The hydrogen gas from the reaction of 1.0 g of iron with excess hydrochloric acid is collected in a 15.0 l flask at 25 degrees celsius. what is the pressure of the hydrogen gas in this flask?

P = 0.03 atm

Explanation:

Given data:

Mass of iron = 1.0 g

Volume of flask = 15.0 L

Temperature = 25 °C

Pressure of hydrogen gas = ?

Solution:

Chemical equation:

4HCl + 2Fe → 2FeCl₂ + 2H₂

Number of moles of iron:

Number of moles = mass/ molar mass

Number of moles = 1.0 g/ 55.85 g/mol

Number of moles = 0.02 mol

Now we will compare the moles of iron and hydrogen.

                Fe                :                H₂

                 2                 :                 2

               0.02              :              0.02

Pressure of hydrogen:

PV = nRT

P = nRT/V

P = 0.02 mol × 0.0821.atm.L/mol.K × 298 K / 15 L

P = 0.5 atm. L /15 L

P = 0.03 atm

the best answer is d because the strong cohesion is caused by the ability of water molecules to undergo hydrogen bonding.

a is incorrect because when water solidifies, it becomes   ice, which expands and occupies a bigger volume for the same mass of water in its liquid state.

b is incorrect because water has high surface tension. besides bonding to itself it hydrogen bonds to other molecules at the top decreasing possibility for breaking of attractive forces.

c is incorrect because the water molecule has oxygen which is highly electronegative and so pulls the electron pair towards itself creating a dipole moment, making the molecule polar.

e is incorrect because water has strong adhesion, ability to stick to other molecules such as glass because of this molecules having stronger hydrogen bonding than water.