Question

Which of the following solutions would have the highest pH? Assume that they are all 0.10 M in acid at 25°C. The acid is followed by its Ka value.
a. HCHO2, 1.8 x 10-4
b. HF, 3.5 x 10-4
c. HClO2, 1.1 x 10-2
d. HCN, 4.9 x 10-10
e. HNO2, 4.6 x 10-4

Answer 1

Answer:

$HCN~~Ka=4.9x10^-^1^0$

Explanation:

In this case, we have to remember the relationship between the Ka value and the pH. We can use the general reaction for any acid with his Ka value expression:

$HA~->~H^+~+~A^-$    $Ka=\frac{[H^+][A^-]}{[HA]}$

In the Ka expression, we have a proportional relationship between Ka and the concentration of $H^+$. Therefore, if we have a higher Ka value we will have a smaller pH (lets keep in mind that with a higher

So, if we have to find the higher pH value we need to search the smaller Ka value in this case $HCN~~Ka=4.9x10^-^1^0$.

I hope helps!