Question

Make sure that the following questions are answered in your submitted lab report. A student has an unknown liquid the theoretical density of which is 1.34 g/mL. He determines the experimental density of the liquid using the method described in the procedure for this experiment Tell whether each of the following errors would cause the experimental value of the density of the liquid to be too large, too small, or unchanged relative to the true value. Explain your reasoning in each case. a. The student blows out the last drop of liquid remaining in the pipet into the flask. b. When the student measures the liquid, the liquid level is slightly above the volume marking on the pipet. c. A piece of dirt sticks in the upper part of the pipet tip throughout the liquid measurements. d. A student uses a pipette that has not been dried and is contaminated with water.

Answer 1

To undesrtand the questions, I may remember the density formula.

$\small d=\frac{m}{V}$

In which:

d: density

m: mass

V: volume of solution

a)When he addds the last drop, it increases the volume of the solution and it decreases its density

b)When the student mesure the liquid volume over the volume making by the pipet, it increases the volume added to the flask causing that the density decreases.

c)A pipet of dirt sticks upper part of the pipet tip increases the volume measured on the pipet and decreased the volume added to the flask. It increases its density

d)If the volume is measured with a wet pipet, he adds an extra volume of water to the flask that increases its volume and decreases the density.