Question

part a

what is the molality of 3.00 g H2O2 in 97.00g of water?

part b

for the following reaction:

2NO(g)+2H2(g)-->N2 (g)+ 2H2O(g)

if N2 is being produced at rate of 0.25 atm/min, at which rate is NO being used up?

part c

what will be the total pressure in a 3.00 L vessel containing 7.80 mol N2, 2.10 mol O2, and 0.10 Ar at 0.00 degree celsius?

part d

at standard temperature, a closed container of dry air contains 159.6 torr O2, 76.0 torr Ar, and 592.8 torr N2, what is the mole fraction of oxygen?

part e

the rate constant for the radioactive decay of 239Pu is 2.88*10^-5 yr^-1. what is the halflife of this isotope of plutonium?

part f

the vapor pressure of pure water is 17.54 torr at 20 degree celsius. what is the vapor pressure of water in a solution containing a mole fraction X=0.75 of a nonvolatile solute?

Answer 1

part a

moles of H2O2 = 3.00 / 34

                        = 0.0882

molality = 0.0882 / 0.097 = 0.910

molality = 0.910 m

part b

2NO(g)+2H2(g)-->N2 (g)+ 2H2O(g)

rate = 1/2 d[NO]/dt = d [N2]/ dt

d[NO]/dt = 2 x 0.25 = 0.50 atm/min

d[NO]/dt = 0.50 atm/min

part c

total moles = 7.80 + 2.10 + 0.10 = 10

temperature = 273 K

volume = 3.00 L

P V = n R T

P x 3 = 10 x 0.0821 x 273

P = 74.7 atm

total pressure = 74.7 atm