midterm q3c

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midterm q3c

Postby WGaines_2E » Mon Mar 09, 2020 9:33 pm

A buffer solution made with NH3 and NH4Cl has a pH of 10.1. Which procedure(s) could be used to lower the pH?

1) adding HCl
2)Adding NH3
3) adding NH4Cl

A) 1 only
B) 2 only
C) 1 and 3
D) 2 and 3

To solve this did you need to write out the balanced equation? I put a originally but now I'm thinking its b?

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Joined: Sat Jul 20, 2019 12:16 am

Re: midterm q3c

Postby chemboi » Mon Mar 09, 2020 9:37 pm

if what you're adding will dissociate into a proton, it will make the solution more acidic. HCl is an immediate candidate. I believe NH4+ is considered a weak acid, so C seems like a good answer.

Deena Doan 2F
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Re: midterm q3c

Postby Deena Doan 2F » Thu Mar 12, 2020 9:58 am

For this one, I had to think about it logically like the person above said. If you want to lower the pH, you have to add an acid. That's why A and C were the answers since they were both acidic.

Manav Govil 1B
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Re: midterm q3c

Postby Manav Govil 1B » Thu Mar 12, 2020 10:05 am

This was a bit of a tricky question - much due to the fact that we did not know what buffers were!

Buffers have a region where the pH does not change as much despite adding acids or bases. The way to make a solution decrease in pH is by adding more acidic compounds, so one would need to identify the acidic compounds and add them to the buffer. That's why the answer is C.

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