(b) The student collects the H2(g) produced by the reaction and measures its volume over water at 298 K after carefully equalizing the water levels inside and outside the gas-collection tube, as shown in the diagram below. The volume is
measured to be 45.6 mL. The atmospheric pressure in the lab is measured as 765 torr, and the equilibrium vapor pressure
of water at 298 K is 24 torr,
45
46
Gas
Water
Calculate the following.
() The number of moles of h2 produced in the reaction

The pressure of  H₂(g) = 741 torr

Explanation:

Given that:

The atmospheric pressure measured in the lab  = 765 torr

The vapor pressure of water = 24 torr

By applying Dalton's Law of Partial Pressure :

Making The Pressure inside the tube due to the H₂(g) the subject of the formula :

we have:

= (765 -24) torr

= 741 torr

the ideal gas law equation is as follows

pv = nrt

where p - pressure

v - volume

n - number of moles

r - universal gas constant

t - temperature

so if the pressure, volume and temperature are already known

we are left with n and r

since r is the universal gas constant that has a known fixed value then r too is known

so we are left with 'n'

once we know temperature volume and pressure

we can find the number of moles of gas present using the ideal gas law equation

this is not my own answer, this is an answer for the same question by the user blahblahmali. i do not claim ownership of this account.

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