# Chemistry buffers

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#1

For questions like this, is this theory right?

So if you add salt to an acid, you’ll just sub the concentration into the equation to find out the concentration of H^+ ions

If it’s acid add base (NaOH) - mole of acid take away mole of base before subbing calculated concentration into the equation

If it’s acid, base and salt mixed together- let’s say base =5moles
Mole of acid -5
Calculate conc and sub into equation

Mole of salt +5
Calc concentration and sub into the equation ?
0
2 months ago
#2
(Original post by Yazomi)

For questions like this, is this theory right?

So if you add salt to an acid, you’ll just sub the concentration into the equation to find out the concentration of H^+ ions

If it’s acid add base (NaOH) - mole of acid take away mole of base before subbing calculated concentration into the equation

If it’s acid, base and salt mixed together- let’s say base =5moles
Mole of acid -5
Calculate conc and sub into equation

Mole of salt +5
Calc concentration and sub into the equation ?
not sure what you mean but to calculate pH of a buffer, you will need to use the Ka equation to find out [H+]. This involves finding the conc of the acid, the conc of the salt added, rearranged to solve for [H+], and subbing it into pH equation.
Last edited by CJField; 2 months ago
0
2 months ago
#3
you will need to use the Ka formula for dissociation of methanoic acid which is:
Ka = [HCOO-][H+] / [HCOOH]
sodium methanoate dissociates into Na+ and HCOO- so the [HCOO-] is equal to the conc of sodium methanoate
use the Ka value given, the conc of sodium methanoate and methanoic acid to sub back into the Ka equation to work out [H+], which you can then use to work out pH
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