Thermodynamics
Problem Set 2
Topic: Kinetic Molecular Theory
Expansion
1. The Humber Bridge in England has the world’s longest single span, 1410 m.
Calculate the change in length of the steel deck of the span when the
temperature increases from -5.0°C to 18.0°C.
2. The outer diameter of a glass jar and the inner diameter of its iron lid are
both 725 mm at room temperature 20.0°C. What will be the size of the
difference in these diameters if the lid is briefly held under hot water until its
temperature rises to 50.0°C without changing the temperature of the glass?
3. (a) A wire that is 1.50 m long at 20.0°C is found to increase in length by
1.90 cm when warmed to 420.0°C. Compute its average coefficient of linear
expansion for this temperature range.
(b) The wire is stretched just taut (zero tension) at 420.0°C. Find the stress in
the wire if it is cooled to 20.0°C without being allowed to contract. Young’s
modulus for the wire is 2.0 x 1 011 Pa.
Gas Laws
1. The volume of a gas collected when the temperature is 11.0C and the
pressure is 710 mm Hg measures 14.8 mL. What is the calculated volume of
the gas at 20.0C and 740 mm Hg?
2. A 1.00 L sample of a gas has a mass of 1.92 g at STP. What is the molar mass
of the gas?
3. A sample of oxygen occupies 560. mL when the pressure is 800.00 mm Hg.
At constant temperature, what volume does the gas occupy when the
pressure decreases to 700.0 mm Hg?
Kinetic Theory
1. What is the average kinetic energy of a molecule of oxygen a temperature of
300K?
2. Superman leaps in front of Lois Lane to save her from a volley of bullets.
In a 1- minute interval , an automatic weapon fires 150 bullets , each of mass
8.0 g, at 400 m/s. The bullets strike his mighty chest , which has an area
of 0.75 m2. Find the average force exerted on Superman’s chest if the
bullets bounce back after an elastic , head-on collision.
