Question

In a buffer solution the ratio of concentration of nh4cl and nh4oh is 1:1 when it changes in 2:1 what will value of ph of buffer

Answer 1

Ratio of Salt/Base = 1/1

Using teh formula,  

pOH = pKb + log[Salt]/[Base]

∴ pOH = pKb + 0

∴ pOH = pKb

Now, when [Salt]/[Base]  = 2/1

Then,

pOH₁ = pKb + log[2/1]

pOH = pKb + log[2]

∴ pOH₂ = pKb + 0.3010

∴ Subtracting second from 1.

∴ pOH₁ - pOH₂ = -0.3010

∴ pOH₂ - pOH₁ = 0.3010

Now, We must be having the pH value of first solution, then we can calculate pOH of other solution, After which,

pH + pOH = 14,

By using this formula we can calculate pH vale.

But your question is incomplete. You must have given this value of pH.

But all right, method is correct follow this.

Hope it helps.

Answer 2

or simply take ratio and subtract from 14