# Molecular Weight Question

1. Mar 29, 2005

### MusicMonkey

What is the molecular weight of potassium phosphate buffer pH 6.8 and pH 6.4? I tried to find the answer but no luck. Please help calculate. Thank you.

2. Mar 29, 2005

### scarecrow

K+ PO3(4-) MW: 212.28 ...... am I missing something here? how does mw change as pH changes?

3. Mar 29, 2005

### Gokul43201

Staff Emeritus
It does not...and while you have the corrrect MW it looks like you may have mistyped the formula for $K_3PO_4$

4. Mar 30, 2005

### Staff: Mentor

Buffers are mixtures so there is no such thing as molar mass. Molar concentration of buffer refers to the total concentration of both acid and conjugated base.

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5. Mar 30, 2005

### scarecrow

yes, I realized that.