Alcohol Combustion Plan Essay Example

following equation Energy transferred = cm T = specific heating capacity of water (4. 17Jg-1K-1) m = mass of water (in grams) ?T = change in temperature of the water. Enthalpy change depends on the bonds that are being broken and the bonds that are being formed in a chemical equation. For example the combustion of methane: This diagram shows the different bonds that are being broken (the left hand side), and also the bonds being formed (the right hand side) in the chemical reaction of the combustion of methane. Also shown is the amount of energy needed to break and form these bonds (these energies are the same).The different bonds on either side of the equation show that different energies are needed to break and form the different bonds. So in my experiment the alcohols will have different enthalpy levels because different amounts of bonds are being broken and formed. My choice of alcohols / predictions The first few alcohols of the homologous series along with their structural formulae and combustion equations are as follows: Methanol Ethanol Propanol Butanol Pentanol From these balanced equations we can see that when one mole of the alcohol is burnt the alcohol needs 1.

mol more oxygen, and produces one more mole more of carbon dioxide and one more mole of water vapour. •So based on this I predict that when I measure the enthalpy change of combustion of the homologous series alcohols the enthalpy change should go up in pattern. However isomers of the same alcohol shouldn’t show any difference. For example if we compare the alcohols Butanol and it’s isomer propan-2-ol. Butanol Propan-2-ol •In both

alcohols there are the exact same bonds that will be broken; the exact same bonds will be formed in the products.Because these bonds have the same energy requirements for breaking and forming the enthalpy change in combustion will be the same for an alcohol and its isomer.

So based on these two properties of alcohols I will experiment the enthalpy change of combustion with following alcohols: ?Ethanol ?Propanol ?Butanol ?Propan-2-ol ?2-methyl Propanol Equipment To carry out the experiment the following equipment is needed: -A small copper can or other metal container to act as calorimeter (the base diameter should be at least 8cm) -0 - 110°C thermometer or 0 -50°C thermometer if available -Spirit burners containing liquid fuels of :Ethanol Propanol Butanol Propan-2-ol 2 – MethylPropanol -Access to a balance -Bunsen Burner -Draught shielding Method 1. Put 200cm3 of cold water in a copper calorimeter and record its temperature. 2. Support the calorimeter over a spirit burner containing the liquid fuel you are going to test. Arrange a draught exclusion system.

Other features to minmise heat loss can also be used. 3. Weigh the spirit burner (to a sensible degree of accuracy) 4. Place the burner under the calorimeter and light the wick of the burner. 5.

Stir the water all the time that the water is being heated; the thermometer can be used for this. Do this until the water has risen in temperature by about 15 – 20 °C. 6. Extinguish the burner and keep stirring. Note the highest temperature reached.

7. Reweigh the burner to see what mass of fuel has been burned. This must be repeated for each of the five liquid

fuels. Measurements should be recorded in a suitable table. Risk assessment The main risk with an experiment like this is that the Bunsen burner may cause a fire.

To avoid this from occurring the following precautions must be taken: -work in a cleared area with only necessary equipment on the worktop -Only light the Bunsen burner when it is needed -Tie back hair and any other loose garment (e. g. scarf and jackets) Also I have collected information on the hazards regarding my fuels; which I have summarized here; Ethanol: Causes skin and eye irritation. Ingestion can cause nausea, vomiting and inebriation; chronic use can cause serious liver damage. Propanol: Has been found to cause cancer in laboratory animals.

Skin, eye and respiratory irritantButanol: Harmful by inhalation, ingestion or skin absorption. Irritant. Narcotic Propan-2-ol: May be harmful by inhalation, ingestion or skin absorption. May act as an irritant. 2-MethylPropanol: Harmful by inhalation or ingestion. May cause narcosis.

Skin, eye and respiratory irritant. I think that these risks are generally applicable to situations where large amounts of the substance are being handled. Also because the liquid fuel is within the spirit burner i think that there is also less risk. However I think that a small fire extinguisher should be on hand.

Goggles should also be worn. ReferencesThe following sources were used to gather some of the information used in this investigation plan: 1-Chemical Ideas (second edition) 2-http://physchem. ox. ac.

uk/MSDS/#Disclaimer (website) 3-Google image search—enthalpy changes of combustion - www. teachmetuition. co. uk Source 1 was used for information on bond breaking and bond formation. Source 2 was used for information on the hazards and risks with

my alcohols.

Source 3 was used for the endothermic and exothermic enthalpy change graphs. Results Fueltemp of water (°C)Weight of spirit burner (grams) startendStart end Ethanol Propanol Butanol Propan-2-ol 2-methylpropanol