Variables:
Independent variable: The concentration of salt solution
Dependant variables: There are two dependent variables, these are the length and mass of the chips
Controlled variables:
Apparatus:
Method:
1. Set up all the equipment
- Put on goggles
- Make the solution with the salt solution and distilled water
- Pour the solution into 5 specimen tubes
- Cut the potatoes into halves
- Take the cork borer and stick it into the potato
- Use the glass rod to take the potato out of the cork borer
- Cut into shape, measure and weigh them and cut out three chips for the solutions
- Put into the solution
- Next day take them out, weigh them and measure them, then write down the results
Results table:
Graph:
Conclusion:
Our experiment wanted us to find the best concentration of salt solution to store chips in. in my experiment I felt that there were some things that I didn’t do perfectly. Firstly I don’t think my chips were completely even and towards the end of the experiment I started rushing it slightly. Overall I think I done pretty well for a preliminary but could have improved it.
In my next experiment I will think of all of the things I need to improve in this experiment and do them perfectly in my main investigation. Also I will change the range of salt solutions from 5 to 11mol/dm3 because it allows me to maximise my results However I will not be changing my method or apparatus as do not see any room for improvement for my method nor my apparatus.
Main Investigation
From my preliminary report I know exactly what to do in my main investigation so this time everything is expected to go smoother and more accurate. Also I decided to keep the range of solutions the same as it is a wide range of solutions and will lead to better results
Prediction
My prediction remains the same as the prediction that I said for my preliminary which is that:
My prediction is that the low concentration solution (0 - 0.4) salt solutions will make the chips turgid because the solution will be hypotonic on the other hand the chips in the concentrated solution (0.6 – 1.0) will make the chips lack in firmness. So I think the 0.5 salt solution would be the best concentration to store the chips in because the solution will not make the chips absorb water nor loose much water because the solution would be isotonic which makes this the perfect concentration to store the chips in.
Variables:
Independent variable: The concentration of salt solution
Dependant variables: There are two dependent variables, these are the length and mass of the chips
Controlled variables:
Apparatus:
Safety:
- Keep your goggles on at all times. This will make sure that no harmful chemicals won’t go into your eye while you are doing the experiment.
- Follow all instructions carefully and if you don’t understand ask your teacher to clarify to you what you need to do because if you continue unknowing what to do in your experiment there’s a strong chance you could end up ruining your whole experiment.
- Never do an experiment alone without a teacher’s supervision as you could end up doing something wrong and it could end up disastrous.
- Be prepared to do an experiment. Make sure you know all of the procedures and safety rules before starting and never fool around in the laboratory as this could end up with you or someone else getting hurt
- Report any accident e.g. spillage or breakage or an injury to the teacher immediately, no matter how minor it is
- Only do experiments told by your teacher. Carefully follow all instructions. Unauthorised experiments should never be done as this will ruin your experiment and get you a zero
- Keep hands away from face, eyes and mouth while handling chemicals. Wash your hands with soap and water after doing the experiment as the chemicals could be hazardous.
Method:
- Set up all the equipment
- Put on goggles
- Make the solution with the salt solution and distilled water
- Label the tubes
- Pour the solution into 11 specimen tubes
- Cut the potatoes into halves
- Take the cork borer and stick it into the potato
- Use the glass rod to take the potato out of the cork borer
- Cut into shape, measure and weigh them and cut out three chips for the solutions
- Put into the solution
- Next day take them out, weigh them and measure them, then write down the results
Results table:
Graph
Conclusion:
Mathematically, to get our average mass change we had to add up all three of the initial mass and final mass, add them all up and divide them by three. Then we had to find the difference between the average of the initial mass and the average of the final mass.
E.G. 1.0 + 0.9 + 0.9 = 2.8 / 3 = 0.933 1.3 + 1.1 + 1.1 = 3.5 / 3 = 1.166 1.166 - 0.933 = 0.233
To get our average length change we had to do the same thing we did for the average mass change but to the length.
In conclusion I found that the best solution to store chips in was the 0.7mol/dm3 concentration of salt solution because the length stayed exactly the same and the mass only changes by 0.1 which means that the chips didn’t absorb or loose hardly any water.
Even though my main investigation was roughly accurate I feel that I could have made it better, so in my next experiment I will make my experiment as close to perfection as possible.
Evaluation:
- Did you collect enough results to draw a firm conclusion? How accurate are your results?
Yes I collected enough results from my preliminary report and from my main investigation and that allowed me to draw a firm conclusion my results for my preliminary are not very accurate but on the other hand my results from my main investigation were precise and accurate.
- Do all of your results support the conclusion that you have made? How many do not?
My results from my preliminary don’t support my conclusion but for my main investigation most of the results do support my conclusion. For my preliminary 6 of my results didn’t support my conclusion but for my main only around 2 didn’t so overall my preliminary didn’t support my conclusion but my main did.
- Do you think that the range you used was large enough to investigate the task set, and formulate a firm conclusion?
Yes the range I used for my solutions of salt was more than enough. I could easily make a firm conclusion with the range of salt solutions I used. If I needed to measure solutions with similar measurements as these salt solutions I would definitely use the range of salt solutions that I have used for this experiment.
- Have you collected enough data which is accurate and reliable to support a firm conclusion?
Yes I have collected enough data for my conclusion to rely on.
- Did you have any problems with your method?
I only had one problem that was on my first solution I put slightly more salt solution than I was supposed to by accident.
- Did you choose the most suitable equipment for your task?
Yes I chose the best equipment possible for my investigation.
- Did you control the other variables in your investigation? Do you think they varied during the experiment?
Yes I controlled all of the other variables in my investigation and most of them varied.
- How precise are your results? E.g. did you read off values or measure them using an instrument? Were the divisions on the equipment that you used small enough to record adequate readings?
My results were roughly precise however I feel that I could have made them even more accurate if I had done the experiment more slowly and carefully.
- What level of accuracy can you get from the equipment used?
I got a high level of accuracy from the equipment I used.
- What improvements can be made to obtain more accurate and reliable results?
To cut the chips more slowly and carefully.
- What extra measurements could be taken to make your conclusion more secure?
The investigation would have been better if the volume was measured.