Question

solid aluminum reacts with aqueous H2SO4 to form H2 gas and aluminum sulfate. when a sample of Al is allowed to react, 415mL of gas is collected over water at 23°C at a pressure of 755mmHg. At 23°C the vapor pressure of water is 21mmHg. What is the pressure in mmHg of the dry H2 gas?

Answer 1

The pressure of dry hydrogen gas is 734 mm Hg.And number of moles of hydrogen gas is 0.017mol.

Reacted mass of aluminium is 0.306 g.

Step-by-step explanation:

The total pressure is the sum of the individual pressure.

`P_(total)=P_{H_(2)}-P_{H_(2)O}`

Total pressure = 755 mmHg

Pressure of water = 21mmHg

`P_(total)=755-21= 734mmHg`

Therefore, The pressure of dry hydrogen gas is 734 mm Hg.

Number of moles of hydrogen gas can be calculate is as follows.

`n=(PV)/(RT)`

From the given,

Pressure "P" = 755 mmHg = 0.993 atm

Volume"V"= 415 mL = 0.415 L

Gas constant "R" = 0.0821 L.atm/mol.K

Temperature = 23+273= 296 K

`n=(0.993* 0.415)/(0.0821* 296)=0.017mol`

Therefore, number of moles of hydrogen gas is 0.017mol.

Mass of aluminium reacted:

`0.017mol* (2 molAl)/(3molH_(2))* (26.98Al)/(molAl)=0.306gAl`

Therefore, Reacted mass of aluminium is 0.306 g.