GC question, need some advice.

[Cosmicnova]

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this following question from Kaplan GC workshop quiz.

What is the normality of a 1M solution of H3PO4 if titrated with CaCl2?

A. 0.5 N
B. 1.0 N
C. 1.5 N
D. 2.0 N


=======================================================


Answer was C. Here is explanation.

H3PO4 possesses three protons per molecule of acid, (which i know...)

so one and half molecules of CaCl2 is needed to react with each mole of

acid. (I can't understand this part 😕)

Anyone can explain this question for me?

 

[Danny289]

this following question from Kaplan GC workshop quiz.

What is the normality of a 1M solution of H3PO4 if titrated with CaCl2?

A. 0.5 N
B. 1.0 N
C. 1.5 N
D. 2.0 N


=======================================================


Answer was C. Here is explanation.

H3PO4 possesses three protons per molecule of acid, (which i know...)

so one and half molecules of CaCl2 is needed to react with each mole of

acid. (I can't understand this part 😕)

Anyone can explain this question for me?

2H3PO4 + 3CaCl2=====> 6HCL + Ca3(Po4)2
2/1=3/X ====> X=1.5

if you think a little deeper( it is better not to do that 🙂 ). you can argue the answer(1.5) is wrong , forget about my last quote !

 

[Cosmicnova]

oh, so I need to do "Stoichiometry" to find their numbers of mol?

Now, I think I understand it. Thank you, Danny!