Wednesday, August 31, 2011

Advantages and disadvantages of preparing alcohol


Advantages
Disadvantages
Fermentation
-Cheap renewable resource (e.g sugar canes)
-It’s a very slow reaction, so it takes too much time
Industrially
-very fast and efficient
-also a continuous process
-Uses non-renewable resources like crude oil

Tuesday, June 21, 2011

3.6 and 3.7 i can recall the general formula and displayed formula of alkenes

Name of alkene
Molecular formula
Dot and cross diagram
Displayed formula
State at room temp (25oC)















































What is the general formula for alkenes?
1.       Describe and explain the trend in boiling point
The boiling points are lower because unsaturated alkenes have weaker bonds. 
2.       Explain why there is no such compound as methane
 because there is only one carbon in the equivalent alkane and so no carbon carbon double bond can be formed.
3.       How do you quickly identify from the displayed formula that the hydrocarbon is unsaturated?
unsaturated hydrocarbons have a display formula of: CnH2n,, saturated hydrocarbons have twice the amount plus two of hydrogens from carbons 

3.8 I can describe the reaction between alkenes and bromine

1.       Write the word equation showing the reaction between ethene and bromine water

2.       Draw the displayed formula of the reaction above
Take a photo of the answers to 1. and 2. and upload to your blog

3.       Explain the observations

4.       Why does this reaction not need a catalyst?

5.       What type of reaction is this called?

6.       Explain why this reaction is useful

3.5 I can recall the reaction of methane and bromine

Alkanes react with liquid bromine in the presence of UV


Explain why this condition is necessary
Energy is needed for bromine to break. The UV lights tickle the bromine, causing them to gain more energy and eventually breaking them
What is this type of reaction called?
Substitute reaction
State and explain the observation
Liquid bromine changes color from brown/red to colorless. This is because the bromine turns into bromine radacles after they break apart.. Hydrogen bromide is colorless
Draw the displayed formula of the reaction between methane and bromine 


Write out a balanced (with state symbols) the reaction between ethane and chlorine
CL2(L) --> C2H5Cl+ HCL
State and explain the observation in this chemical reaction
Ethane goes from yellow green to colorless.

Friday, May 27, 2011

3.5I can recall the reaction of methane and bromine

·         Alkanes react with bromine in the presence of UV
·         Explain why this condition is necessary
This condition is needed because the heat energy breaks the bonds
3.       What is this type of reaction called
Substitution reaction
4.       State and explain the observations
Changes color from brown to colorless
5.       Draw the displayed formula of the reaction between methane and bromine (upload a photo)

6.       Write out a balanced (with state symbols) the reaction between ethane and chlorine
C2H6( + Cl2(g) -->
7.       State and explain the observations in this chemical reaction

3.4 I can recall the products of complete and incomplete combustion of alkenes

1.       Saturated hydrocarbons are called Alkanes
2.       Small chain alkanes are used as fuels
3.       The reaction is called combustion
4.       The word equation for  this chemical reaction is :
fuel (Hydrocarbon) + Oxygen Carbon Dioxide +Water + ENERGY (heat, light, sound)
5.       If there is insufficient oxygen then the word equation is:
fuel (Hydrocarbon) +Oxygen Carbon monoxide + Water + ENERGY (heat, light, sound)
6.       The problem with this reaction is that Carbon monoxide is produced. This gas is a danger to the human body (see objective 5.11)
7.       Where can you find incomplete combustion?
          In cars
8.       What is used to reduce the harmful products from incomplete combustion?
         A catalytic converter
9.       During incomplete combustion a smoky flame is often seen, explain this observation
         It's because of the soot (unburned carbon)
Extension- Write a balanced equation for the combustion of propane gas
C3H8 (g) + 5O2 (g) --> 3CO2 (g) + 4H2O (l)
10. Describe the two chemical tests for water      
 anhydrous copper sulphate turns from white to blue
      

 cobalt 2 chloride paper turns from blue to pink



3.1 I can explain the terms homologous series, hydrocarbon, saturated, unsaturated, general formula and isomerism





Term
Definition
Example
Homologous series
 In chemistry, a homologous series is a series of organic compounds with a similar general formula.

 All the Alkanes.
Hydrocarbon
an organic compound containing only carbon and hydrogen.

 Methane
Saturated hydrocarbon
A hydrocarbon that has only single bonds between each carbon atom

 all the Alkanes
Unsaturated hydrocarbon
Unsaturated hydrocarbons are hydrocarbons that have double or triple covalent bonds between adjacent carbon atoms

 all the Alkenes
General formula
 Mathematical formula to show the ratio of one element to another

 CnH2n+2
Isomerism
In chemistry, isomers are compounds with the same molecular formula but different structural formulas

 2, Methylbutane

Tuesday, May 17, 2011

5.13 I can describe catalytic cracking of long-chain hydrocarbons

Define Catalyst
A substance that increases the rate of a chemical reaction
Why is catalyst used?
To increase the rate of chemical reaction
Why are high temperatures needed?
1) To obtain the energy needed to separate the long chain hydrocarbon
2) To also increase the rate of chemical reaction

Questions 
What are the conditions needed for catalyst cracking?
High temperatures
What does cracking do?
It converts long chain alkanes into into short chain alkenes
Would you want to remove the heat from the experiment? why?
No, because the gas contracts






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

When crude oil undergoes fractional distillation, there are too many long chain hydrocarbons ( eg. refianary gas) produced and not enough short chain hydrocarbons (eg. petrol). To solve these problems the long chain hydrocarbons undergo a chemical reaction called cracking

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


a.       Write the general equation for the combustion of a fuel
Fuel + O2 -----> Energy + CO2 + H2O
b.      During combustion the nitrogen in air can react to form what gases?
NOx (nitrogen and oxygen)
c.       What condition is necessary for the formation of these gases?
A high temperature
d.      In what common object is this condition found?
In cars/ Vehicles
e.      Why is this condition needed for nitrogen to react?
 because Nitrogen has very strong triple covalent bonds
f.        What are the dangers of the products from this reaction?
It can shorten your life by up to 9 years, due to lung disease, skin irritation, and cancers

Thursday, May 12, 2011

5.10 I can recall the problems associated with incomplete combustion

Properties of Carbon monoxide
It's highly toxic, odorless, and colorless
Explain how carbon monoxide is formed
In regular combustion: fuel + O2 --> CO2 + energy OR fuel + oxygen
but when there is lack of oxygen: fuel + O --> CO + energy
So basically, carbon monoxide forms when there is a lack of oxygen
Why is carbon monoxide poisonous?
Our hemoglobins have a liking for carbon monoxide, so instead of carrying oxygen, it carries carbon monoxide. This causes a lack of oxygen being delivered in our body, which can cause severe illness and eventually, death

Tuesday, May 10, 2011

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

What is the trend in boiling point of the fractions?
With each new fraction, their boiling point of the fractions increase
Define viscosity
Viscosity is the thickness of a liquid
What is the trend in viscosity of the fractions?
With each new fraction, they become more viscous
What is the trend in color of the fractions?
With each new fraction, their color becomes darker
Why is crude oil separated into fractions?
Because when separated, we can obtain more fossil fuels. Plus, crude oil that alone is useless.

What physical features allow this?
The difference in boiling points 

5.8: I can recall the names and uses of the main fractions obtained from crude oil

Description: Machine generated alternative text: Cut out the fractionating column below and stick it in your book.
5petroleum gases
‘iubricating oil’
‘. bitumen
- petrol -
ure
A fractionating column
I ______________
ZD
ZEEZZ
crude oil
vapour
Now cut out the fractions below and stick them in the
correct place on your fractionating column.
micfrv In, Vrv, 1irn. IP *ite I til
1 5fl
CIwnRvn

Tuesday, April 26, 2011

5.6 I can recall what crude oil is made form

a. Define the word hydrocarbon….
An organic compound containing only carbon and hydrogen
b. What is crude oil made from?
They were produced from the decay of tiny plants and animals millions of years ago.
It's also a compound of hydrogen and carbon
c. Define the word compound….
2 or more elements that are chemically joined-a pure substance
d. Define the word mixture…..
2 or more elements that are NOT chemically joined. Physically joined


4.       Read pgs 140 & 141 Chem 4 You and add these to the table above

d. How long does crude oil take to make?
150 millions years
e. Where does the energy in crude oil originally come from?
The sun
f. How is crude oil different from coal?
Coal was made from decayed plants under swamps, while crude oil was made by decayed plankton under the sea.
Also, coal is solid and crude oil is liquid
g. Crude oil, coal and natural gas are collectively known as _________ fuels
Fossil
h. How is crude oil transported when it is extracted from the ground?
By a pipeline or an oil tanker