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