Hacettepe University Department of Chemical Engineering
KMÜ 210/21 – Chemical Engineering Thermodynamics
Prof. Dr. Tülay Durusoy
HOMEWORK 1 (Due March 4, 2015)
1. “SVA” Problem 1.4: At what absolute temperature do the Celsius and Fahrenheit
temperature scales give the same numerical value? What is the value?
2. “SVA” Problem 1.7: The reading on a mercury manometer at 25 oC (open to the
atmosphere at one end) is 56.38 cm. The local acceleration of gravity is 9.832 m s-2.
Atmospheric pressure is 101.78 kPa. What is the absolute pressure in kPa being
measured? The density of mercury at 25 oC is 13.534 g cm-3.
3. “SVA” Problem 1.15: A gas is confined in a 1.25 ft diameter cylinder by a piston,
on which rests a weight. The mass of a piston and weight together is 250 lbm. The
local acceleration of gravity is 32.169 ft s-2, and atmospheric pressure is 30.12 in
Hg.
a) What is the force in lbf exerted on the gas by the atmosphere, the piston, and the
weight, assuming no friction between the piston and cylinder?
b) What is the pressure of the gas in psia?
c) If the gas in the cylinder is heated, it expands, pushing the piston and weight
upward. If the piston and weight are raised 1.7 ft, what is the work done by the
gas in (ft lbf)? What is the change in potential energy of the piston and weight?
4. “SVA” Problem 1.18: An automobile having a mass of 1250 kg is traveling at 40 m
s-1. What is its kinetic energy in kJ? How much work must be done to bring it to a
stop?
5. “SVA” Problem 2.18: Liquid water at 180oC and 1002.7 kPa has an internal energy
of 762.0 kJ kg-1 and a specific volume of 1.128 cm3 g-1.
a) What is its enthalpy?
b) The water is brought to the vapor state at 300oC and 1500 kPa, where its
internal energy is 2784.4 kJ kg-1 and its specific volume is 169.7 cm3 g-1.
Calculate U and H for the process.
6. “SVA” Problem 2.36: One kilogram of air is heated reversibly at constant pressure
from an initial state of 300 K and 1 bar until its volume triples. Calculate W, Q, U
and H for the process. Assume for air PV/T=83.14 bar cm3 mol-1 K-1 and
Cp=29
Jmol-1K-1.
7. H2O is contained in a frictionless piston/cylinder device. Initially, the piston lies on
the lower stops, and the properties of H2O are given as: pressure (P1) and volume
(V1). The system has a slow heat transfer with the surroundings and the piston
starts floating when the pressure becomes (2P1). The process is stopped, when the
pressure becomes (3P1).
a) Show the process path on a p-V diagram. Explain briefly.
b) Find the work done by H2O during this process.
8. A rigid insulated tank is separated into two rooms by a stiff plate. Room A of 0.5 m 3
contains air at 250 kPa, 300 K and room B of 1 m3 has air at 150 kPa, 1000 K. The
plate is removed and the air comes to a uniform state without any heat transfer.
Find the final pressure and temperature.