Cody's Chemistry Blog: May 2011

Sunday, May 22, 2011

5.13 I can describe catayltic cracking of long-chain hydrocarbons

1. What is a catalyst?

A substance that speeds up the experiment

2. What is the purpose of the catalysts in the experiment?

To speed up the experiment

3. What is 'cracking' used for?

To break down long chain molecules into more shorter chain molecules

4. What are the common catalysts used in this process?

Silica or Aluminum etc.

5. What is the ceramic pot used for?

They are used as a catalyst to speed up the experiment

6. What is the purpose of cracking the Hydrocarbons?

The useful hydrocarbons tend to be the shorter ones, however, when we have a longer-chained one, they go to waste but we can use this process to break the long chained molecules into the shorter and useful molecules.

7. What gas Is produced from cracking paraffin?

Ethane

8.What do you have to look out for while carrying out the liquid paraffin experiment?

You have to very careful and avoid the water backfiring into the column or else an explosion will occur

5.12 I can recall the problems associated with the fractional distillation of crude oil

Read Chem4you P.145

a. When crude oil undergoes( fractional distillation )there are too many( long )chain hydrocarbons (e.g. bitumen) and produced not enough( short ) chain hydrocarbons (e.g.diesel)

b. To solve these problems,( long chain hydrocarbons) undergo a chemical reaction called (crackling)

5.11 I can recall how nitrogen oxides are formed in car engines

a) Write the general equation for the combustion of a fuel:

Combustion: Fuel + Oxygen (O₂) ---> Carbon Dioxide (CO₂) + Water (H₂O) + Energy

b) During combustion the nitrogen in air can react to form what gases?

Nitrogen Monoxide (NO) and Nitrogen Dioxide (NO₂)

c) What condition is necessary for this reaction to take place?

High temperatures

d) In what common object is this condition found?

Vehicles

e) Why is this condition needed for nitrogen to react?

In order to break the triple bonds of the Nitrogen molecules

f) What are the dangers of the products from this reaction?

Nitric Acid (HNO₃). This can cause acid rain

Saturday, May 14, 2011

5.10 I can recall the problems associated with incomplete combustion

1. What are the properties of carbon monoxide?

Colorless, Odorless, Poisonous

2. Explain how carbon monoxide is formed

Carbon monoxide is formed when the fuel gets burnt with insufficient oxygen. This is known as incomplete combustion.

3. Explain why carbon monoxide is poisonous

It is poisonous because the haemoglobin attaches CO (carbon monoxide)

CO (carbon monoxide) binds with haemoglobin much easier than O₂(Oxygen)and is irreversible. Thus, when a person takes in too much CO, the red blood cells can not provide enough oxygen for you, then you die because of asphyxiation (the condition being deprived with oxygen)

5.9 I can describe the trend in boiling point and viscosity of the main fracti

a. What is the trend in boiling point of the fractions?

As you go up the fractionating column, the boiling point decreases while the boiling point increases as you go down the column. The longer the chain, the larger the hydrocarbon, the higher the boiling point.

b. Define viscosity (source your definition)

(geonet.org.nz/volcano/glossary.html)- Ability of a liquid to flow

c. What is the trend in viscosity of the fractions?

The viscosity of the liquid increases as we go down the fractionating column

d. What is the trend in colour of the fractions?

As we go down the column, the color gets darker (see picture from right to left)

e. Why is crude oil separated into fractions?

Crude Oil alone is a useless,poisonous, viscose,black liquid. If we separated, we can have petrol oil,gasoline etc. which is more useful.

f. What process is used to separate crude oil into fractions?

Fractional Distillation

g. What physical property allows this process to work?

Different boiling point