equivalence point

[vcuchic]

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hey guys,

I need help on this gen chem question from Top Score..

Question:
In order to reach the equivalence point, what volume of a 5M NaOH solution is needed to titrate 0.25L of a 4M solution of HCL?

Answer:
0.2 L

Explanation:
5V = 0.25L (4)
V = 0.2 L


I don't get why the equation is the way it is...because it makes more sense (to me) to set up the equation as
5V = 4 (0.25 + V)

Because don't we have to consider the .25L that is already in the solution plus the remaining solution of NaOH we have yet to put in?
For the other titration questions (that don't include anything about equivalence points), I use this method and it works out well..

Any help is greatly appreciated.
Thank you!

 

[whoaaitzkyle]

hey guys,

I need help on this gen chem question from Top Score..

Question:
In order to reach the equivalence point, what volume of a 5M NaOH solution is needed to titrate 0.25L of a 4M solution of HCL?

Answer:
0.2 L

Explanation:
5V = 0.25L (4)
V = 0.2 L


I don't get why the equation is the way it is...because it makes more sense (to me) to set up the equation as
5V = 4 (0.25 + V)

Because don't we have to consider the .25L that is already in the solution plus the remaining solution of NaOH we have yet to put in?
For the other titration questions (that don't include anything about equivalence points), I use this method and it works out well..

Any help is greatly appreciated.
Thank you!

For any titration of neutralization questions you want to use the formula N1V1=N2V2. N=normality and V=volume. I am not familiar with your other method but this one is very simple and hopefully more straightforward!

 

[D D S 2 B]

Yes use n1v1=n2v2 and its straigh up plug in after that...try the destroyer it will help with the sciences a lot, and explains how to approach all these types of problems

 

[vcuchic]

oh thanks!

So is normality always the same as molarity?

 

[D D S 2 B]

oh thanks!

So is normality always the same as molarity?

No Normality is Always greater then or equal to molarity...

 

[IsRaEl21]

Basically normality is used in titration or nutralization. Normality refers to the number of acidic H or basic OH. Lets say M H2S04 is 2 M the normality is = to 4 N since we have 2 acidic protons of H. Or if the N of Ca(OH)2 is 4 N the Molarity is 4/2 = 2 M sice we have 2 OH groups. Therefore, as D D S 2 B said Normality is either equal or grater than Molarity. Read the Destroyer it's just amazing how it explained there. Really hope I helped u. Good Luck!!!

 

[whoaaitzkyle]

oh thanks!

So is normality always the same as molarity?

I like to think of everything in some form of an equation.

Normality= Molarity x i

i=dissociated particles.

So if you have H2SO4, 2H+'s will dissociate and if it's in a 1M solution then you know the normality is 2.

 

[vcuchic]

oohh gotcha.
easy stuff once someone explains it to you in baby words haha
thanks a lot guys