Carbon compounds as fuel and feedstock

Question 1

What is a hydrocarbon?

Answer 1

A molecule made up of only hydrogen and carbon atoms only

Question 2

What is the general formula for alkanes

alkAne

Answer 2

CnH2n+2

Question 3

Name the four different alkanes

Answer 3

Methane
Ethane
Propane
Butane

Question 4

How many carbon atoms in methane?

Answer 4

One

Question 5

How many carbon atoms in ethane

Answer 5

Two

Question 6

How many carbon atoms in propane?

Answer 6

Three

Question 7

How many carbon atoms in butane?

Answer 7

Four

Question 8

How many covalent bonds do carbon atoms ALWAYS make?

Answer 8

FOUR

Question 9

Scientists say that alkanes are saturated. What does this mean?

Answer 9

Saturated means that the carbon atoms are fully bonded to the hydrogen atoms with single convalent bonds

Question 10

What is crude oil

Answer 10

A non-renewable resource

Question 11

What is crude oil made out of?

Answer 11

Plankton fossilised from millions of years ago

Question 12

What type of covalent bonds are in alkanes?

Answer 12

Single covalent bonds

Question 13

How many covalent bonds do hydrogen atoms make in alkanes?

Answer 13

One

Question 14

Explain the process of fractional distillation

Answer 14

1. Crude Oil is heated to a very high temperature. This causes the crude oil to boil and the hydrocarbons evaporate and turn into gas
2. This gas is fed into a fractional distillation collumn. The collumn is hotter at the bottom and cooler at the top
3. The hydrocarbon vapours rise up the collumn and then condense into a liquid when they reach their boiling point.
   Long-chain hydrocarbons have very high boiling points and they condense at the bottom of the collumn. Short-chain hydrocarbons have very low boiling points and they continue to rise, then condense when they reach their boiling points.
4. The liquid fractions are then removed from the collumn

Question 15

How are the different fractions separated in fractional distillation

Answer 15

They are separated using their different boiling points

Question 16

Name two different fuels that are come from crude oil in fractional distillation

Answer 16

Diesel

Petrol

Question 17

What is diesel used for?

Answer 17

Fuel for lorries

Question 18

What is petrol used for?

Answer 18

Fuel for cars

Question 19

What is viscosity?

Answer 19

The thickness of a liquid

Question 20

What happens to the viscosity of hydrocarbons with increasing molecular size

Answer 20

Viscosity increases

Question 21

What is flammability?

Answer 21

How easily a hydrocarbon combusts

Question 22

What happens to the flammability of hydrocarbons with increasing molecular size

Answer 22

Flammability decreases

Question 23

Do long-chain hydrocarbons have high or low viscosity?

Answer 23

High viscosity

Question 24

Do short-chain hydrocarbons have high or low viscosity?

Answer 24

Low viscosity

Question 25

Do **long-chain hydrocarbons have high** or **low** to **flammabilty**

Answer 25

**Low flammability** | they are **hard** to **combust**

Question 26

Do **short-chain hydrocarbons** have **high** or **low flammability**?

Answer 26

**High flammability** | they are **easy** to **combust**

Question 27

**What happens** to the **boiling points** of **hydrocarbons** with **increasing molecular size**

Answer 27

The **boiling point increases**

Question 28

Do **long-chain hydrocarbons** have **high** or **low boiling points**?

Answer 28

**High boiling points**

Question 29

Do **short-chain hydrocarbons** have **high** or **low boiling points**?

Answer 29

**Low boiling points**

Question 30

The **combustion** of **hydrocarbons releases ___** | **fill in the blank**

Answer 30

The combustion of hydrocarbons releases **energy**

Question 31

**What** happens to the **carbon** and **hydrogen** in **hydrocarbons** when they are **combusted**?

Answer 31

The **carbon** and **oxygen** are **oxidised**

Question 32

**What** are the **products** of the **complete combustion** of **hydrocarbons**?

Answer 32

**Carbon dioxide** + **Water**

Question 33

**What** causes **combustion** to be **complete**

Answer 33

When there is an **excess** of **oxygen**

Question 34

**What** is the **complete combustion** of **hydrocarbons**?

Answer 34

When **hydrocarbons burn completely** in an **excess** of **oxygen** to produce **carbon dioxide** and **water**

Question 35

**What** is **incomplete combustion**

Answer 35

A **combustion reaction** in which **hydrocarbons** are not **completely burned** as there is not a **sufficient supply** of **oxygen**

Question 36

**What** are the **porducts** of **incomplete combustion**?

Answer 36

**carbon (soot)** + **carbon monoxide** + **water**

Question 37

**What** are the **tests** to find out the **presence** of **water** as a **product** of **complete combustion**?

Answer 37

**Anhydrous copper sulfate changes colour** from **white** to **blue** when **water** is **present** or **Cobalt chloride paper** changes colour from **blue** to **pink** when **water** is **present**

Question 38

**Why** is it **dangerous** for the **incomplete combustion** of **hydrocarbons** to **occur** in a **home setting**

Answer 38

**Incomplete combustion** of **hydrocarbons** produces **carbon monoxide**. This is a **toxic gas** which **binds** to **haemoglobin**in **blood** instead of **oxygen**