[aeacfm]

some takeaway problems make me confused too much .

simply , equivalent wt what i know is that eq = Mwt/n , n = no of euivalents

n depends on the reaction (acid base , redox , .)

1 - suppose for Na2Co3 how can i get the no equivalents (what i know is no of equivalents = no of gram equivalents) if no reaction deatiled and a weight value given x gram ?
n = wt/eqwt , eqwt = Mwt/2*1 is that right ?

2 - calculate the concentration of NaOH if 48.19 ml of 1.75 N H2SO4 neutralizes 25ml of the base ?
the answer was by :
N1 . V1 = N2 . V2

but if the context was 48.19ml of 1.75 M H2SO4 neutralizes 25ml of the base ?. the answer was by calculating the no of moles of the acid then calculating moles of base from ratio between acid and base in the equation !!!!

pls explain

[aeacfm]

aha m my language i a problem
simply i want to know how to calculate the no of gram equivalent wt in case of precipitation reactions and salts alone if no reactions given ?

[DevaDevil]

sodium carbonate is indeed 2-equivalent, as it can take up 2 protons to form water and carbon dioxide.

2. I assume you have 25ml of sodium carbonate at your given equivalent. Sulfuric acid is also 2-equivalent, which makes that calculation easier.
Or you can indeed calculate the number of moles of carbonate in the base, and number of moles of protons in the acid, and calculate what is left after the neutralization reaction.

[Nobby]

That is the question how something will react.

In case oft the CO₃^2- the equivalent is 1 in case of the Na⁺ its 2

But this is not a good example.

Lets have Chromate  CrO₄^2-

This can react with Barium to BaCrO₄

1 mol Ba²⁺ reacts with one mol CrO₄^2- to BaCrO₄


But if you use it as an oxidieser it reacts different. you get Chromium-III

2 CrO₄^2- +  3 SO₃^2- + 5 H₂O  => 2 Cr³⁺ + 10 OH^- + 3 SO₄^2-

1 Chromate is 1,5 equivalent to Sulfite.

[DevaDevil]

That is the question how something will react.

look at the second part: simple neutralization. Carbonate takes up 2 protons, hence 2-equivalent in this particular case.

[aeacfm]

thank you sir
that says when H2SO4 reacts with NaOH (complete reaction ) the no of equivalents is 2 but when reacts with BaCl2 (complete reaction ) so it gives only one equivalent ....is this right ?

[Nobby]

Yes you got it.

[aeacfm]

so for this reaction
3Zn++ + 2K+ + 2Fe(CN)6-4 ======>  Zn3K2[Fe(CN)6]2¯
no of euivalents of Zn = 2
but for Potassium ferrocyanide .

[Nobby]

1 Zinc is equal to 0.66 hexacyanoferrat

[aeacfm]

1 Zinc is equal to 0.66 hexacyanoferrat

not clear !!!!!!

[Nobby]

3 Zn²⁺ react with 2 [Fe(CN)₆]^4-

1 Zn²⁺ equal to 2/3 = 0,66 [Fe(CN)₆]^4-

or you can say 1 [Fe(CN)₆]^4- equal to 1.5 Zn²⁺