Thursday, September 1, 2011

Advantages and Disadvantages of 2 Methods of Creating Alcohol



Advantages
Disadvantages
Fermentation
·      Renewable recourses (sugarcane 
·      Little energy needed (gentler temperatures)
·      Doesn’t produce harmful gasses
·      Production is slow
·      Product is impure
·      Its expensive
·      Many people are needed to produce it (Batch process - inefficient)
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 (oil)

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 (l) --> bromoethane + hydrogenbromide 
                                         or dibromoethane 


2.       Draw the displayed formula of the reaction above


3.       Explain the observations
The liquid turns from brown/ yellow to colourless because the bromine molecules are separated and loses it's colour
4.       Why does this reaction not need a catalyst?
 A catalyst is not needed because alkenes and the carbon carbon double bond is very reactive.

5.       What type of reaction is this called?
This is called an addition reaction

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

Tuesday, June 7, 2011

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


What is the General formula of Alkanes?     CnH2n+2
 Describe the Trend in Boiling Points: A straight-chain alkane will have a boiling point higher than a branched-chain alkane due to the greater surface area in contact with the heat source, also, as 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
 A family or series of Hydrocarbons that have similar chemical properties.

 Alkanes
Alkenes
Hydrocarbon
 Organic compounds that consist of only Hydrogen and Carbon

 Ethanol
Saturated hydrocarbon
 Alkanes (paraffins) - hydrocarbons that have a carbon 'skeleton' or 'back-bone' 
Hydrogen must have 4 bonds

 Methane
Unsaturated hydrocarbon
 Alkenes (olefins) - Hydrocarbons with at least one carbon to carbon double bond.

 Ethylene
General formula
 Within a series; it shows the relationship between the number of C atoms and H atoms in the compounds

Alkanes - CnH2n+2
 Alkenes - CnH2n.
 Hexane C6H14
Propene C3H6
Isomerism
 Isomers have the same formula but their atoms are arranged differently. 
Different physical properties

 Propane

Friday, May 27, 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.
3.       What is this type of reaction called A substitution reaction 
4.       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 
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 à C2H5 + HCl

7.       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

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



1.       Saturated hydrocarbons are called alkanes
2.       Small chain hydrocarbons are used as fuels
3.       The reaction is called a substitute reaction
4.       The word equation for  this chemical reaction is :
fuel (hydrocarbon) + oxygenCarbon 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? Car engines
8.       What is used to reduce the harmful products from incomplete combustion? Catalytic Converters 
9.       During incomplete combustion a smoky flame is often seen, explain this observation

During incomplete combustion a smoke is seen, this is solid carbon that has not reacted during the combustion reaction


Write a balanced equation (with state symbols) for the combustion of propane gas


C3H8 + 5O2 --> 3CO2+4H2O

10. Describe the two chemical tests for Water: 
Copper 2 sulphate powder: white- blue 
colbalt2 chloride litmus paper : blue- pink

Tuesday, May 17, 2011

5.13 I can describe catalytic cracking of long-chain hydrocarbons

Read "Chemistry For You" Page 145


Catalyst - A catalyst is a substance that has the ability to change the rate of reaction


Why are catalysts used? - Catalysts are usually used in order to speed up reaction rates, they can also slow them down, for instance to postpone rusting.


Why are high temperatures needed? - High temperatures are needed for the amount of energy the molecules need to react, it also speeds up the rate of reaction.





What equipment is used during the process? 
A boiling tube with a delivery tube with a test tube or reservoir and a basin of water.


What catalysts are used to convert long chain alkanes to alkenes and shorter chain molecules? - Silica or alumina. Video > A ceramic catalyst can be used (silicon)

How is the Gas collected? 
Over water

What safety aspects are preformed during the experiment?
The gas will be collected over water, do not allowed suck-back of water ( it will turn into steam and cause and explosion)

What causes the cracking to occur? 
Video > first you must heat the ceramic pot (catalyst) and then move the flame which will encourage the liquid paraffin to turn into a vapour and meet the catalyst, this causes the cracking to occur.

What is Cracking? 
When the Long Chain gas molecules produce smaller chain gas molecules which will then be collected. (In the Video > triggered by ceramic catalyst)

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 short chain hydrocarbons (eg refinery gases)

b. To solve these problems the long chain hydrocarbons undergo a chemical reaction called crackin (see objective 5.13)

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 Temperatures and presence of Oxygen
d.      In what common object is this condition found?
        Cars
e.      Why is this condition needed for nitrogen to react?
       Because Nitrogen molecules are diatomic and have strong triple covent bonds
f.        What are the dangers of the products from this reaction?
        Asthma, Acid rain and Cancers. 

5.7 I can describe how crude oil is separated



Wednesday, May 11, 2011

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



3 minutes 4 Seconds

a.       What is the trend in boiling point of the fractions? - As you go up the fractionating column the boiling point decreases 
b.      Define viscosity (source your definition)  - Resistance of a liquid to shear forces (and hence to flow) or the thickness of a liquid 
c.       What is the trend in viscosity of the fractions? - The higher the boiling point the greater the viscosity 
d.      What is the trend in colour of the fractions? - The higher the boiling point the darker the colour


e.      Why is crude oil separated into fractions? - Because each fraction has a different use whilst Crude oil unseparated is virtually useless
f.        What process is used to separate crude oil into fractions? - Fractional Distillation 


g.       What physical property allows this process to work? -  Boiling point


Description: Machine generated alternative text: small molecules
crude oil
is heated
and enters
as a vapour
.
o
0
I petroleum
gases
(such as propane
and butane)
petrol
(gasoline)
• low boiling point (volatile)
. light in colour
easy to light and
bum weU (flammable)
. runny
large molecules
. high boiling point
. dark in colour
. hard to light
• viscous or thick
(if still a liquid at
room temperature
— bitumen is a solid)
low
temperature
I
(paraffin)
kerosine
diesel
lubricating
oil
I heavy fuel
oil
high
temperature
360C
I
bitumen
Image taken from Chem 4 You pg 144

5.10 I can recall the problems associated with incomplete combustion






1.       What are the properties of carbon monoxide
 - Carbon Monoxide is an odourless tasteless gas that is very poisonous. 

2.       Explain how carbon monoxide is formed
- Carbon Monoxide is formed when there is the event of incomplete combustion - this occurs due to insufficient amounts of oxygen during a combustion reaction.

3.       Explain why carbon monoxide is poisonous
- Haemoglobin's attraction to Carbon monoxide is much greater than it's attraction to oxygen, the gas is not used in respiration and therefore remains circulating in the respiratory system, all of the haemoglobin is already bonded to the Carbon Monoxide and eventually starves all organs of Oxygen. 

Tuesday, April 26, 2011

5.6 I can recall what crude oil is made from



 Page  139 

a. Define the word hydrocarbon….
An organic compound consisting entirely of hydrogen and carbon
b. What is crude oil made from?
A mixture of hydrocarbons; it is produced through the deterioration of organisms under layers of earth
c. Define the word compound….
A substance consisting of two or more elements that are chemically bonded 
d. Define the word mixture…..
A substance consisting of two or more parts (elements or compounds) that are not chemically bonded. 

      Read pgs 140 & 141 Chem 4 

d. How long does crude oil take to make?
millions of years
e. Where does the energy in crude oil originally come from?
The sun
f. How is crude oil different from coal?
Coal is not a hydrocarbon - contains more than hydrogen and carbon. They are also in different states of matter when in room temperature. Crude oil is made from decayed plants and animals where coal is solely made from decayed plants.
g. Crude oil, coal and natural gas are collectively known as _________ fuels
Fossil (Non-renewable
h. How is crude oil transported when it is extracted from the ground?
To move oil from oilfield to the refinery 
i) By pipeline - When oil is reasonably close to the refinery
ii) oil tanker - large ships can transport oil internationally but increased risk of accidents (Oil Spills)