Planning
My aim for this experiment is to see the energy produced of different alcohols.
Variables involved:
For this experiment I would expect to have 3 different variables, Independent, Dependent, and fixed variables, which all helps me to plan and explain the experiment thoroughly.
The Independent variable (things you change), the thing that I will be changing in this experiment into the combustion of a range of alcohols, would be five different alcohols, Methanol, Ethanol, Propanol, Butanol, and Hexanol, which will help me to investigate combustion of different alcohols. I will measure these individual alcohols by mass which will be measured in grams, I'll be making two readings of each alcohol before the experiment and after, which would tell me the mass lost and how much heat in produces in 5 minutes.
Dependent Variable (things that you measure) the things that I'll be measuring would be the temperature (oC) increase by every minute of each different alcohol being lit to heat the water in the copper calumeter, and the mass before and after the experiment of alcohols.
Fixed Variables (Things that you keep the same) the things that I have chosen to keep the same in each individual experiment to keep it a fair test, is to keep the same amount of water being heated, the same copper calumeter (as it may very in conductivity), the height of the calumeter, and the same amount of time for each experiment. This would help me to compare and analyse the results of the individual experiments.
Hypothesis:
My prediction for this experiment on investigating the energy produced by different alcohols is that, the longer the hydrocarbons in the chain of the alcohols, the more heat it will produce. As the alcohols are being lit by the waxy splint that produces heat, it will also give out oxygen and water as well as heat energy to heat the water, which will crack the hydrocarbons into simpler molecules (smaller) and then will combust later, making this experiment an exothermic reaction. Therefore the long chains of hydrocarbons produce more energy than smaller chain molecules as the long chain breaks in to smaller hydrocarbons meaning theirs more, making the boiling point decrease, which makes them more flammable, less viscous, and more volatile. Therefore I would expect that when the alcohol's is being burned and producing heat energy, carbon dioxide, and water will be produced meaning the alcohol would lose some mass which would evaporate into the air. I therefore predict that when there is a longer chain of hydrocarbons than another alcohol, it would produce more heat than the other alcohol meaning it would have a higher reading each minute compared to a smaller chain of hydrocarbons, which could mean that the smaller hydrocarbons combust quicker then longer hydrocarbons as their less volatile.
Scientific explanation of what would happen:
When each alcohol is burned to give out energy to heat the copper flask I would expect each of the following would happen to each alcohol I have listed below. Looking at all the alcohol's I have noticed that they're all alkanes, which means that they all have single bonds. This means that the alcohol's are made up of chains of carbon atoms with single covalent bonds between them, which are called saturated hydrocarbons because they have no spare bonds left meaning they won't form polymers. All the five alcohols would have complete combustion, which relates to this equation below.
Hydrocarbon + water carbon dioxide + Water (+ energy)
Methanol (CH3OH) would burn with a very clean flame, produce the least amount of energy as they have the least amount of hydrocarbons. This is because they only have 1 carbon atom, which combust in the shortest amount of time, out of the 4 other alcohols.
This is the complete combustion balanced equation showing methanol heated with carbon dioxide and water.
CH3OH + 11/2O2 CO2 + 2H20
Ethanol (C2H5OH) will burn with a very clean flame, produce the second least amount of heat energy as they have the second least amount of hydrocarbons. This is because they have only 2 carbon atoms in the 5-hydrocarbon chain, which will combust and be used in forms of heat energy really fast compared to Hexanol.
This is the complete combustion balanced equation showing Ethanol heated with carbon dioxide and water.
C2H5OH + 3O2 2CO2 + 3H2O
Propanol (C3H7OH) would burn with again a very clean flame producing heat energy between the ethanol and butanol alcohols. This is because the ethanol alcohol has 2 carbon atom and butanol has 4 carbon atoms, where as propanol has 3 carbon atoms producing more heat energy then propanol.
This is the complete combustion balanced equation showing Propanol heated with carbon dioxide and water.
C3H7OH + 41/2O2 3CO2 + 5H2O
Butanol (C4H9OH) would produce more heat energy then propanol and will combust longer than propanol as it has more hydrocarbon chains as it started off volatile before heating it, which then gets heated to crack the hydrocarbon chains to make them produce more heat energy.
This is the complete combustion balanced equation showing Butanol heated with carbon dioxide and water.
C4H9OH + 6O2 4CO2 + 5H2O
Hexanol (C5H11OH) would produce the most amount of heat energy as it has the most amount of hydrocarbon chains with the most carbon atoms, which crack into simpler forms to become more volatile, less viscous, more flammable and produce loads of energy in forms of heat.
This is the complete combustion balanced equation showing Hexanol heated with carbon dioxide and water.
C6H11OH + 81/2O2 6CO2 + 6H2O
Apparatus I will need:
· Copper calumeter,
· Water,
· Thermometer,
· Timer,
· Measuring cylinder,
· Alcohols, (sprit lamp)
· Bunsen burner,
· Retort stand,
· Clamp,
· Weighing balance,
Diagram:
I have drawn a diagram of what the experiment will look like seen below. I have chosen the best equipment given to me to carry out this investigation thoroughly.
