The Ka : 1.671 x 10⁻⁷
<h3>Further explanation</h3>
Given
Reaction
HA (aq) + H2O (l) ←→ A- (aq) + H3O+ (aq).
0.3 M HA
pH = 3.65
Required
Ka
Solution
pH = - log [H3O+]
![\tt [H_3O^+]=10^{-3.65}=2.239\times 10^{-4}](https://tex.z-dn.net/?f=%5Ctt%20%5BH_3O%5E%2B%5D%3D10%5E%7B-3.65%7D%3D2.239%5Ctimes%2010%5E%7B-4%7D)
ICE method :
HA (aq) ←→ A- (aq) + H3O+ (aq).
0.3 0 0
2.239.10⁻⁴ 2.239.10⁻⁴ 2.239.10⁻⁴
0.3-2.239.10⁻⁴ 2.239.10⁻⁴ 2.239.10⁻⁴
![\tt Ka=\dfrac{[H_3O^+][A^-]}{[HA]}\\\\Ka=\dfrac{(2.239.10^{-4}){^2}}{0.3-2.239.10^{-4}}\\\\Ka=1.671\times 10^{-7}](https://tex.z-dn.net/?f=%5Ctt%20Ka%3D%5Cdfrac%7B%5BH_3O%5E%2B%5D%5BA%5E-%5D%7D%7B%5BHA%5D%7D%5C%5C%5C%5CKa%3D%5Cdfrac%7B%282.239.10%5E%7B-4%7D%29%7B%5E2%7D%7D%7B0.3-2.239.10%5E%7B-4%7D%7D%5C%5C%5C%5CKa%3D1.671%5Ctimes%2010%5E%7B-7%7D)
Explanation:
The pressure exerted by vapors or gas on the surface of a liquid is known as vapor pressure.
This means that weaker is the intermolecular forces present in a substance more easily it can form vapors. As a result, it will have high vapor pressure.
As substance B has high vapor pressure which means that it has weak intermolecular forces.
Also, stronger is the intermolecular forces present in a substance more will be its boiling point. Hence, more energy or temperature is required to break the bonds. Hence, substance A has higher boiling point and high heat of vaporization.
When surrounding pressure is less than or equal to its vapor pressure then substance B boils into the gas phase. Hence, substance B will be a gas at 300 mm Hg.
Therefore, we can conclude that characteristics of the two substances will be as follows.
(a) Substance B - has weaker intermoclcular
(b) Substance A - has a higher boiling point
(c) Substance B - is a gas at 300 mm Hg
(d) Substance A - has a higher heat of vaporization
(3) nuclear fusion. Nuclear fusion reactions release a lot of energy
