There are 0.0039 mol of
Step 1. Calculate
Step 2. Calculate the initial value of
We don’t know the initial value of
Let's call it
In this case, we know the equilibrium value of
The equilibrium constant expression is
Step 3. Calculate the initial moles of
Here's another way which is related to maths and not chemistry
When we solve for pH we solve like this
Please notice in the calculation I changed pH to 2.63
This is because when I used all the variables including
Solve for b
Let's solve your equation step-by-step.
: Divide both sides by -1.
: Solve Logarithm.
10log(b)=10−2.636(Take exponent of both sides)
Solve Square Root.
(Divide both sides by 0.00068)
Now I think you know what to do