The standard deviation is determined by first calculating the mean, then taking the difference of each control result from the mean, squaring that difference, dividing by n-1, then taking the square root.
The higher the heat level is th â¦ e faster the liquids evaporate. But if you leave something outside like syrup for sometime, it will take much more longer to evaporate since syrup has a substance so much thicker than water.
Key Concepts. 1  Evaporation occurs when molecules in a liquid gain enough energy that they overcome attractions from other molecules and break away to become a gas. 2  Adding energy increases the rate of evaporation. 3  To conduct a valid experiment, variables need to be identified and controlled.