C9- crude oil and hydrocarbons ⛽️

Question 1

What is crude oil ?

Answer 1

• crude oil is a molecule of hydrocarbons, that was formed over millions of years, from the remains of ancient dead marine organisms.

Question 2

Where is crude oil found ?

Answer 2

• found in rocks, crude oil is a finite resource [meaning crude oil is used up at a faster rate, than it can be replaced]

Question 3

How is crude oil formed ?

Hint: remains

Answer 3

• crude oil is formed over millions of years, from the remains of tiny sea creatures called plankton- which were buried in mud

Question 4

What are hydrocarbons ?

Hint: molecules

Answer 4

• hydrocarbons, are molecules made up of hydrogen and carbon atoms only

Question 5

What’s an alkane ?

Answer 5

• an alkane, is a saturated hydrocarbon with the general formula CnH2n+2

Question 6

What’s the general formula of alkanes ?

Answer 6

• CnH2n+2
• [you have to multiply the number of carbon atoms by two, and then add two]

Question 7

How can the general formula of alkanes be used ?

Hint: multiply

Answer 7

• if the number of carbon atoms (n) is known, the number of hydrogen atoms can be calculated
• this is done, by multiplying the number of carbon atoms by 2 and then adding 2

Question 8

What is the structure of methane ?

Answer 8

• CH4 [methane has one carbon atom and four atoms of hydrogen]

Question 9

What is the structure of ethane ?

Answer 9

• C2 H6 [ethane has two carbon atoms, and six hydrogen atoms]

Question 10

What is the structure of propane ?

Answer 10

• C3 H8 [propane has three carbon atoms, and eight hydrogen atoms]

Question 11

What is the structure of butane ?

Answer 11

• C4 H10 [butane has four carbon atoms, and ten hydrogen atoms]

Question 12

What does it mean, that alkanes are saturated molecules ?

Hint: fully

Answer 12

• alkanes are saturated molecules because in alkanes, the carbon atoms are fully bonded to the hydrogen atoms

Question 13

What are examples where hydrocarbons, are used as fuels ?

Answer 13

• an example where hydrocarbons, are used as fuels are:
• ships, planes and cars

Question 14

What do hydrocarbons do, when they combust ?

Answer 14

• hydrocarbon fuels, release energy when combusted [burned].

Question 15

What happens during the combustion of hydrocarbons ?

Hint: OIL RIG

Answer 15

• during combustion, the carbon and hydrogen atoms in the fuel will react with oxygen as become oxidised [the loss of electrons; the gain of oxygen]

Question 16

What products are formed, during complete combustion of a hydrocarbon ?

Hint: unlimited

Answer 16

• if the oxygen that the carbon and hydrogen atoms react with are unlimited, this reaction produces carbon dioxide and water.
• this is because, the hydrocarbons completely combust

Question 17

What are the three key properties of hydrocarbons ?

Answer 17

• viscosity- meaning the thickness of a fluid
• flammability- meaning, how easily a hydrocarbon combusts [burns]
• and, boiling points- the temperature at which a liquid turns to a gas

Question 18

What is viscosity ?

Answer 18

• viscosity, is the thickness of a fluid. [the resistance of a fluid to flow]
• fluids with a high viscosity will flow slowly
• ; as the size of the hydrocarbon molecules increase, the molecules get more viscous.

Question 19

Fill in the gaps: because hydrocarbon molecules get more _______, if the size of hydrocarbon molecules increase, ____ chain hydrocarbons such as butane are extremely viscous.

Answer 19

• because hydrocarbon molecules get more viscous, if the size of hydrocarbon molecules increase, long chain hydrocarbons such as butane are extremely viscous.

Question 20

What are the flammability of hydrocarbons ?

Answer 20

• short-chain hydrocarbons such as methane are extremely flammable
• this is because, as the size of the hydrocarbon molecules increases, the molecules get less flammable
• ; long chain hydrocarbons such as butane, are very difficult to burn.

Question 21

What are the boiling points of hydrocarbons ?

Answer 21

• as the size of the hydrocarbon molecules increases, the boiling point also increases
• this means, very long chain hydrocarbons such as butane, have very high boiling points

Question 22

Why does the boiling point of hydrocarbons increase if the size of the hydrocarbon molecules increase ?

Hint: atoms and electrons

Answer 22

• because, the intermolecular forces bewteen alkanes become more significant, as the number of atoms and electrons in a molecule increase