acid and bases q help
Original post by mohona1827
hey how do I do this q
It’s a standard weak acid calculation, but first, you need to work out the concentration of the weak acid after dilution.
Given that the original volume was 25.0 cm^3 (0.025 dm^3) and the original concentration was 0.50 mol dm^-3, can you calculate how many moles of the weak acid are in the solution?
When you dilute the solution, there is no change in the number of moles of weak acid. The only things that change are the volume of the solution and the concentration of the propanoic acid. The new volume is 100.0 cm^3 (0.1 dm^3). Can you now calculate the new concentration?
Now, you need to be able to write a Ka expression in terms of [H^+] and [CH3CH2COOH]. For a non-buffering weak acid solution, you can assume that [H^+] = [CH3CH2COO^-].
Rearrange your Ka expression and solve for [H^+]. You then use pH = -log[H^+] to find your final answer.
(edited 1 year ago)
Find the new concentration after dilution
To do that do the original concentration x ( original volume / new volume)
You should get 0.125 I think
H+ will then be the square root of ka multiplied by the concentration which is 0.125
Then just shove that in your calculator as -log(H+)
To do that do the original concentration x ( original volume / new volume)
You should get 0.125 I think
H+ will then be the square root of ka multiplied by the concentration which is 0.125
Then just shove that in your calculator as -log(H+)
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