How to Prepare 0.1 M Tris-HCl Buffer: Step-by-Step Guide for Chem Gurus

[drunkenfool]

Would appreciate some assistance from some chem gurus

Trying to make the calculations necessary to prepare 0.1 M Tris-HCl buffer. I have 80mL of a 0.1 M tris solution and need to find the volume of 1 N HCl required to adjust the pH of Tris to 8.0. I believe I need to use the Henderson-Hasselbach equation but not sure how to set it up.

Thank you!

 

[Borek]

Check this out:

http://www.chembuddy.com?left=pH-calculation&right=pH-buffers-henderson-hasselbalch

and this

http://www.chembuddy.com?left=pH-calculation-questions&right=pH-buffer-q2

 

[ravenprp]

As a chemist, I am happy to assist you in preparing a 0.1 M Tris-HCl buffer. Here is a step-by-step guide to help you with the calculations:

Step 1: Determine the molecular weight of Tris and HCl

Tris (Tris(hydroxymethyl)aminomethane) has a molecular weight of 121.14 g/mol. HCl has a molecular weight of 36.46 g/mol.

Step 2: Calculate the moles of Tris needed

Since you have 80mL of a 0.1 M Tris solution, you have 0.1 moles of Tris in 80mL. To calculate the moles, use the formula: moles = molarity x volume (in liters). Therefore, 0.1 moles = 0.1 M x 0.08 L.

Step 3: Calculate the volume of HCl needed

To adjust the pH of Tris to 8.0, you will need to add a specific volume of 1 N HCl. To calculate the volume, use the formula: volume = moles/concentration. In this case, the concentration is 1 N, so the volume of HCl needed is 0.1 moles/1 N = 0.1 L or 100 mL.

Step 4: Calculate the final volume of the buffer

To make a 0.1 M Tris-HCl buffer, you will need to add the 80mL of Tris solution and the 100mL of HCl solution. The final volume of the buffer will be 180mL.

Step 5: Adjust pH using Henderson-Hasselbach equation

The Henderson-Hasselbach equation is pH = pKa + log([base]/[acid]). In this case, Tris acts as a base and HCl acts as an acid. The pKa of Tris is 8.06. Therefore, pH = 8.06 + log([0.1 moles]/[0.1 moles]) = 8.06 + log(1) = 8.06. This means that the pH of the buffer will be 8.06.

I hope this guide helps you in preparing your 0.1 M Tris-HCl buffer. If you have any further questions, please do not hesitate to ask. Happy experimenting!