Homework Help 12.65

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Andrew Uesugi 3I
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Joined: Wed Sep 21, 2016 2:56 pm

Homework Help 12.65

Postby Andrew Uesugi 3I » Mon Nov 28, 2016 8:36 pm

So I need help on this question.

Determine whether an aqueous soluiton of each of the following salts has a pH equal to, greater than, or less than 7. If pH > 7 or pH < 7, wrtie a chemical euqation to justfy your answer.

a) Nh4Br
etc.

I'm confused. All I'm seeing are given formulas. What are you supposed to see from the solution? Can anybody explain?

Thanks

Brian Huynh 3D
Posts: 20
Joined: Wed Sep 21, 2016 2:58 pm

Re: Homework Help 12.65

Postby Brian Huynh 3D » Mon Nov 28, 2016 9:51 pm

Typically, when doing these problems, you want to look at the molecular formula and see if it is a base or an acid when in water. NH4Br will dissociate into NH3 and H+ ion(or hydronium), thus NH4 is an acid because it donated an electron and the solution is acidic due to the increase of H+ ion.

Lauren Trent 2A
Posts: 21
Joined: Wed Sep 21, 2016 2:56 pm

Re: Homework Help 12.65

Postby Lauren Trent 2A » Mon Nov 28, 2016 10:00 pm

In order to determine if an aqueous solution of these compounds will have a pH greater, equal to, or less than 7, you must write out the chemical equation that would result by reacting these compounds with water. The salts you are given will ionize and the ions will react with the water to form acids/bases. For example, in part a, reacting NH4Br with water would result in the NH4+ ion donating a hydrogen ion to the water molecule, so the resulting solution will be acidic and have a pH greater than 7. In part b, the CO3^2- ion will accept a hydrogen ion from the water molecule, resulting in a basic solution with a pH less than 7. In part d, the double replacement reaction would produce HBr + KCl, a strong acid and a strong base, so the resulting solution would neutralize and have a pH equal to 7.

Navarro_Bree_1D
Posts: 24
Joined: Wed Sep 21, 2016 3:00 pm

Re: Homework Help 12.65

Postby Navarro_Bree_1D » Tue Nov 29, 2016 7:40 pm

I also had a question about this too. For part e and part f, why do you attach 6 molecules of water to the transition metal?

Julie Barreto 3A
Posts: 21
Joined: Wed Sep 21, 2016 2:56 pm

Re: Homework Help 12.65

Postby Julie Barreto 3A » Tue Nov 29, 2016 8:55 pm

How can a pH be less than 7 but be basic??and vice versa ...doesn't make sense??


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