Cu+ reacts with neocuproine to form the colored complex (neocuproine)2Cu+,

Cu+ reacts with neocuproine to form the colored complex (neocuproine)2Cu+, with an absorption maximum at 454 nm. Neocuproine is particularly useful because it reacts with few other metals. The copper complex is soluble in 3-methyl-1-butanol (isoamyl alcohol), an organic solvent that does not dissolve appreciably in water. In other words, when isoamyl alcohol is added to water, a two-layered mixture results, with the denser water layer at the bottom. If (neocuproine) 2Cu+ is present, virtually all of it goes into the organic phase. For the purpose of this problem, assume that the isoamyl alcohol does not dissolve in the water at all and that all of the colored complex will be in the organic phase. Suppose that the following procedure is carried out:

1. A rock containing copper is pulverized, and all metals are extracted from it with strong acid. The acidic solution is neutralized with base and made up to 250.0 mL in flask A.

2. Next, 10.00 mL of the solution are transferred to flask B and treated with 10.00 mL of reducing agent to convert Cu2+ to Cu+. Then 10.00 mL of buffer are added so that the pH is suitable for complex formation with neocuproine.

3. 15.00 mL of this solution are withdrawn and placed in flask C. To the flask are added 10.00 mL of an aqueous solution containing neocuproine and 20.00 mL of isoamyl alcohol. After the mixture has been shaken well and the phases allowed to separate, all (neocuproine)2Cu+ is in the organic phase.

4. A few milliliters of the upper layer are withdrawn, and the absorbance at 454 nm is measured in a 1.00-cm cell. A blank carried through the same procedure gives an absorbance of 0.056.

(a) Suppose that the rock contained 1.00 mg of Cu. What will be the concentration of Cu (mol/L) in the isoamyl alcohol phase?

(b) If the molar absorptivity of (neocuproine)2Cu+ is 7.90 × 103 M-1 cm-1, what will be the observed absorbance? Remember that a blank carried through the same procedure gave an absorbance of 0.056.

(c) A rock is analyzed and found to give a final absorbance of 0.874 (uncorrected for the blank). How many milligrams of Cu are in the rock?

How Our Website Works


It has never been easier to place your order. Fill in the initial requirements in the small order form located on the home page and press “continue” button to proceed to the main order form or press “order” button in the header menu. Starting from there let our system intuitively guide you through all steps of ordering process.


All your payments are processed securely through PayPal. This enables us to guarantee a 100% security of your funds and process payments swiftly.


Next, we match up your order details with the most qualified freelance writer in your field.


Once we have found the most suitable writer for your assignment, they start working on a masterpiece just for you!


Once finished, your final paper will be available for download through your personal dashboard. You will also receive an email notification with a copy of your paper attached to it. Sometimes, the writer may leave a note for you about the order in case there is any additional information that they need to give you.

Leave a Reply

Your email address will not be published.