The total volume of hydrogen gas needed to fill the hindenburg was 2.00 × 108 l at 1.00 atm and 25.° c. how much energy was evolved when it burned?

Answer : The energy evolved when it burned was,

Solution :

First we have to calculate the moles of hydrogen gas by using ideal gas equation.

where,

P = pressure of gas = 1 atm

V = volume of gas =

T = temperature of gas =

R = gas constant = 0.0821 Latm/moleK

n = number of moles of gas

Now put all the given values in the above formula, we get the moles of hydrogen gas.

Now we have to calculate the amount of energy evolved.

The combustion reaction of hydrogen will be,

The enthalpy of combustion of hydrogen is -286 KJ/mole. (standard value)

As 1 mole of hydrogen gas burned it evolved energy = -286 KJ

So, of hydrogen gas burned it evolved energy =

Therefore, the energy evolved when it burned was,

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.