a 5.000ml aqueous sample containing hydrogen peroxide as diluted to 25ml and analyzed by titration with permanganate.
2MnO4- + 5H2O + 6H+ --> 5O2 + 2Mn^2+ + 8H2O
The sample required 42.8 mL of 0.0175 M permangante to reach the end point. What is the concentration of H2O2 in the original sample?
so,i was trying to do M1V1 = M2V2 but I don't know the volume I would use for the hydrogen peroxide? Or is using that equation wrong...?
I think that using the equation is wrong, but im not 100 percent sure myself i mean im just trying to help as many ppl as i can
Nevermind - I think I see what I did wrong. I was using 25 mL as my volume for hydrogen peroxide, when I should have been using 20 mL since that was the volume being added. Though I don't necessarily understand how that's the volume that needs to be used.
To find the concentration of hydrogen peroxide (H2O2) in the original sample, you can indeed use the formula M1V1 = M2V2, which is the dilution equation.
In this equation, M1 represents the initial concentration of the substance, V1 is the initial volume of the substance, M2 is the final concentration, and V2 is the final volume.
In this case, M2 and V2 correspond to the concentration and volume of the permanganate solution, respectively, at the point of reaching the end point during titration.
Therefore, we need to find the values of M1 (concentration of H2O2) and V1 (initial volume of the H2O2 solution).
To get V1, we know that the original sample volume was 5.000 ml and it was diluted to 25 ml before the titration.
Now, let's solve for V1:
V1 = (V2 * M2) / M1
V1 = (42.8 ml * 0.0175 M) / M1
To proceed, we need to know the stoichiometry between permanganate (MnO4-) and hydrogen peroxide (H2O2). According to the balanced equation you provided, 2 moles of permanganate react with 5 moles of hydrogen peroxide.
So, the mole ratio of MnO4- to H2O2 is 2:5.
Using this information, we can write another equation:
V1 * M1 = V2 * M2 * (2/5)
Substituting the known values:
(42.8 ml * 0.0175 M) = (25 ml) * (0.0175 M) * (2/5)
Now, we can solve for M1 (the concentration of H2O2):
M1 = [(25 ml) * (0.0175 M) * (2/5)] / (42.8 ml)
M1 ≈ 0.018 M
So, the concentration of hydrogen peroxide in the original sample is approximately 0.018 M.