What Affects the Rate of Evaporation in Different Liquids? Essay Example

could affect the rate of evaporation, meaning our results will be inaccurate. Therefore, for each test we checked that the beakers were all the same size using rulers. Thirdly time must be controlled in this experiment. If we change the amount of time heat is applied to the water, our results will not be relevant. The longer the heat is applied, the more water is evaporated (we predict) so therefore we must use a stop watch to try and keep the time that heat is applied to the water constant

Independent Variables

• In this experiment, the independent variable is the temperature of the water, since this is the thing which we are changing.

Therefore, to do this we will heat the water using a bunsen burner (with the air hole open different amounts), and use a thermometer to keep the water at the temperature we want.

Dependant Variable

Temperature Diagram

• The dependant variable is the amount of water that has evaporated (we later use this information to calculate the rate of evaporation). To measure this we will allow the water to cool after heating it (water expands when heated), then after cooling, either use a measuring cylinder or scales to check volume and mass before and after.

Method

• 1) First put on the safety goggles to protect against shattering glass
• 2) Put on the gloves since you are operating hot bunsen burners which may burn you, and you are carrying very hot beakers later on in the experiment
• 3) Connect the bunsen burner to the gas pipes and place the bunsen burner on top on a heat mat
• 4) Turn on the gas, close the air hole on
  

the bunsen burner so that a safety flame will appear, and get teacher to light bunsen burner (to avoid possible danger with fire)

ARE USING BUNSEN BURNERS AND HOT WATER SO MAKE SURE YOUR GLOVES AND GOGGLES ARE ON!!!

Results Temperature (oC)| Volume of Water (ml)| Mass of Water Before (g)| Mass of Water After (g)| Mass of Water Lost (g)| Rate of Evaporation (g/s)| 40. 0| 100| 98. 9| 97. 7| 1. 20| 0. 004| 60. 0| 100| 98. 9| 94. 9| 4. 00| 0. 013| 80. 0| 100| 98. 9| 93. 0| 5. 90| 0. 020| Graph Conclusion To calculate the rate of evaporation, I will use the equation “rate of evaporation=change in mass/change in time”. Therefore, the rates of evaporation for the different temperatures

are: * 40oC: Rate of evaporation=1. 2(g)/300(s)=0. 04g/s * 60oC: Rate of evaporation=4. 0(g)/300(s)=0. 013g/s * 80oC: Rate of evaporation=5. 9(g)/300(s)=0. 02g/s As we can see from the graph, and the results table, as we increase the temperature of the water, the mass of water lost through evaporation increases as well (as long as the water doesn’t boil (This does not show evaporation in the water)).

This means that temperature does affect the rate of evaporation, and that the higher the temperature of the water, the higher the rate of evaporation, meaning the higher the amount of water lost. This confirms my prediction.

The water evaporates because the heat from the bunsen burner causes the water to heat up (through conduction, convection and radiation) which gives the water molecules kinetic energy, causing them molecules to move more, until they break from the bonds holding them together and become a gas molecule. Evaluation I believe that in this experiment, the results were reliable and we should trust them. First of all, we recorded all of the results to three significant figures which is a good level of accuracy. There are no anomalies in our results for this experiment, mainly because we did the esults very carefully. However, our results may not be very reliable, because for each temperature we only performed the experiment once.

However, with the time constraints, we did as many experiments as possible. Also, our results were quite accurate since we used the scales to measure the masses of the water and the containers, and the scales were electronic so the results were to one decimal place. As well as this, since the scales were electronic,

the chance of human error is massively reduced so our results should be quite reliable.

• Evaporation dish Measuring Cylinder
• Water
• Safety Goggles
• Gloves
• Scales

Surface Area Equipment- Control Variables

• In this experiment, the main control variable is the amount of water we use. If the amount of water changes, then it would be difficult to compare results and our results would be useless. Therefore, we keep the amount of water the same by measuring the volume using measuring cylinders and measure the mass using scales to make sure both amounts of water have the same volume and mass.
• Also, we must control the temperature of both samples of water.

We know that temperature can affect the rate of evaporation, so the temperature must be the same in both samples; room temperature (roughly 20oC). We will do these using thermometers.

* Thirdly time must be controlled in this experiment. If we change the amount of time the water is left to evaporate, our results will not be relevant. The longer we leave the water, the more water is evaporated (we predict) so therefore we must use a stop watch to try and keep the time that the containers containing the water are left out constant Independent Variables In this experiment the independent variable is the surface area of water open to the air since that is the variable we change. In one experiment we will have a container with a very small surface area and in the other we will have a container with a large surface area.

Dependant Variable 

The dependant variable is the amount of water that has evaporated (we later use this information to calculate the

rate of evaporation). To measure this we will measure the volume and mass of water before and after evaporation has taken place and compare.

Surface Area Diagram Method

• 1) First put on the safety goggles to protect against shattering glass
• 2) Measure the mass of the evaporation dish and the measuring cylinder
• 3) Fill up the evaporation dish until it is full to the top (top is widest and easiest to work out diameter from)
• 4) Measure the amount of water the evaporation dish can hold using the measuring cylinder and measure how much this amount of water weighs (measuring cylinder+water-measuring cylinder)
• 5) Fill the evaporation dish again to the top again
• 6) Fill the measuring cylinder to the amount the evaporation dish can carry
• 7) Place them both carefully (DONT LET YOUR HAND SHAKE AND SPILL WATER) on a windowsill and start the stopwatch
• 8) After five minutes carefully take off the containers from the windowsill and measure the mass and volume of the water in the containers now using the scales and the measuring cylinder
• 9) If some water does spill, do not worry
• 10) Repeat the experiment for more reliable results Results Try One

Diameter Of Container (cm)| Surface Area Open to Air (cm2)| Volume of Water (ml)| Mass of Water Before (g)| Mass of Water After (g)| Mass of Water Lost (g)| Rate of Evaporation (g/s)| 3. 00| 28. 3| 114| 114. 3| 113. 7| 1. 20| 0. 004| 9. 00| 254| 114| 114. 3| 99. 8| 14. 5| 0. 048| Try Two Diameter Of Container (cm)| Surface Area Open to Air (cm2)| Volume of Water (ml)| Mass of Water Before (g)| Mass

of Water After (g)| Mass of Water Lost (g)| Rate of Evaporation (g/s)| 3. 00| 28. 3| 114| 114. 3| 114. 2| 0. 1| 0. 0003| 9. 00| 254| 114| 114. 3| 110. 0| 4. 3| 0. 014| Average

Diameter Of Container (cm)| Surface Area Open to Air (cm2)| Volume of Water (ml)| Mass of Water Before (g)| Mass of Water After (g)| Mass of Water Lost (g)| Rate of Evaporation (g/s)| 3. 00| 28. 3| 114| 114. 3| 113. 95| 0. 65| 0. 002| 9. 00| 254| 114| 114. 3| 104. 9| 9. 4| 0. 031| Graph Conclusion To calculate the rate of evaporation, I will use the equation “rate of evaporation=change in mass/change in time”. Therefore, the rates of evaporation for the different surface area are: * 28. 3cm3 Try One: Rate of evaporation=1. 2(g)/300(s)=0. 004g/s * 28. 3cm3 Try Two: Rate of evaporation=0. (g)/300(s)=0. 0003g/s * 28. 3cm3 Average: Rate of evaporation=0. 65(g)/300(s)=0. 002g/s * 254cm3 Try One: Rate of evaporation=14. 5(g)/300(s)=0. 048g/s * 254cm3 Try Two: Rate of evaporation=4. 3(g)/300(s)=0. 014g/s * 254cm3 Average: Rate of evaporation=9. 4(g)/300(s)=0. 031g/s In both the results and the graph we can see that the larger the surface area open to the air, the more water is lost through evaporation. Even though I believe that these results are completely false (which I will explain in the evaluation), these results do show that surface area affects the rate of evaporation.

The larger the surface area, the higher the rate of evaporation, meaning the higher the amount of water lost. This confirms my prediction. I believe that the water evaporated because when the surface area is bigger, there is

a larger area of water molecules open to the air and the air molecules collide with the molecules on the top of the water, giving them kinetic energy, allowing them to more faster and break away from the bond holding them together and become a gas. Evaluation I believe that in this experiment, the results were completely unreliable and should not be trusted.

While doing both of the experiments, I was constantly pushed (accidently) by people rushing around doing their experiment, causing water to spill out of the container. Since the evaporation dish was full to the top, more of the water spilt out of the evaporation dish than the measuring cylinder than the so that is why the results were as unexpected as they were. As well as this, there may have been an experimental error when measuring the mass of the water, since there were already traces of water on the scales from previous experiments.

Since the first set of unexpected results, I decided to adapt and do a second experiment, but again the same thing happened so overall, all of these results are worthless and no conclusion can be gained from them. To improve the results I should have repeated the test again, and try and be more careful, but with the time restraints, this was difficult. Also, our results should have been quite accurate, since we used the electronic scales, but unfortunately our results were incorrect.

1. Fan
2. Measuring Cylinder
3. Glass Beaker
4. Water
5. Safety Goggles
6. Gloves
7. Scales

Draught Equipment- Control Variables

• In this experiment, the main control variable is the amount of water we use. If the amount of water changes, then it would
  

be difficult to compare results and our results would be useless. Therefore, we keep the amount of water the same by measuring the volume using measuring cylinders and measure the mass using scales to make sure both amounts of water have the same volume and mass.

Therefore, for each test we checked that the beakers were all the same size using rulers.

Independent Variables

• In this experiment the independent variable is the draught of air acting on the water since that is the variable we change. In one experiment we will have a container with a fan blowing onto it, and in the other we will have a container with no (or as little as possible) draught acting on the water.

Dependant Variable

• Surface Area Diagram The dependant
  

variable is the amount of water that has evaporated (we later use this information to calculate the rate of evaporation).

To measure this we will measure the volume and mass of water before and after evaporation has taken place and compare.

Method

• First put on the safety goggles to protect against shattering glass
• Measure the mass of the measuring cylinder using the scales
• Use the measuring cylinder to measure 100ml of water, then pour into the glass beaker
• MAKE SURE ALL BEAKERS USED ARE THE SAME SIZE
• Measure the mass of the beaker and water together.
• Fill another beaker up with 100ml of water and make sure the mass of both beaker+water used are equal.
• Take one beaker and water and place it under a fan (moving at a high speed)
• Start the stopwatch
• Take one beaker and cover it from any draught, using your body as a shield.
• Start the second stopwatch
• After five minutes stop the stopwatch and take both beakers away from their locations so neither has any draught.
• SWITCH OFF FAN TO ENSURE NO ONE IS INJURED IN FAN RELATED ACCIDENT.
• Measure mass of the beaker+water again
• Repeat experiment for more reliable results Results

In both the results and the graph we can see that if a draught is applied, then slightly more water is lost through evaporation (0. 2g more). The means that if a draught is a applied to a volume of water, the higher the rate of evaporation, meaning the higher the amount of water is lost through evaporation. This is different from my prediction! This might be different to my prediction because I thought that temperature was the main way

to evaporate a body of water, and I thought that, by applying a draught, we are reducing the temperature of the water, causing it not to evaporate.

However, perhaps the fan gave kinetic energy to the molecules on the top of the water, causing them to move faster and eventually break away from the bonds holding them together and escape as a gas. Evaluation I believe that in this experiment, the results were reliable and we should trust them. First of all we recorded all of the results to three significant figures (where possible) which is a good level of accuracy. There are no anomalies in the experiment, only unexpected results, which I explained in the conclusion.

Our results could have been made slightly more reliable by performing the experiment a few more times, but with the limited time, this wasn’t an option. Also our results should be quite accurate since we used the scales to measure the masses of water and containers, and used a pipette to make sure the mass of water was equal to 100g in both containers (in this test we knew that if any water evaporated, it would be a very small amount). Also, since we used electronic scales, the chance of human error was reduced.