Combined Chemistry - 5.7 Flashcards

1
Q

What two elements make up a hydrocarbon?

A

Hydrogen and Carbon

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2
Q

What is crude oil a mixture of?

A

Hydrocarbons

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3
Q

The ancient remains of plankton and other marine organisms is the origin of what finite resource?

A

Crude oil

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4
Q

What is the general formula for a homologous series of alkanes?

A

CnH2n+2

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5
Q

Draw the structure of and write the formula for the following alkanes:

a) Methane
b) Ethane
c) Propane
d) Butane

A

a) Methane, CH4
b) Ethane, C2H6
c) Propane, C3H8
d) Butane, C4H10

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6
Q

What process is used to separate the hydrocarbons found in crude oil?

A

Fractional Distillation

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7
Q

Name three useful fuels obtained from crude oil.

A

Any three from:

  • petrol
  • diesel
  • kerosene
  • heavy fuel oil
  • liquefied petroleum gas
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8
Q

Name two useful materials that can be made from crude oil by the petrochemical industry.

A

Any two from:

  • solvents
  • lubricants
  • polymers
  • detergents.
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9
Q

Explain how fractional distillation of crude oil works.

A
  • Crude oil (a mixture of different length hydrocarbons) is heated.
  • Different length fractions have different boiling points. When heated, the fractions evaporate and rise up the tower.
  • The fractions cool down as they rise up the tower. When they reach their condensing point, they will condense, turn into a liquid and flow out of the tower.
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10
Q

What is the relationship between the length of a hydrocarbon and…

a) …boiling point
b) …viscosity
c) …flammability

A

a) The longer the hydrocarbon, the higher the boiling point (or vice versa)
b) The longer the hydrocarbon, the higher the viscosity (or vice versa)
c) The longer the hydrocarbon, the lower the flammability (or vice versa)

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11
Q

What type of reaction is shown by the equation below?

CH4 + 2O2 → CO2 + 2H2O

A

Combustion

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12
Q

What are the products of complete combustion of a hydrocarbon?

A

carbon dioxide (CO2) and water (H2O)

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13
Q

Write a balanced equation for the complete combustion of …

a) Propane
b) Ethane

A

C3H8 + 5O2 → 3CO2 + 4H2O

2C2H6 + 7O2 → 4CO2 + 6H2O

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14
Q

Describe the conditions needed for:

a) Catalytic cracking
b) Steam cracking

A

a) Catalyst (Aluminium oxide) and high temperature
b) Steam and high temperature

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15
Q

What are the products of cracking?

A

Alkanes and Alkenes

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16
Q

What is the test for an alkene?

A
  • Add bromine water
  • Turns from orange to colourless
17
Q

Which are more reactive? Alkanes or Alkenes?

A

Alkenes

18
Q

a) Complete the equation below:

C8H18 → C4H10 + _______

b) What process is shown by the equation above?

* This is just an example, you will have to complete any equation for this process.

A

a) C8H18 → C4H10 + C4H8
b) Cracking

19
Q

Why is cracking useful for modern life?

A
  • Alkenes (that are made from cracking) are used to make polymers
  • Alkenes (that are made from cracking) are used as the starting material for the production of many chemicals
  • Cracking produces short hydrocarbons that makes useful fuels