Physical Chemistry Answers

What does it mean if the $\Delta H$ value for a chemical reaction is positive?

Calculate the total work done in the expansion of 2 moles of an ideal gas from an initial pressure of (4.0 x 10^5 Nm^-3) to a final pressure of (2.0 x 10^5 Nm^-3) at 298K. (R=8.314 J/K/mol)

One of these is correct about common-ion effect?
A. Promotes condensation
B. Promotes evaporation
C. Increases solubility
D. Reduces ionization

Air contains 20%by volume of oxygen. The volume of air required for the complete combustion of 1L of methane under the same conditions is

The process in which the solid directly evaporates without it melting is known as

One of these is correct about common-ion effect
a. promotes condensation
b. promotes evaporation
c. increase solubility
d. reduce ionization

Consider neon as ideal gas with a Maxwell distribution of speeds.
(a) For Ne at T = 300 K, obtain median speed vmed such that fractions of molecules with speeds above and under this value are equal. One way to do it is by trial-and-error calculations by adjusting vmed value (to accuracy of 1 m/s - your report must show this *).
(b) Compare (not just list, but say which is larger/smaller) vmed with vmp, 〈v〉, 〈v2〉1/2 for the same T.
(c) repeat part (a) for T = 600 K, and then for Ar at 300 K, and conclude how vmed changes relative to that in part (a) in each case.
(d) based on results above, conclude how exactly vmed depends on T and M, e.g. whether vmed is proportionate to T (or T1/2, or 1/T, or 1/T1/2), and similar for the dependence on M.

* for instance: at vmed, fraction (v>vmed) is larger than fraction(v<vmed),
and at vmed+1 m/s, fraction (v>vmed) is smaller than fraction(v<vmed)

Tractor exhaust has the following composition by volume at 38oC:
N2 = 73%, H2O = 13%, CO2 = 12%, O2 = 2%
find: apparent mol. weight, composition by weight, R for gas, volume of 1 kg mix.

N2 = 73%, H2O = 13%, CO2 = 12%, O2 = 2%.
find: apparent molecular weight, composition by weight, value of R for gas, volume of 1 kg mixture at 101 kPa.

Derive an expression for calculating energy values corresponding n = 3 for a particle in one dimensional box