The answer is (3) 11.2 L of N2(g). When the choices are all gases, the number of molecules depends on the molar number of the gas. Under the condition of STP, the molar number of a gas is depends on volume only. So the same volume of gas has the same number of molecules.
Given:
Diprotic weak acid H2A:
Ka1 = 3.2 x 10^-6
Ka2 = 6.1 x 10^-9.
Concentration = 0.0650 m
Balanced chemical equation:
H2A ===> 2H+ + A2-
0.0650 0 0
-x 2x x
------------------------------
0.065 - x 2x x
ka1 = 3.2 x 10^-6 = [2x]^2 * [x] / (0.065 - x)
solve for x and determine the concentration at equilibrium.
You need 4 H2 molecules and 2 O2 molecules.
This is because water is H2O which is 2 Hydrogen and 1 Oxygen so if you want to make 4 water molecules, you’ll need 8 hydrogen and 4 oxygen.
Given H2 you need 4 because 4•2 is 8 and for O2 you need 2 because 2•2 is 4.
I hope this makes sense.
