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Chemistry 340 Physical Chemistry for Biochemists I
Spring 2012
HOMEWORK SET No. 1
This homework set is due on Wednesday, January 18, 2012
1. For O2 give (a) the molecular weight, (b) the molecular mass, (c) the relative molecular mass,
(d) the molar mass.
2. Calculate the mass in grams of (a) one atom of carbon, (b) one molecule of water.
3. (3 points) A solution of HCl in water is 12.0% HCl by mass. Find the mole fraction of HCl and
H2O in this solution.
4. Do these conversions (a) 5.5 m3 to cm3, (b) 1.0 Gpa to bar, (c) 1.0 Gpa to atm, (d) 1.5 g/cm3 to
kg/m3.
5. For 1 mol of N2 gas at 0.0 oC the following volumes are observed as a function of pressure:
P/atm
1.0000 3.0000 5.0000
3
V/cm
22405
7461.4 4473.1
Calculate and plot PV/nT vs. P for these three points and extrapolate to P = 0 to evaluate R.
6. A student attempts to combine Boyle’s law and Charles’ law as follows: “We have PV = K1
and V/T = K2. Equals multiplied by equals are equal; multiplication of one equation by the
other gives PV2/T = K1 K2. The product K1 K2 of two constants is a constant for a fixed maount
of ideal gas.” What is the fallacy in this reasoning?
7. Prove that the equation PV/T = C1 for m constant and V/m = C2 for T and P constant lead to
PV/mT = a constant.
8. A student decomposes KClO3 and collects 36.5 cm3 of O2 over water at 23oC. The laboratory
varometer reads 751 torr. The vapor pressure of water is 21.1 torr at 23oC. Find the volume the
dry oxygen would occupy at 0oC and 1.000 atm.
9. A certain mixture of He and Ne in a 356-cm3 bulb weighs 0.1480 g and is at 20oC and 748 torr.
Find the mass and mole fraction of He present.
10. Find the molar volume of an ideal gas at 20.0oC and 1.000 bar.
11. For an ideal gas: (a) sketch some isobars on a Vm-T diagram; (b) sketch some isochores on a PT diagram.
12. For each of the following pairs, state which species has the greater van der Waals , b: (a) He
or Ne?, (b) C2H6 or C3H6, (c) H2O or H2S?