Question

In the followinmg question, absolute uncertainties for mass, volume, and density must be included. Show units for each value.

A student uses one of our 10mL pipettes to weigh out a known volume of liquid into a small beaker. Using the top loading balance, the beaker weighed 9.2g and 19.4g when empty and filled.

a) What is the mass of the liquid? _____+-______

b) What is the volume of the liquid? _____ +-______

c) What is the density of the liquid? ______ +- ______

Answer 1

Note: Since, the uncertainities in each value is not provided I am assuming 0.1 g or 0.1 ml

a)

Mass of empty beaker = 9.2 g ± 0.1 g

Mass of beaker with liquid = empty beaker + liquid = 19.4 g ± 0.1 g

Therefore,

Mass of liquid = (19.4 ± 0.1 g) - (9.2 g ± 0.1 g) = (19.4 - 9.2) ± (0.1 + 0.1 ) g = 10.2 ± 0.2 g

Answer: 10.2 g ± 0.2 g

b)

Volume of the liquid = 10 ml ± 0.1 ml

c)

Density of the liquid = mass / volume

= (10.2 ± 0.2 g) / (10 ± 0.1 ml)

= (10.2 / 10 ) ± ( 1.02 + 2.) % ( since, 10.2 * 0.1 = 1.02 and 10*0.2 = 2.0)

= 1.02 ± 3.02 % g/ml

= 1.02 ± 0.0302 g/ml

Therefore,

answer: density of the liquid = 1.02 ± 0.0302 g/ml