Question

On your first day working in a laboratory, you are told to make up 1 Liter of a 0.5 Molar Tris solution with a pH of 7.4. You measure out the appropriate amount of Tris base and dissolve it in water. You then measure the pH and find out that it has an initial pH of 11. You add some concentrated HCl, and the pH begins to drop. However, as you approach the target pH, you find that you need to add large amounts of HCl to lower the pH even a small amount.

Answer 1

Buffer solutions consists of weak acids and weak bases. The buffers are water based liquids and their ph must be near to acidic pH. Tris is used in DNA expractiomn process.

Tris Base has a Tris has a pKa of 8.1 and a pH level between 7 and 9.

materials required:

• tris(hydroxymethyl) aminomethane
• distilled deionized water
• HCl

1. we need to prepare 0.5M Tris, so calculate the amount of tris is used for the preparation of buffer.

formula: grams of Tris = (moles) x (121.14 g/mol)

0.5 x 121.14 = 60.57gm

Weigh 60.57gm of Tris and added to 1/3 of water and go for pH

If the pH is 11 then add some HCL into that when the pH came to required pH then add remaining water.

For reducing the amount of HCl to be added to the buffer then take the some high concentration of HCl insted small.