CRUDE OIL AND FUELS

Question 1

How is crude oil made?

Answer 1

Remains of tiny, ancient sea animals and plants, mainly plankton, that were buried in mud. Over time, layer upon layer of rock was laid down on top, creating the conditions (high pressure and temperature, in the absence of oxygen) to make crude oil.

Question 2

What are alkanes?

Answer 2

Most of the hydrocarbons in crude oil are alkanes. Alkanes are saturated hydrocarbons. All the carbon-carbon bonds are single covalent bonds. This means they contain as many hydrogen atoms as possible in each molecule. No more hydrogen atoms can be added.

Question 3

What is the pattern in the formula of the alkanes?

Answer 3

CnH2n+2

Question 4

How does fractional distillation work?

Answer 4

Each hydrocarbon fraction contains molecules with similar numbers of carbon atoms. Each of these fractions boils at different temperatures because of their different sizes of molecules in it. Crude oil is hearted and fed in near the bottom of a tall tower (called a fractioning column) as hot vapour. The Colombo is kept hot and the bottom and cooler at the top. The gases move up the column and and the hydrocarbons condense when they reach the temperature of their boiling points. The different fractions are collected as liquids at different levels.

Question 5

What are the products of complete combustion (of a hydrocarbon)?

Answer 5

Carbon dioxide and water.

Question 6

How do you test for water?

Answer 6

Using blue cobalt water, it should turn pink if water is present.

Question 7

What happens when there is not enough air for a substance to burn in?

Answer 7

Incomplete combustion happens.

Question 8

What are the products of incomplete combustion?

Answer 8

Carbon monoxide gas and/or carbon along with water.

Question 9

Why use the cracking process?

Answer 9

To break up the heavier fractions that are not high in demand.

Question 10

How do you test whether a substance is an alkane or an alkene?

Answer 10

A positive test for an unsaturated hydrocarbon is that it turns orange bromine water colourless.

Question 11

What is crude oil?

Answer 11

Finite resource found in rocks
Formed over millions of years from the remains of Dead Sea animals and plants, mainly plankton
Mixture of many different carbon compounds
Most of the compounds are hydrocarbons (compounds containing carbon and hydrogen only)
Before it can be used, it must be speedster into fractions. This is done by fractional distillation.

Question 12

How does fractional distillation work?

Answer 12

Crude oil is heated so it turns into a mixture of gases
The gases enter a tall tower called a fractionating column
The column is very hot at the bottom and cooler at the top
Gases move up the column and condense when the temperature matches their boiling point
The different gases have different boiling points, so they condense and are collected at different places on the column.
Fractions with the smallest molecules have the lowest boiling points and are collected at the top of the column.

Question 13

As you go down the fractionating column what happens to the size of molecules?

Answer 13

Get bigger.

Question 14

As you go down the fractionating column what happens to the boiling point?

Answer 14

Increases.

Question 15

As you go down the fractionating column what happens to the volatility?

Answer 15

Decreases (less tendency to turn into a gas)

Question 16

As you go down the fractionating column what happens to the viscosity?

Answer 16

Increases (get thicker).

Question 17

As you go down the fractionating column what happens to the flammability?

Answer 17

Get less flammable (harder to set alight).

Question 18

What are the first four alkanes?

Answer 18

Methane, ethane, propane and butane.

Question 19

What are the bonds in alkanes?

Answer 19

Covalent.

Question 20

How many bonds to carbon atoms always have?

Answer 20

Four.

Question 21

How many bonds do hydrogen atoms always have?

Answer 21

One.

Question 22

Are alkanes saturated or unsaturated?

Answer 22

Saturated.

Question 23

What is the general formula for alkanes?

Answer 23

CnH2n+2

Question 24

What is cracking?

Answer 24

At high temperature, the atoms in an alkane molecule vibrate rapidly. If this temperature is high enough, the vibration becomes sufficiently vigorous for chemical bonds to break. This breakage of the C-C bonds in alkanes leads to the formation of smaller hydrocarbon fragments and is called cracking. The temperature required for cracking can be reduced by using a solid catalyst.

Question 25

What are alkanes?

Answer 25

Such as ethane are formed during the cracking of alkanes. The contains a carbon carbon double bond. Alkanes are unsaturated. We can test for an alkene using bromine water.