Question

volatile liquid:
mass of flask, boiling stone, foil cap,
and unknown after cooling, g
mass of flask, boiling stone, and foil cap, g
water bath temperature, °c
barometric pressure, in. hg
volume of flask, ml
accepted molar mass of unknown, g mol⁻¹
(a) calculate the mass of the unknown.

Explanation:

Step1: Determine the mass of the unknown

The mass of the unknown can be found by subtracting the mass of the flask, boiling stone, and foil cap from the mass of the flask, boiling stone, foil cap, and unknown after cooling.
Let \(m_{total}\) be the mass of the flask, boiling stone, foil cap, and unknown after cooling (\(m_{total}=83.350\space g\)) and \(m_{flask + stone+cap}\) be the mass of the flask, boiling stone, and foil cap (\(m_{flask + stone+cap}=82.637\space g\)).
The formula for the mass of the unknown \(m\) is \(m = m_{total}-m_{flask + stone+cap}\)
Substitute the values: \(m=83.350 - 82.637\)

Answer:

\(0.713\space g\)