Question

You will use a small, stoppered Erlenmeyer flask when determining the density of your unknown. Which statement best explains why the flask is stoppered?

		to prevent spillage
		to prevent evaporation
		to prevent odors from smelling up the lab
		to keep the volume of the flask constant

Answer 1

D = M/V______this is the equation for calculatio of density of unknown liduid.

where D = density, M = mass and V = volume to calculate the density of the unknown liquid.

We can obesereve from above equation that density is defends upon mass and the volume of the solution. Therefore, Density Measurment flask is stoppereds because while measurement evaporation should be avoided and the volumen of the bottle should be kept constant. If bottle kept open and the solven from the bottles evaporates concentration of the soltion will vary slightly depending upon the rate of evaporation and the density mesurement will not be accurate.

Hence the correct answer would be to prevent evaporation and to keep the volume of the flask conastant.