Chemistry - Thermochemistry Question with Solution | TestHub
The enthalpies of neutralization of a weak acid HA and a weak acid HB by NaOH are -6900 cal/equivalent and -2900 cal/equivalent, respectively. When one equivalent of NaOH is added to a solution containing one equivalent of HA and one equivalent of HB, the enthalpy change was -3900 cal. If the base is distributed between HA and HB in the ratio 1 : x, the value of 'x' is
Answer:
Solution:
When 1 equivalent of NaOH is added, it distributes between HA and HB. Specifically, 1/(1+x) of the NaOH reacts with HA, and x/(1+x) reacts with HB.
Given the initial amounts, we can set up the equation:
6900/(1+x) + 2900x/(1+x) = 3900
To solve for x, multiply both sides by (1+x):
6900 + 2900x = 3900(1+x)
6900 + 2900x = 3900 + 3900x
Subtract 2900x from both sides:
6900 = 3900 + 1000x
Subtract 3900 from both sides:
3000 = 1000x
Divide by 1000:
x = 3
Thus, the answer is 3.
