J.R. S. answered • 07/07/18
Tutor
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Ph.D. in Biochemistry--University Professor--Chemistry Tutor
What is 6/55 M supposed to mean?
The reaction of NaOH and H2SO4 is as follows:
2NaOH + H2SO4 ==> Na2SO4 + 2H2O
Note it takes 2 moles NaOH for each mole of H2SO4
How many moles of NaOH are present? 0.04 L x 0.1 mole/L = 0.004 moles NaOH present.
Thus, one needs 0.004/2 moles of H2SO4 to completely neutralize the NaOH = 0.002 moles H2SO4
The volume of H2SO4 needed for this is (xL)(0.2 mole/L) = 0.002 moles and x = 0.01 L = 10 ml H2SO4
Now, if we knew what 6/55 M meant, we could continue the calculations to find how much additional H2SO4 was required in that additional total volume (now 50 ml) to produce such a final concentration. This would be accomplished by M1V1 = M2V2.
J.R. S.
tutor
I can explain in full if you tell me what is meant by 6/55 M. That value makes no sense to me.
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07/07/18
Prakhar S.
after mixing the concentration of H2So4 becomes 6/55 M
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07/10/18
J.R. S.
tutor
I still don't understand what 6/55 M is supposed to mean. We usually express concentration as 1 M, 0.5 M, 2.5 M, 0.1 M, etc., etc. I've never seen anything like 6/55 M. Is that supposed to be 6 divided by 55 or 0.109 M?
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07/10/18
Prakhar S.
yes it means 6 divided by 55 i.e 0.109
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07/13/18
J.R. S.
tutor
If it means 6/55 = 0.109 M, then according to my original post, and the balanced equation, it will take 10 ml of the H2SO4 to just completely neutralize the NaOH, at which point there will be no H2SO4 and no NaOH. The only thing present will be H2O and Na2SO4. Now, to get a H2SO4 concentration of 0.109 M, we can calculate volume of 0.2 M H2SO4 needed. We already have 50 ml (10 ml acid + 40 ml base) = 0.05 L of solution. Using V1M1 = V2M2 one can find final volume of solution required.
(x L))(0.2 mol/L) = (0.05 L + x L)(0.109 mol/L)
0.2x = 0.00545 + 0.109x
0.091x = 0.00545
x = 0.0599 L = 59.9 ml as a final volume
The volume already was 50 ml (10 ml acid + 40 ml base), so one would need an additional 9.9 ml of acid. Thus, one should add 19.9 ml of 0.2 M H2SO4 to 40 ml of 0.1 M NaOH to obtain the desired molarity of H2SO4.
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07/13/18
Prakhar S.
let it be sir thanks for your time
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07/13/18
Prakhar S.
07/07/18