Gases In The Air Flashcards
(33 cards)
Write down the main components of air and their approximate percentages in the atmosphere Nitrogen Oxygen Carbon dioxide Argon Noble gases Water vapour
- 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;
Observations when sulfur burns (3)
Yellow, solid Sulfur melts to a red liquid
Burns with a blue flame
Colourless pungent Gas Sulfur dioxide
Why is nitrogen unreactive (inert) (2)
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
Uses of nitrogen (2)
Coolant (liquid) Food packaging (gas)
Physical properties of nitrogen (3)
- colourless, odourless gas
- neutral (pH 7)
- insoluble in Water
- Lack of reactivity due to its triple covalent bond
Diagram of ammonia
Nitrogen atom (5) (one lone pair) Bonded with 3 hydrogen atoms
Physical properties of ammonia (4)
- colourless gas
- characteristic pungent smell
- less dense than air
- very soluble in water
Describe the test for ammonia
- a glass rod dipped in concentrated hydrochloric acid will form white smoke of ammonium chloride as the only product
Give the symbol equation for the test for ammonia
HCl (g) + NH3(g) —> NH4Cl(s)
Equations for making fertiliser out of ammonia (2)
2NH3 + H2SO4 —> (NH4)2SO4
ammonia + sulfuric acid —> ammonium Sulfate
NH3 + HNO3 —> NH4NO3
Ammonia + nitric acid —> ammonia nitrate (100% atom economy)
Advantages of nitrogenous fertilisers (2)
- Greater nitrogen uptake by plant, producing larger, healthier plants
- Increase crop yield therefore increases profits
Disadvantages of nitrogenous fertilisers (2)
- 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
List the impacts of eutrophication caused by nitrogenous fertilisers (4)
- excess algae growth
- leads to death of algae
- microorganisms use oxygen to break down algae
- lack of oxygen in water kills fish
Testing for metal ions with Aqueous Ammonia;
Mg2+
Al3+
Zn2+
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]
Describe the laboratory preparation and collection of hydrogen using zinc (5)
- 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
Physical properties of hydrogen (4)
- Colourless, odourless gas
- less dense than air
- insoluble in water
- neutral
Uses of hydrogen (3)
- weather balloons
- hardening vegetable oils- makes margarine
- Potential clean fuel
Clean fuel
A clean fuel is one which when burned does not produce any toxic or polluting products
Benefits of hydrogen as a fuel
- clean burning fuel, only produces water therefore causes no pollution
- can be used safely in fuel cells
Drawbacks and risks of hydrogen as fuel (4)
- 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)
Describe the laboratory preparation and collection of oxygen by the catalytic decomposition of hydrogen peroxide
- 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
List the physical properties of oxygen (5)
- Gas
- Colourless
- Odourless
- Slightly soluble in water
- Neutral
Uses of oxygen
- Medicine ; breathing apparatus
- Welding
- Rocket fuel
Describe the reaction of oxygen with hydrogen, carbon, sulfur, magnesium, iron and copper and classify the products as acidic or basic (6)
- 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
