Answer to Question #86230 in Organic Chemistry for john

Question

A buffer solution is prepared by mixing 100.0mL of 1.0M lactic acid with 100.0mL of 1.0M sodium lactate.

Calculate the volume (in mL) of 2.0M HCl required to change pH of 50.0mL of this buffer by one pH unit. Ka (lactic acid) = 1.38x10^-4

Answer 1

Step 1

Lets determine the pH of first buffer lactic acid/lactate

Step 2

The pH₂ what we are need to achieve is one point less than pH₁.

It means pH₂= 2.86.

Lets determine concentration of H⁺ ions in our second solution 

Step 3

As we now that we are taking only 50ml of the first 1M buffer solution than we need to calculate how many H⁺ ions will react with conjugation with HCL 

Step 4

Now we calculating the volume of HCL which we used.

We need to create equation

125ml of HCL