Welcome Guest Search | Active Topics |

Tag as favorite
AAMC Question Pack
Options
Previous Topic Next Topic
Daniela_5535
#1 Posted : Monday, June 08, 2020 2:34:04 PM
Rank: Member

Groups: Registered
Joined: 5/3/2020
Posts: 18

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hello,

I’m confused on an AAMC question (Chemical and Physical Foundations of Biological Systems - Passage 3), it states that in a solution of NiSo4 is dissolved in enough water to make 50 ml of a green solution and 7 g of Na2CO3 is dissolved in enough water to make 50 ml of a colourless solution. The two solutions are mixed and a green precipitate forms. The resulting slurry is divided into two portions and one portion is added an excess of 6 M HCL, which results in the disappearance of the precipitate and a rapid evolution of a gas. To the second portion is added a few mm of 6 M NH3. The precipitate dissolves and a blue solution forms.

If red litmus paper is dipped into NA2 CO3 solution it will :

- turn blue because carbonate reacts with water to produce OH- .

However, I chose “turn blue, because sodium ions form sodium hydroxide in water” and was wondering why it was incorrect?

Thank you.
Back to top
Report?
INSTR_Molly_59
#2 Posted : Monday, June 08, 2020 5:34:58 PM
Rank: Member

Groups:
Joined: 7/12/2019
Posts: 28

Thanks: 0 times
Was thanked: 0 time(s) in 0 post(s)
Hi Daniela, its because in water, strong acids/bases such as NaOH would ionize to form Na+ and OH- ions, and would not form the compound NaOH. Weak bases will indeed protonate in presence of water, which generates OH- ions that contributes to the basicity of the solution.

Hope this helps! :)
Back to top
Report?
Users browsing this topic
Guest (2)
Tag as favorite
You cannot post new topics in this forum.
You cannot reply to topics in this forum.
You cannot delete your posts in this forum.
You cannot edit your posts in this forum.
You cannot create polls in this forum.
You cannot vote in polls in this forum.

Clean Slate theme by Jaben Cargman (Tiny Gecko)
Powered by YAF | YAF © 2003-2009, Yet Another Forum.NET
This page was generated in 0.077 seconds.