The controlled variable is the mass.
INSTRUCTIONS
In this experiment the masses and volumes of ispirto will be measured. Ispirto is a mixture of methanol and ethanol (in unknown proportions). Several trials can be made in order to make the experiment precise.
The materials are 1L of ispirto, beakers, a beam balance and some measuring cylinders.
Method:
- Decide what volumes of methylated spirit you will use for this experiment, according to limitations of the equipment.
- Measure the mass of the empty beaker using the beam balance and then record it on your raw data.
- Pour the correct amount of ispirto that you have decided and then record its mass and volume on your raw data table.
- Repeat these steps 8 or more times to get more precise results.
- Draw a suitable graph that will allow you to determine the density of methylated spirit.
- Determine the density of ispirto and give the range of possible values that this can have according to your results.
Raw Data
Mass of the beaker = 65.1 +- 0.1 g
Processed Data
CONCLUSION
The final result of this experiment is 7.83 x 102 +- 3.0 kg m-3.
The beam balance’s parts inside had friction, so it effected the value of the mass of the ispirto.
There is no need for maximum and minimum slope.
EVALUATION
The beam balance’s parts inside had friction, so when something is put on the balance the value we get is smaller than the real value. When we empty the beaker there are still some ispirto left in the beaker, so it cannot be fully emptied. Also when we empty ispirto into the beaker from graduated cylinder, there are some ispirto left in the graduated cylinder. Ispirto evaporates fast, so the amount of ispirto decreases in every second. Transferring ispirto from graduated cylinder to beaker made the experiment harder to be more precise on the volume. The set-up of the experiment took 5 minutes and trials took maximum of 4 minutes each.
IMPROVING THE INVESTIGATION
The beam balance should be oiled really well in order to decrease the friction to minimum and the results will be more precise and this will also decrease the systematic errors. If we were using one beaker the amount of lost ispirto during transferring would be decreased, so the results would be more accurate. If we have an eyedropper we can be more precise about the value on the graduated cylinder. Instead of looking the value on the graduated cylinder with eye, a laser pointer could be used. In order to decrease the effect of random errors more number of trials should be made. There could be a time limit for each trial, so the amount of ispirto lost into air would be less.
