In this experiment, I am going to test the factors which affect the rate of evaporation for a liquid. The liquid that shall be used in this case is water. This is because it is cheap, easily available and not harmful as it has a PH7 (it is neither an acidic or an alkaline substance). The whole class will do one experiment between two, meaning that there will be two results for the temperatures between 30^oc and 80^oc (graduated in 10^oc

I think, that the more heat given to the water, the faster it will evaporate. This is because heat gives energy and the more energy the particles have, the quicker they will move to the surface, and evaporate.

Tripod, gauze, 250^cm3 beaker containing 150^cm3 of water, heat proof mat, glass rod (for stirring), Bunsen burner, thermometer (range –10^oc, 110^oc graduated in 1^oc), weighing machine (reads to 2 decimal places (2d.p.)).

In order to ensure that this experiment is a fair one, the following factors will be kept equal throughout the experiment and will be the same for all the experiments carried out: The surface area of the liquid, the liquid used, the size of the experiment, the amount of liquid (water), the time allowed for the water to boil.

The only risk that has to be taken into account is that a Bunsen burner has to be put on a fire proof surface (ie. A heat proof mat) to avoid danger. We use water because it has a pH 7 and is therefore not dangerous (it’s neutral). Safety goggles should also be worn in any experiment to avoid danger.

The results will be written up into a table which will later be converted into a graph. This will show mass of water evaporated (in grams) during the course of the experiment alongside the temperature it evaporated at. This reading will be taken by subtracting the final mass of the beaker and water form the original mass of the beaker and water. This will give the mass of water which was evaporated.

• The water in the beaker was then heated to a designated temperature, kept constant for two minutes and then weighed. A note of the weight was made correct to two decimal places. This is the original mass.
• The water contained in the beaker was kept at the temperature it was originally heated to for a period of time.

• The beaker containing water was then re-weighed and again, a reading will be given correct to two decimal places. This is the final mass.

To calculate the mass of water evaporated during the experiment (see graph above), the final mass was subtracted from the original mass to give a sum in grams. This is how much water was evaporated for each temperature during each experiment.

The higher the temperature the water was heated at, the quicker the particles moved to the surface and the quicker the water evaporated.

This is because when you give something energy (such as heat energy), the particles within it begin to move, the more energy is given, the quicker the particles move to the surface of the liquid and evaporate.

My prediction was correct. The higher the temperature, the more liquid was evaporated. This is because the heat made the particles move to the surface faster so they could evaporate.

The conclusion is confirmed by looking at the results (except for the 70^oc reading which is anomalous). The higher the temperature the liquid (water) was heated to, the more mass of water was evaporated.

In order to fully examine this theory, further work could be done using temperatures which are either very high or very low. Also, other factors could be tested instead of temperature, such as surface area, amount of liquid and so forth.

As the surface area of the liquid increases, so does the rate of evaporation. This is because the greater the surface area, the more particles there are to evaporate.

50^cm3 of water was measured out using a 100cm3 measuring cylinder into each of four different sized beakers (400cm3, 250cm3, 150cm3 and 75cm3). Each beaker was then weighed and the masses were recorded. The beakers were then left in the laboratory for one week for one week before being re-weighed.

The only variable in this experiment is the size of the beaker and therefore the surface area of the water exposed to the air, everything else must be constant (or at least the same for all the beakers). Ie. The amount (volume) of water in the beaker, the temperature of the beakers, and how long the beakers are to be left out for (the time given for the water to evaporate).

Whenever an experiment involves making a measurement using a measuring cylinder or a thermometer etc. We have to make a judgement in order to take the reading. Even using the apparatus as accurately as possible different people will read a value slightly differently, usually maybe half a degree or half a cubic centimeter around the correct value. NB. This isn’t the same as making a mistake and simply reading the scale wrongly.

This experiment error needs to be identified so that we know how reliable our experimental conclusions can be. These Measurement areas can either give an answer which is too high or too low because when we judge the value, different people will read either too high or too low. Therefor the error is Random.