Answer:
pH = 2.462.
Explanation:
Hello there!
In this case, according to the reaction between nitrous acid and potassium hydroxide:

It is possible to compute the moles of each reactant given their concentrations and volumes:

Thus, the resulting moles of nitrous acid after the reaction are:

So the resulting concentration considering the final volume (20.00mL+13.27mL) is:
![[HNO_2]=\frac{6.73x10^{-4}mol}{0.01327L+0.02000L} =0.02023M](https://tex.z-dn.net/?f=%5BHNO_2%5D%3D%5Cfrac%7B6.73x10%5E%7B-4%7Dmol%7D%7B0.01327L%2B0.02000L%7D%20%3D0.02023M)
In such a way, we can write the ionization of this weak acid to obtain:

So we can set up its equilibrium expression to obtain x as the concentration of H3O+:
![Ka=\frac{[NO_2^-][H_3O^+]}{[HNO_2]}\\\\7.1x10^{-4}=\frac{x^2}{0.02023M-x}](https://tex.z-dn.net/?f=Ka%3D%5Cfrac%7B%5BNO_2%5E-%5D%5BH_3O%5E%2B%5D%7D%7B%5BHNO_2%5D%7D%5C%5C%5C%5C7.1x10%5E%7B-4%7D%3D%5Cfrac%7Bx%5E2%7D%7B0.02023M-x%7D)
Next, by solving for the two roots of x, we get:

Whereas the correct value is 0.003451 M. Finally, we compute the resulting pH:

Best regards!
Explanation:
The group number in the periodic table represents number of valence electrons of the elements in a certain group.
Group 1 : 2,8,1
Group 2 : 2,8,8,2
Group 3 : 2,8,3
Group 4: 2,4
Group 7 : 2,8,7
Answer:
We are given:
V(i) = 0.3 L V(f) = 0.36 L
P(i) = x pa P(f) = 400 pa
T(i) = T(f) = 293 k
Using the gas formula:
PV = nRT
Since n , R and T are constant,
PV = k (where k is a constant)
Hence we can say that:
P(i) * V(i) = P(f) * V(f)
x * 0.3 = 0.36 * 400
x = 14.4/0.3
x = 480 pascals
Hence the initial pressure is 480 pascals
Converting to Kpa, we have to divide by 1000
Initial pressure (Kpa) = 0.48