yes, colourless solution 
Ionic equation: Zn2+ + 2OH- —> Zn(OH)2
[soluble in excess in both reagents]
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15
Q

Describe the laboratory preparation and collection of hydrogen using zinc (5)

A
  • Zinc metal and hydrochloric acid in conical flask
  • thistle funnel in conical flask (to add hydrochloric acid)
  • collect hydrogen through delivery tube
  • gas goes into beehive shelf in water trough
  • Gas travels up into gas jar
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16
Q

Physical properties of hydrogen (4)

A
  • Colourless, odourless gas
  • less dense than air
  • insoluble in water
  • neutral
17
Q

Uses of hydrogen (3)

A
  • weather balloons
  • hardening vegetable oils- makes margarine
  • Potential clean fuel
18
Q

Clean fuel

A

A clean fuel is one which when burned does not produce any toxic or polluting products

19
Q

Benefits of hydrogen as a fuel

A
  • clean burning fuel, only produces water therefore causes no pollution
  • can be used safely in fuel cells
20
Q

Drawbacks and risks of hydrogen as fuel (4)

A
  • hydrogen must be manufactured as it doesn’t occur naturally in large quantities
  • difficult to transport and store (extremely flammable gas and leaks are hard to detect as it is colourless, odourless)
  • Hydrogen used in fuel cells must be liquefied and stored under pressure in the vehicles which is expensive
  • Methods of hydrogen production for fuel cells can be highly polluting (burning methane releases CO2 a greenhouse gas)
21
Q

Describe the laboratory preparation and collection of oxygen by the catalytic decomposition of hydrogen peroxide

A
  • Calcium carbonate and hydrogen solid in hydrogen peroxide liquid in a conical flask
  • thistle funnel to add manganese (IV) oxide
  • reacts to form carbon dioxide through delivery tube into gas jar in the water trough
22
Q

List the physical properties of oxygen (5)

A
  • Gas
  • Colourless
  • Odourless
  • Slightly soluble in water
  • Neutral
23
Q

Uses of oxygen

A
  • Medicine ; breathing apparatus
  • Welding
  • Rocket fuel
24
Q

Describe the reaction of oxygen with hydrogen, carbon, sulfur, magnesium, iron and copper and classify the products as acidic or basic (6)

A 
- Hydrogen - 2H2 + O2 —> 2H2O
A combustion reaction 
- carbon ; C + O2 —> CO2 
Acidic gas. Dissolved in water to form a weakly acidic solution of carbonic acid 
Carbon monoxide is an exception. It is a non-metal oxide neutral gas 
- Sulfur ; S(s) + O2(g) —> SO2 (g)
Acidic non-metal oxide 
- Magnesium ; 2Mg(s) + O2 (g) —> 2MgO (s)
Basic metal oxide 
- Iron ; 3Fe + 2O2 —> Fe3O4
Basic metal oxide 
- Copper ; 2Cu + O2 —> 2CuO
basic metal oxide
25
Q

Describe the laboratory preparation and collection of carbon dioxide gas using calcium carbonate and hydrochloric acid (3)

A
  • Calcium carbonate solid in hydrochloric acid in conical flask
  • Carbon dioxide travels through delivery tube into beehive shelf in water trough
  • Bubbles of CO2 seen in gas jar
26
Q

Observation of carbon dioxide reaction with calcium hydroxide solution

A

When bubbled into limewater the carbon dioxide causes the limewater to change from colourless to milky white

27
Q

Excess CO2 reaction

A

When carbon dioxide, calcium carbonate and water react together the milky white suspension changes back to a colourless solution

28
Q

Uses of carbon dioxide (3)

A
  • fire extinguisher
  • in carbonated drinks
  • dry ice
29
Q

Physical properties of carbon dioxide (5)

A
  • colourless
  • odourless
  • Heavier than air
  • slightly soluble in water
  • acidic gas
30
Q

Show the symbol equation for the chemical reaction of carbon dioxide with water

A

CO2 + H2O —> H2CO3 weak carbonic acid

31
Q

Preparation of carbon dioxide symbol equation

A

CaCO3 + 2HCl —> CaCl2 + CO2 + H2O

Carbon dioxide is prepared from calcium carbonate marble chips and hydrochloric acid

32
Q

Test for carbon dioxide common name and chemical name

A

Limewater, Ca(OH)2 calcium hydroxide

33
Q

Test for hydrogen

A

Apply a lit splint

Burns with a squeaky pop

Y12 Chem (16 decks)

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