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April 22, 2021, 10:18:47 am

Author Topic: HSC Chemistry Sample examination mod6 q6  (Read 584 times)  Share 

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tienn_le

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HSC Chemistry Sample examination mod6 q6
« on: November 06, 2019, 12:56:07 pm »
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Hi
Could someone explain for me module 6 question 6 in the HSC Chemistry sample examination?

InnererSchweinehund

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Re: HSC Chemistry Sample examination mod6 q6
« Reply #1 on: November 06, 2019, 05:57:51 pm »
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Hi
Could someone explain for me module 6 question 6 in the HSC Chemistry sample examination?

Hi there!

For this question I chose one common base (NaOH) and used it to 'titrate' the rest of the acids.

As the question states, they want to know which acid would require the most base to neutralise it.
From here, I wrote out each of the complete molecular equations, to determine the number of moles required to neutralise each acid.
By doing this, it is clear that in order to have a balanced equation, the phosphoric acid (H3PO4) required more moles of NaOH (base) to neutralise it, than the other bases. The higher number of moles of base required, the higher volume of base needed (as the base is constant).
As this is a multiple choice question, and you don't need to prove the difference in volumes, and can therefore use this information to determine that the answer is B.

Hope this is helpful and good luck tomorrow!
 :D