Topic 8 Flashcards
8.1
What is a hydrocarbon?
-Compound
-ONLY…
-C & H₂ atoms
8.2
What is crude oil?
-Complex mixture of hydrocarbons (C atoms = in chains/rings)
-Finite resource
-Important source for useful substances e.g. fuels for vehicles, aircraft, ships, power stations; feedstock (raw materials) for petrochemical industry
8.2
Describe the formation of crude oil
-Sea animals die -> fall into sea bed (don’t decay)
-Sand + mud (sediment) form on top
-↑ pressure + temp turns them into crude oil
-Takes millions of yrs
8.2
Hydrocarbons can be arranged in chains and rings. Why?
-Each C atom forms 4 cov bonds
-C can be arranged in diff ways
8.3
Why does crude oil need to be separated?
Useless
8.3
Explain the process of separating crude oil into more useful mixtures
-Fractional distillation
-Heat oil -> liquid (w/ lowest bp) evaporates
-Gas enters column & reaches top -> cools & condenses -> collected as liquid
-Liquid w/ highest bp doesn’t condense
8.4
Name the compounds formed from the separation of crude oil starting with the coolest
-LPG (liquid petroleum gas)
-Petrol
-Kerosene
-Diesel
-Fuel oil
-Bitumen
8.4
State a use of LPG
Domestic heating & cooking
8.4
State a use of petrol
Fuel for cars
8.4
State a use of kerosene
Fuel for aircrafts
8.4
State a use of diesel
Fuel for trains & some other vehicles
8.4
State 2 uses of fuel oil
-Fuel for large ships
-Power stations
8.4
State a use of bitumen
Surface roads & roofs
8.5
Define the term ignition
Setting something on fire
8.5
Define the term viscosity
How thick/runny substance is (↑ viscosity = does NOT flow easily)
8.5
Compare the compounds in crude oil fractions
Top
-Small molec (less H & C atoms)
-↓ bp
-Ignite easily
-↓ viscosity
Bottom
-Large molec
-↑ bp
-Don’t ignite easily
-↑ viscosity
Darker as go down
8.6
What are alkanes?
-CnH2n+2
-Homologous series of hydrocarbons w/ single cov bond
-Saturated (means single bond)
8.6
What are alkenes?
-CnH2n
-Homologous series of hydrocarbons w/ C to C double cov bond
-Unsaturated
(Note: can only have 1 double bond)
8.6
What is the homologous series?
Series of compounds
-Same general formula
-Molecular formula of neighbouring compounds differ by CH2
-Gradual variation in physical properites
-Similar chemical properties
(Note: Top 2 = top ans)
8.6
What is a saturated hydrocarbon? [3 marks]
-Single cov bond
-ONLY
-H & C atoms
8.6
What are most of the compounds in crude oil?
Alkanes
8.6
Why is there no methene?
-Only 1 C atom
-No C to C double bond
8.6
Propane and propene are bubbled through separate samples of bromine water. Describe what would happen to the bromine water
-Bromine = yellow/orange
-(when added to) Propane: Stays same
-Propene: decolourises from orange -> colourless
8.7
Define the term combustion
Process of burning something
8.7
Describe the complete combustion of hydrocarbon fuels. State the equation
-Products = Co₂ + water
-E given out
Hydrocarbon + oxygen -> carbon dioxide + water
8.7
Why does the Bunsen burner have a blue flame when the air hole is open?
Lot of O₂ present
8.8
a) When does incomplete combustion of hydrocarbons occur? b) What are the products?
a) Limited supply of O₂
b) Water, C (soot), CO, CO₂
8.8
Explain why the incomplete combustion of hydrocarbons produces carbon and carbon monoxide
Not enough O₂ to turn C into CO₂
8.9
Explain how carbon monoxide behaves as a toxic gas
-Colourless, odourless, toxic gas
-Haemoglobin prefers to pick up CO
-Not enough O₂ for respiration
-Death
8.10
State 2 effects of soot (carbon)
-Dirty walls
-Aggravate respiratory problems
8.11
Explain 2 ways acid rain is formed
-Burn fuel -> sulfur impurities react w/ O₂ -> sulfur dioxide
-Dissolves in rain water -> sulfuric acid (acid rain)
-Car engines -> nitrogen reacts w/ O₂ -> nitrogen dioxide
-Dissolves in rain water -> nitric acid (acid rain)
8.12
State 3 effects of acid rain
-Kill fish
-Kill trees
-Damage buildings
8.13
Explain why oxygen and nitrogen react to produce oxides of nitrogen in car engines (internal combustion engines)
-Fuel mixes w/ air & ignited in engine ->↑ temp
-O₂ + N collide more -> react
8.14
