Equipment:
- Three different types of peanuts and a pea.
- 25cm³ measuring cylinder: to measure the water accurately.
- Goggles: for safety from fumes emitted by burning peanuts.
- See through test tubes: to read the thermometer and to put water in.
- Test tube rack: to hold test tubes.
- Needle and a cork (connected): to hold the peanut safely while and after heating.
- Thermometer: to measure the temperature.
- Water
- Stand and an adjustable clamp: to hold the test tube above the base for safely.
- Bunsen burner: to heat the peanuts and pea.
- Heat proof mat: for safety.
- Weighing scale: for weighing peanuts.
- Timing watch: to record time.
In order to make my investigation fair, I planned to do the following:-
- Investigate which factors will affect my project.
- Produce a list of solutions which are likely to work.
- What I will keep and what I will change.
The main factors that will affect my project are:
- The amount of water and it will be measured using a measuring cylinder.
- The peanuts held the same distance apart from the test tube.
- The blue flame will be directly under the peanut to obtain optimum results.
- Remove the Bunsen burner away from the peanut, for safety and accuracy because it might affect the surrounding temperature and could affect my results.
- Measure the temperature of the thermometer in the water and make sure that all thermometers have the same temperature to make the test fair.
- The test tubes were all of the same size, because if the base of one test tube is bigger than another and if I heat both of them, the results will turn out different because one base would receive heat faster than the other.
- I must record the temperature every 10 seconds for 90 seconds.
- The way the temperature is recorded (horizontally, diagonally).
- Heat loss can affect my results because when the heat of combustion is transferred to the water, energy could be lost to the air, thermometer or test tube.
Health and safety:
Safety must be considered wisely because there is a theoretical link between peanut smoke and carcinogens. Also, as fire is present, it will be considered dangerous to sit down because if a disaster happens, students might struggle to leave the seats. Goggles must be worn at all times and also blazers and ties must be removed or kept out of sight to prevent them from catching fire. Put flammable materials such as Tip-ex away. The windows in the class room must be opened to keep the room well ventilated from dangerous fumes. Hot equipment will be dealt with carefully: if we finish with the needle and it is hot, I would not touch it, I will not touch hot objects with my hands such as the Bunsen burner. Heat proof mats are used to prevent the desks or bases from overheating. When I heat the test tubes and have the flamed peanut in my hand I will concentrate and will not look at any one.
Preliminary work:
I first started with an extravagant amount of water (20cm³); logically it seemed to be too much because one peanut which has a mass of 0.3 grams cannot heat up an extravagant amount of water. So I decided to use 5cm³ instead because there are less particles, therefore less energy will be required to raise the temperature. I used the pea in the investigation, albeit it was suppose to be considered as a peanut, I concluded straight away from the experiment that the pea has a small amount of energy because the temperature did not reach a similar value to those of the other peanuts. It must be because the pea is dry, therefore less oil-less fat.
Method:
- Using the weighing scale, measure the three peanuts (plain salted, roasted and dry roasted) and pea and record their weights for accuracy and fair testing.
- Get a cork-needle (mounted) and stick the needle into a peanut or a pea from a slight angle slowly and smoothly, to prevent the peanut or pea from breaking into pieces. (Heated if necessary, depending on what peanut or pea is used, (after setting up Bunsen burner on step6)).
- Set up a stand, and an adjustable clamp held near the top to hold the test tube.
- Get two test tubes and by using a measuring cylinder, add 5cm³ of water into each one respectively.
- Put the test tubes into a test tube rack while setting up other equipment.
- Wear goggles and get a heat proof mat, set up a Bunsen burner on it (connect the Bunsen burner to a gas pipe)
- Put a thermometer in water and record its temperature.
- Hold a test tube using the clamp firmly and keep the thermometer to measure the temperature elevation.
- Place a Bunsen burner on a heatproof mat and start the fire on the Bunsen burner, turn the flame to blue flame to get the optimum results.
- Hold the peanut or pea using the cork handle directly on top of the Bunsen burner and heat a peanut or pea until it catches fire.
- Make sure Bunsen burner is turned off.
- Place the flaming peanut or pea directly under the test tube of water, as soon as this is done…. (keep the needle the same distance apart from the test tube).
- Timer watch must be started
- Record the temperature rise each ten seconds as accurately as possible for 90 seconds.
- Repeat process for all the other peanuts or pea.
Observation
My experiment was based on the method above and I gathered all the necessary information to make sure that my results would be as precise as possible to the true figures when I compare them with existing products.
I observed temperature change when the flamed peanuts were put directly under the test tube of water and thermometer.
I measured the peanuts by using a weighing scale and I used a couple of peanuts each time to select the weight I desire. After all the peanuts were selected, I decided to draw tables to insert the results I will obtain. I felt that the units are really important to include because they would determine my final results after using the Energy formula. I set up all the equipment listed above correctly and safely. I decided to put the Bunsen burner off after each peanut was burnt, although it would be time consuming but I believe that the outcome would be more accurate. If the Bunsen burner was kept close to the experimental apparatus, then it would affect the temperature and for some trials it would be unfair and inaccurate. It was quite hard to insert the cold tipped needle into the delicate peanuts so I decided to use the Bunsen burner to heat it, I observed that it was much easier to insert the needle into the peanuts when it is hot. This prevented the peanuts from splitting into pieces. I used a clamp to hold the test tube because it was safer and more accurate. The best amount of water (variable) I selected from all the preliminary tests was 5cm³ because it meant that fewer particles would have to be heated and also it would be more accurate to get 5cm³ on the measuring cylinder. I recorded the temperature by standing horizontally to the thermometer, if I look at the thermometer from a steep angle, my results would be unfair. I also noticed that using a see through test tube would help me obtain precise results because it would be easier to read off the temperatures. Furthermore, I felt that timing is one of the main factors that would affect my overall results so I decided to repeat the experiment three times for each peanut. I did the experiment for the pea as well, but I decided not to include it in my research because it is obvious that it emits that least amount of energy. I deduced that if I use the same equipment for each experiment, the results would be more accurate especially if the equipment was kept in the same position. I used a predicted method which was not in order and did not include all the necessary steps.
The most important observation I made was noticing the evaporation of the water, and the assembled dark black carbon monoxide at the bottom of the test tube. This suggests that carbon combined with the oxygen in the atmosphere.
I do not think that all the energy released by the peanuts went into the water and all that did, possibly escaped through air, thermometer or test tube. The combustion reaction was present in this experiment: The peanut gained energy from the flame and as it did so, it had enough energy to combine with the surrounding air so it began to burn. I assume that some energy was lost when bringing the flamed peanut from the Bunsen burner to the test tube. I did not put the burnt peanuts in the sink. I mainly focused on the variables: factors which are measured or controlled. I identified that my experiment was based on dependent and independent variables. The temperature was dependent and the time was independent because I can control it. I also observed that my variables were continuous because they did not take particular values.
Analysis
Conclusion:
My conclusion agrees with my prediction. I can conclude from my graphs that a plain peanut contains more energy than the roasted and dry roasted peanuts, this is because the plain peanut had not been subjected to heat while the roasted and dry roasted did, this means that these peanuts lost heat previously while the plain peanut is still unaltered. Also, it is because of the weight, at the start, the plain peanut was double the weight of all the other peanuts and when I took an average, the figures were not precise. I conclude that the roasted and dry roasted peanuts were close together in the graph at the beginning but then at 50 seconds, the roasted peanut became more dispersed than the dry roasted. The roasted peanut measured 6 degrees less than the plain peanut towards the end. Because the plain peanut had a greater mass (also no heat exposure), which means it contained more fat and more fat burns; more energy. If we consider this in the evaluation, next time I will get more precise results. I conclude that a certain amount of energy was added to the peanut before it began burning because some energy is needed to start the process (activation energy). All the results used in the investigation are an average which means they are not precise but probable. There is a pattern in my results be cause the curves were juxtapositioned. What happened is that the oxygen caused the peanut to catch fire and then, this energy (heat) was being transferred to the test tube which had water. The liquid molecules were vibrating and this caused evaporation. All this is done by the heat given by the peanuts; the main energy came from the Bunsen burner. This experiment is similar to the respiration process: (The arrows mean 'as an out come by heat')
Respiration: fatty acids + oxygen carbon dioxide + water + energy
Experiment: peanut (oil:fats:glycerol and fatty acids) + oxygen Carbon dioxide + water + energy.
I used the following formula to calculate the energy in peanuts: E = m × θ × ∆t
I conclude that if oxygen and fat molecules combine, as an outcome, energy will be produced. The main source of energy for the peanuts is the sun, and as peanuts are grown in hot countries, a lot of photosynthesis will take place; therefore more energy is stored.
Therefore, from my graphs, I can conclude that energy was released in all three peanuts; also the longer the fire on the peanut, the more energy is emitted. I can also conclude that fat burns best at higher temperatures.
I believe that my results were quite accurate for the energy present in each peanut. The dependent variables affected my results. I can also conclude that my experiment is exothermic because energy was given out.
The evidence gathered is enough to support my conclusion.
Evaluation
My results in general were reliable, especially after considering the weights and averages because these do not give a precise result.
I had one anomalous result, and it was in the plain peanut (50, 50), this point is off and destroys the results pattern. I discounted this point in the graph because it is way out of the pattern and it is an experimental error. When discounted and not taken into consideration, the plain peanut would have a completely smooth curve. The procedure in this experiment was quite difficult because time was limited, perhaps if more time was spent, the results would be very near to the true figures. I measured the energy in Kilojoules per gram, and per 100 grams. The quality of the accuracy would be much better if we did not take an average, albeit it will take longer but more exact results could be obtained. I think that this experiment was fair because I used the same measuring cylinder 25cm³ for each test tube, the weighing scales were used accurately and were clear of any objects that could affect the results obtained, the Bunsen burner was put away from the practical to that it would not affect the results by adding heat to the surrounding environment. I can improve my accuracy by reading the time against temperature fasted and record it. By looking at the thermometer from a horizontal angle the results would be more accurate. The accuracy and quality can be improved by spending a longer time on the coursework. If I have the opportunity to repeat the experiment, with the experience I now have, I will try to use different apparatus such as the calorimeter to get a better result. I would add a different variety of foods next time such as cashew nuts and crisps, because I would like to find out how much energy there is in both of them, how many calories and which one contains more fat. If I can do this experiment again, then I would use the same method but a different technique to manipulate the equipment to gain the best results. I used a mounted needle to hold the peanuts and I had difficulty inserting the needle into the pea, and peanuts with out breaking them into pieces.
Next time I could keep the remains of the burnt peanuts and subtract the final mass of the peanut from the initial mass to find out how much mass is burnt. Also, I could use different amounts of water to check if the energy stays the same or becomes different. Also, I could keep the needle the same distance(close) away from the test tube so energy will not be lost.
To investigate even further, next time I plan to relate the speed of the reaction (how fast energy goes up compared with heat).
