What Affects the Rate of Evaporation?
* To find out if changes in temperature, draught and surface area of water open to air affects the rate of evaporation through the water. * To safely check if these variables change the rate of evaporation * To complete all the experiments in the short period given Prediction
* I believe that a raise in temperature will speed up the rate of evaporation in the water * I believe that a larger surface area will speed up the rate of evaporation in the water * I believe that draught will not affect the rate of evaporation, or at least the rate at which it does affect evaporation will not be able to be measured in the short time available for each experiment Temperature
* Bunsen Burner
* Heat Mat
* Measuring Cylinder
* Safety Goggles
* In this experiment the control variables are the volume of water we use for each beaker. If we change the volume of water for each beaker, the results we get will not be relevant, since we are seeing what affects the rate of evaporation, and the more the volume of water, the slower the rate of evaporation. Therefore in this experiment, we are keeping the volume of water at 100ml. To do this well, we will use measuring cylinders to measure 100ml, then use the scales to make sure the same mass of water is used in each experiment. * Secondly, in this experiment, the size of the beaker must be kept the same because a bigger beaker can mean a larger surface area open to the air, and surface area 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.
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) 5) Take a measuring cylinder and fill water up to 100ml. In this experiment one of the control variables is the volume of water, because if the volume of water varies then the results will be not accurate and no conclusion can be drawn 6) When measuring 100ml, measure from the meniscus (lowest portion of the convex dip of liquid) 7) Measure 100ml of water, pour water into glass beaker, and repeat so that there are three beakers containing 100ml of water each. The beakers should be the same size, because we must control the surface are of water open to air in this experiment....
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