Question

Part A) A gaseous mixture contains 418.0 Torr of H2(g), 328.7 Torr of N2(g), and 79.9 Torr of Ar(g). Calculate the mole fraction, X, of each of these gases. XH2=. XN2=. XAr=

Part B) A 0.246 gram sample of a metal, M, reacts completely with sulfuric acid according to: M(s)+ H2SO4(aq) --> MSO4 (aq) + H2(g)

A volume of 257 mL of hydrogen is collected over water; the water level in the collecting vessel is the same as the outside level. Atmospheric pressure is 756.0 Torr and the temperature is 25 °C. The vapor pressure of water at various temperatures can be found in this table. Calculate the molar mass of the metal.

Answer 1

PART A:

We can express the mole fraction Xi of an individual gas i in a mixture in terms of the components partial pressure Pi.

then

=0.505

=0.397

=0.096

Part B:

First you need to get the moles of H2 produced. For that subtract the vapour pressure of H20 at 25 deg C from the pressure of the gass 756.0 Torr - 23.8 = 732.2 Torr/760 =0.963 atm

Now use the ideal gas law to calculate mole of H2.

PV=nRT

0.963 atm * 0.257 L = n *0.0821Latm/molK*298K

Since the stoichiometry of the reaction is 1:1 we had in the same of of metal M(s)

So the molar mass of M is

=24.31 g/mol