Thread: Solution determination lab

I've got a lab coming up in my AP chemistry class, and I wanted to get a bit of help from here (I hope this is the right section for this, I couldn't find the Homework Help section after the site renovation). In this lab, we get 12 chemicals in numbered containers (1-12). We know what the 12 possible chemicals are, but we don't know which is in which container. The 12 chemicals are the following:

.2M Potassium Chromate
1.0M Aluminum Chloride
1.0M Sodium Carbonate
6.0M Hydrochloric Acid
6.0M Sodium Hydroxide
0.1M Silver Nitrate
6.0M Ammonia
0.1M Lead (II) Nitrate
0.1M Ferric Nitrate
1.0M Sodium Acetate
0.1M Copper (II) Sulfate
0.1M Nickel Chloride

I determined the following process using properties of the solutions and combinations of them. This is what I figured out:

1) The following solutions can be determined by observable factors:
Potassium Chromate - Yellow Solution
Aluminum Chloride - White/Pale Yellow solution
Copper (II) Sulfate - Blue solution
Nickel Chloride - Green solution
Ammonia - The ass-smelling solution
Sodium Hydroxide - The extremely basic solution (Use of litmus paper)

2) React the Potassium Chromate solution with the non-determined solutions:
Silver Nitrate - Red solution with maroon precipitate
Lead (II) Nitrate - Yellow-Orange precipitate

3) React the Silver Nitrate solution with the remaining non-determined solutions:
Sodium Carbonate - Yellow Precipitate
Hydrochloric Acid - White Precipitate
Sodium Acetate - Grayish Precipitate

4) Only remaining solution is Ferric Nitrate


Would the steps I provided allow me to determine all the solutions with precision? There are a couple steps which I am unsure about (Would NaOH be significantly more basic on litmus paper than the other basic solutions? Is Silver Acetate noticeably gray?). If anybody could verify that I am using decently planned steps, or if I haven't, provide some input on how I could fix my process, I would really appreciate it!

Originally Posted by starfire09

I've got a lab coming up in my AP chemistry class, and I wanted to get a bit of help from here (I hope this is the right section for this, I couldn't find the Homework Help section after the site renovation). In this lab, we get 12 chemicals in numbered containers (1-12). We know what the 12 possible chemicals are, but we don't know which is in which container. The 12 chemicals are the following:

.2M Potassium Chromate
1.0M Aluminum Chloride
1.0M Sodium Carbonate
6.0M Hydrochloric Acid
6.0M Sodium Hydroxide
0.1M Silver Nitrate
6.0M Ammonia
0.1M Lead (II) Nitrate
0.1M Ferric Nitrate
1.0M Sodium Acetate
0.1M Copper (II) Sulfate
0.1M Nickel Chloride

I determined the following process using properties of the solutions and combinations of them. This is what I figured out:

1) The following solutions can be determined by observable factors:
Potassium Chromate - Yellow Solution
Aluminum Chloride - White/Pale Yellow solution
Copper (II) Sulfate - Blue solution
Nickel Chloride - Green solution
Ammonia - The ass-smelling solution
Sodium Hydroxide - The extremely basic solution (Use of litmus paper)

2) React the Potassium Chromate solution with the non-determined solutions:
Silver Nitrate - Red solution with maroon precipitate
Lead (II) Nitrate - Yellow-Orange precipitate

3) React the Silver Nitrate solution with the remaining non-determined solutions:
Sodium Carbonate - Yellow Precipitate
Hydrochloric Acid - White Precipitate
Sodium Acetate - Grayish Precipitate

4) Only remaining solution is Ferric Nitrate


Would the steps I provided allow me to determine all the solutions with precision? There are a couple steps which I am unsure about (Would NaOH be significantly more basic on litmus paper than the other basic solutions? Is Silver Acetate noticeably gray?). If anybody could verify that I am using decently planned steps, or if I haven't, provide some input on how I could fix my process, I would really appreciate it!

Hello,

you are on the right track... If you need specific procedures consult an undergraduate organic lab text book. One I recommend to the undergraduates that I've TAed is: Experimental Organic Chemistry - Standard and Microscale by L.M. Harwood, C.J. Moody and J.M. Percy....

* For safety reasons you should verify with your instructor prior to beginning your lab any procedures that you wish to utilize that are not outlined in the lab manual provided to you by your instructor for the class.

To find out more specifics about each reagent you should look them up in the above mentioned or a similar text to find a procedure and pertinent information in more detail.

You can find the information you seek regarding the bases by using Evans pka table - if you're unsure how to utilize the pka table let me know....
you'll want to note the strength of the conjugate acid shown... remember that stronger acids have weaker conjugate bases... and the pka of an alcohol is approximately 16...

Silver acetate is noticeably white/gray see - http://en.wikipedia.org/wiki/Silver_acetate - this will depend on quantities used and the quality of the reagent but there WILL be a noticeable color change...

hope this helps. : )

Good luck