H H H
H-C-O-H H- C - C - O - H
H H H
I chose Propan-1-ol (C3H7OH) and Butan-1-ol (C4H9OH) as these are examples of longer chain alcohols. This will be an advantage for my investigation because I have a contrast of short and long chain alcohols. This contrast will allow me to make a relationship between the long and short chain alcohols. I have also decided to put a branched alcohol compound into my investigation. This is 2-Methylpropan-1-ol (C4H9OH)This is an isomer of Butane and is also known as iso-butane. An isomer is a compound with the same molecular formula but different structural formula. This branched alcohol will add another variation to my results, which will also help in forming a relationship between enthalpy change and molecular structure.
Propan-1-ol Butan-1-ol 2-Methylpropan-1-ol
H
H H H H H H H H - C - H
H - C - C - C - O - H H - C - C - C - C - O - H H H
H H H H H H H H - C - C - C - O - H
H H H
The apparatus that will are needed for this investigation are;
- Five spirit burners, I need different spirit burners for each alcohol to stop cross contamination of the alcohols. This will give more results that are accurate and make it a fairer test as there will not be any mixed compounds.
- Copper Calorimeter, this will be used to store the water in and to help the heat transfer to the water.
- Heatproof mats, these will be needed for draught shielding so that as much energy as possible is reaching the calorimeter and water. The spirit burner could also be placed on a heatproof mat so the flame from the spirit burner reaches the calorimeter properly.
- A clamp stand, this to hold the calorimeter above the flame away from the spirit burner.
- Electronic weighing scales, This will allow a greater deal of accuracy when weighing the spirit burners. This will also help make it a fairer test as electronic scales are accurate to 2 decimal places.
- Measuring Cylinder, This will give accurate measurements for water. When taking measurements they must be taken at eye level.
- Thermometer, this is to help record the raise in water temperature.
- Safety goggles, these are to be worn at all times to prevent anything from entering the eye.
Risk Assessment (fig2)
Methanol and
Ethanol - These are both highly flammable. The vapour of these compounds catch fire above 13 centigrade. Inhalation of these alcohols has a narcotic effect on the body. If inhalation occurs, remove the victim to fresh air. If swallowed wash out mouth, and if victim shows drunk like symptoms consult a doctor.
Propan-1-ol - This is highly flammable, harmful and an irritant. There is a serious risk to eyes with this compound so goggles must be worn at all times when handling it. If it gets in the eye, flood it with water and seek medical attention. If swallowed wash out mouth. If inhalation occurs, remove the victim to fresh air.
Butanol-1-ol - This is flammable, harmful and an irritant. It is an irritant to the respiratory system, so if inhalation occurs seek medical attention. There is a serious risk to eyes with this compound so goggles must be worn at all times when handling it. If swallowed wash out mouth. If inhalation occurs, remove the victim to fresh air.
2-Methylpropan-1-ol - This is an irritant and also is flammable so care must be taken when handling. It is an irritant to the respiratory system, so if inhalation occurs seek medical attention. There is a serious risk to eyes with this compound so goggles must be worn at all times when handling it. Its vapour may cause drowsiness or dizziness. If swallowed wash out mouth. If inhalation occurs, remove the victim to fresh air.
This is the procedure, which is going to have to be followed for the experiments:
- Measure 100 ml of water in the measuring cylinder, when measuring the amount of water take the reading from eye level. Pour the water into the copper calorimeter. Take care not to spill the water.
- Place the calorimeter in the clamp stand (see fig1). Put a spirit burner underneath the calorimeter and make a note of which fuel is in the spirit burner so that, that fuel is not used twice. When you are handling a spirit burner consult the risk assessment (see fig2) about hazards for that alcohol.
- After making sure the copper calorimeter is a suitable height above the spirit burner, remove the spirit burner and then weigh the burner with the lid on.(When the burner is not in use always keep the correct lid on it)Record the weight.
- Check the length of the wick on the spirit burner, as this will affect the height of the flame. You should try to make all the wicks the same length to keep it a fair test.
- Replace the spirit burner back under the calorimeter, check if the wick touches the calorimeter. If it does higher the calorimeter so it does not touch any more. The calorimeter should be at least 3 centimetres above the wick.
- Use the Heatproof mats to form a draught shielding (see fig1) around the spirit burner and calorimeter to maximise the energy transfer between the spirit burner and the Calorimeter. Put the thermometer into the water and hold it there for a minute, not letting it touch the calorimeter and then record the start temperature.
- Light the wick of the spirit burner, stir the water with the thermometer continuously. When the water has increased by 13c-15c replace the lid on the spirit burner, but keep the thermometer in the water still not letting it TOUCH the calorimeter for another two minutes as heat is still being transferred to the water from the calorimeter. Record the temperature after these two minutes.
- Weigh the spirit burner again making sure the correct lid is put back on the burner, Record this weight in your results table.
There are a number of variables to take into consideration when keeping the investigation fair these are;
- Keeping the lid on the spirit burner when it is not being used so there is no loss of mass due to evaporation.
- Cleaning the copper calorimeter in between each different spirit burner to stop soot build up. Soot build up on the calorimeter reduces the amount of energy which can be transferred to the water.
- Another problem is trying to keep the temperature of the calorimeter the same each time the experiment is conducted. Extreme difference in temperature would result in a unfair test.
- Another problem is that the water temperature rise is not going to be the same every time the experiment is conducted.
Bibliography
In devising my plan I have used the following information sources;
Salter’s Advanced chemistry activity sheet 1.2
Salter’s Advanced chemistry chemical ideas
Heinemann advanced Chemistry.
CLEAPSS 2000 Hazard cards.
