Thursday, September 1, 2011

Advantages and Disadvantages for 2 methods of creating alcohol



Advantages
Disadvantages
Fermentation
·      Renewable recourses
·      Little energy needed
·      Doesn’t produce harmful gasses
·      Production is slow
·      Product is impure
·      Its expensive
·      Many people are needed to produce it
Industrially
·      Product is pure
·      Not that many workers are needed as they have machinery
·      Production is very fast
·      Lots of energy is needed
·      High temp. and pressure conditions are needed
·      Non renewable

Tuesday, June 21, 2011

3.8 I can describe the reaction between alkenes and bromine

1.       Write the word equation showing the reaction between ethene and bromine water
          ethene + bromine water ---------> bromoethane + hydrogenbromide
2.       Draw the displayed formula of the reaction above

3.       Explain the observations: liquid turns from brown/orange to coloress
4.       Why does this reaction not need a catalyst? because the carbon - carbon double bondsmake the alkenes very reactive
5.       What type of reaction is this called?Addition reaction.

6.       Explain why this reaction is useful
Because it is shows when a  non-saturated bond is present.

Tuesday, June 7, 2011

3.5 I can recall the reaction of methane and bromine

Alkanes react with bromine in the presence of UV Light
     Explain why this condition is necessary  UV light is the source on energy in order to break the weak inter molecular forces in between molecules.
  What is this type of reaction called A substitution reaction 
 State and explain the observations - Alkanes are colourless and bromine is brown, when the reactants are given energy to break intermolecular bonds the bromine is less saturated and the product is therefore colourless 
Write out a balanced (with state symbols) the reaction between ethane and chlorine
C2H+ Clà C2H5 + HCl
 State and explain the observations in this chemical reaction
The chorine begins as a green/yellow gas, when it reacts the chlorine is less saturated and the product is more saturated making the product colourless
Displayed Formula of reaction between methane and bromine : 



Friday, May 27, 2011

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

1.       Saturated hydrocarbons are called alkanes
2.       Small chain hydrocarbons 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 poison to the human body (see objective 5.11)
7.       Where can you find incomplete combustion? in car engines
8.       What is used to reduce the harmful products from incomplete combustion? catalytic converter
9.       During incomplete combustion a smoky flame is often seen, explain this observation. solid carbon that has not reacted
Extn: write a balanced equation (with state symbols) for the combustion of propane gas

C3H8 + 5O2 ---> 3CO2 + 4H20

Tuesday, May 24, 2011

3.2 and 3.3 I can recall the general formula and displayed formulae of alkanes

What is the general formula for alkanes?      CnH2n+2
Describe and explain the trend in boiling point: A straight-chain alkane will have a boiling point higher than a branched-chain alkane due to the greater surface area in contact and the mass of the alkane increase the boiling point increases
Draw the displayed formula of the three isomers of pentane:



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


Term
Definition
Example
Homologous series
 having the same functional group but differing in composition by a fixed group of atoms
 alkane
Hydrocarbon
 Compound of hydrogen and carbon

 Alkenes, alkanes
Saturated hydrocarbon
 Have single bonds

 alkanes
Unsaturated hydrocarbon
 Have double and/or   single bonds

 alkenes
General formula
 Series it shows the relationship between the number of C atoms and H atoms in the compounds

  for Alkanes it is CnH2n+2
for alkene it is CnH2
Isomerism                   
 compounds with the same formula but a different arrangement of atoms in the molecule and different properties
 2,2dimethylpropane

Tuesday, May 17, 2011

5.13 I can describe catalytic cracking of long-chain hydrocarbons

1) define the word catalyst: a substance that changes the rate of reaction
2) why is catalyst used? to speed up the reaction rate of cracking, they can also slow down reactions such as for rusting
3) why are high temperatures needed?high temps are needed to break the strong covalent bonds in the hydrocarbon 



What types of catalysts are used for cracking? silica and alumina
What equipment do you need to collect the gas? boiling tube, a basin full of water, delivery tube.
What hydrocarbon is he cracking? paraffin
How are alkanes tuned into alkenes? through cracking with either silica or alumina as the catalyst
At what temperature can this experiment work at? 600-700 degrees celsius

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

Read chemistry for you page 145

a) when crude oil undergoes fractional distillation there are too many long chain hydrocarbons (eg bitumen     ) produced and not enough shorter chain hydrocarbons (eg refinery gases)
b) to solve these problems the large 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 + oxygen -----> energy + oxides
b.      During combustion the nitrogen in air can react to form what gases? NOx gases
c.       What condition is necessary for the formation of these gases? high temperature
d.      In what common object is this condition found? in cars
e.      Why is this condition needed for nitrogen to react? they nitrogen molecules are diatomic and have triple covalent bonds 
f.        What are the dangers of the products from this reaction? asthma, cancers, acid rain

Tuesday, May 10, 2011

5.10 recall that incomplete combustion of fuels may produce carbon monoxide and explain that carbon monoxide is poisonous because it reduces the capacity of the blood to carry oxygen





What are the properties of carbon monoxide? Clear, odorless gas, cant see it, highly poisonous
Explain how carbon monoxide is formed? Through incomplete combustion when there is insufficient oxygen
Explain why carbon monoxide is poisonous? it binds very strongly to hemoglobin, when it attaches, it is very difficult to release, when you breath in carbon monoxide, it sticks to your hemoglobin and takes up the oxygen binding sites. and your blood loses ability to transport oxygen, and you suffocate.

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

a.       What is the trend in boiling point of the fractions?        as you go lower the fractions the boiling point gets higher             
b.      Define viscosity      the thickness of a liquid       
c.      What is the trend in viscosity of the fractions?   higher viscosity towards the bottom of the fractionating column 
      What is the trend in colour of the fractions?        colour gets darker when fractions have a higher viscosity
e.      Why is crude oil separated into fractions?      Crude oil on its own its useless, when extracted it has lots of uses
f.        What process is used to separate crude oil into fractions? Fractional distillation
g.       What physical property allows this process to work? each fraction has  adifferent boiling point

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

Tuesday, April 26, 2011

5.6 I can recall what crude oil is made from.

2.       Read pg 139 (down to word plastics) Chem 4 You

a. Define the word hydrocarbon….
 compound of hydrogen and carbon
b. What is crude oil made from?
several hydrocarbons and plants and animals from millions of years ago
c. Define the word compound….
2 or more different elements chemically bonded together
d. Define the word mixture…..
several compounds or elements not chemically bonded
4.       Read pgs 140 & 141 Chem 4 You and add these to the table above

d. How long does crude oil take to make?
about 150,000,000 years
e. Where does the energy in crude oil originally come from?
the sun
f. How is crude oil different from coal?
crude oil came from plants and animals from the sea and oil came from trees that were under swamps and crude oil is a hydrocarbon and oil is not
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?
either pipeline or with oil tankers which bring the oil around the world