TBR neturalization question

[californiamed]

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Which of the following is required to neutralize 5mL of 0.20M CaCO3?

A)10mL 0.10 N NaOH
B) 10mL 0.10 N HNO3
C) 10mL 0.30 N H3PO4
D) 10mL 0.20 N NaOH

Answer: D.

I get why A i eliminated, because it's a base and you need an acid. I used MV = MV and got B as the answer. The explanation wrote out a reaction that said something about 2H+. Are we suppose to know how to write the reaction too?? So confused by this problem.

 

[l0x]

Which of the following is required to neutralize 5mL of 0.20M CaCO3?

A)10mL 0.10 N NaOH
B) 10mL 0.10 N HNO3
C) 10mL 0.30 N H3PO4
D) 10mL 0.20 N NaOH

Answer: D.

I get why A i eliminated, because it's a base and you need an acid. I used MV = MV and got B as the answer. The explanation wrote out a reaction that said something about 2H+. Are we suppose to know how to write the reaction too?? So confused by this problem.

CaCO3 is a dibasic species that accepts 2 protons per parent molecule. Thus it requires twice as much acid to neutralize it than a monobasic species.

The reaction isn't anything more complicated than a simple acid base reaction which you should be very familiar with.

 

[californiamed]

CaCO3 is a dibasic species that accepts 2 protons per parent molecule. Thus it requires twice as much acid to neutralize it than a monobasic species.

The reaction isn't anything more complicated than a simple acid base reaction which you should be very familiar with.

How are we suppose to know that? So we need to know that CaCO3 has a -2 charge for the MCAT? Thus it needs 2 H's to neutralize?

Urgh! 😡

 

[milski]

CaCO₃ has a charge of 0, CO₃^2- has a charge of -2. That should be fairly obvious from knowing that Ca's ions are Ca²⁺. The later is used in so many context that getting by without knowing it seems virtually impossible.

 

[MTHFR]

OP wrote the answer choices incorrectly. (D) should have read 0.2 N HCl, not 0.2 N NaOH.