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UnsafeAtAnySpeed - 26-6-2016 at 11:27

I am new to this website, glad to be here.

I want to:
#1. I know some chemistry but I want to learn more.
#2. Work with methods of making hard to get chemicals like iodine.
#3. Work with electro-chemistry..
#4 Just about any DIY technology.

No illegal intent here, I am just interested in chemistry.

Question for forum:
I mixed 50 mL of Zinc Sulfate and 50 mL of Potassium Chromate Solution together and heated them to boiling and no reaction.
I expected a double replacement reaction where I would have a Zinc Chromate precipitation and Potassium Sulfate, but got nothing.
What am I doing wrong?


[Edited on 26-6-2016 by UnsafeAtAnySpeed]

[Edited on 26-6-2016 by UnsafeAtAnySpeed]

PHILOU Zrealone - 26-6-2016 at 11:47

Quote: Originally posted by UnsafeAtAnySpeed  
I am new to this website, glad to be here.

I want to:
#1. I know some chemistry but I want to learn more.
#2. Work with methods of making hard to get chemicals like iodine.
#3. Work with electro-chemistry..
#4 Just about any DIY technology.

No illegal intent here, I am just interested in chemistry.

Question for forum:
I mixed 50 mL of Zinc Sulfate and 50 mL of Potassium Chromate Solution together and heated them to boiling and no reaction.
I expected a double replacement reaction where I would have a Zinc Chromate precipitation and Potassium Sulfate, but got nothing.
What am I doing wrong?

Welcome.
This forum is the good place to learn, but:
-read a lot before posting
-for simple question go to beginning section
-and search with the forum search tool with keywords to get almost more than what you can dream of

About your practical problem:
-maybe both your solution were too diluted and the resulting mix below the solubility product --> in solution.
-maybe your solution is supersaturated because of the heating and it just needs a nucleation site to start precipitate in the cold
-maybe your product are not what they are...not ZnSO4 of not K2CrO4...

hissingnoise - 26-6-2016 at 11:58

Being insoluble, zinc chromate should precipitate, and without heating.

If you try again, with the correct stoichiometry this time, and it fails, then your reagents are likely questionable!

morsagh - 26-6-2016 at 12:32

Use higher concentrations of solutions to get better yeld

aga - 26-6-2016 at 12:43

Welcome to Science Madness !

First, it's best to find an existing procedure, then try to follow/replicate it.

There are a great many things already known/done/worked out, so re-inventing the wheel is just a waste of time (although fun at the time).

Second, post a write-up and Photos of your chemistry exploits, as a picture says so much more than mere words.

Beginnings is the area for unreferenced questions, unless it's Wild speculation, in which case you'll need Whimsy.

Photos of what you've already tried also show beyond doubt that you're Actually interested and active in chemistry.

The reason i said that last bit :

Over the past few months we've been plagued by someone (or someones) who know(s) a teensy weensy little bit about chemistry, yet never actually Does any.

They seem to sign up several new user accounts every day, just so that they can post crap on this board.

Browse, find the Good stuff, experiment and enjoy !

UnsafeAtAnySpeed - 26-6-2016 at 15:55

Thanks for all of your reply's!
It still did not work.
I will order good quality chemicals and use stoichiometric proportions next time. The chemicals I used were not the best. Potassium Chromate: fish tank accessories supply store, Zinc Sulfate: homemade.
And I will read this website more before posting.

Boffis - 29-6-2016 at 03:26

Also check the pH, if it is too acid the dichromate ion will predominate and this will prevent precipitation because as zinc chromate forms the H+ ion concentration will increase until equilibrium is reached. Zinc chromate is easily soluble in acids and dichromate ions do not precipitate zinc.

The Volatile Chemist - 29-6-2016 at 10:38

Also try chilling, or using a slight excess of chromate. And pH is a good point. Wikipedia gives the unhelpful 'Insoluble' without a Ksp.

Welcome to the forum. For future small questions, try asking them in the short questions thread:
https://www.sciencemadness.org/whisper/viewthread.php?tid=25...
They'll get answered faster there, instead of ignored.