The copper complex, Cu(NHs)SO, prepared earlier in the semester will be analyzed

Question

The copper complex, Cu(NHs)SO, prepared earlier in the semester will be analyzed for copper and ammonia independently. From this, the value of x, the coordination number, will be calculated. In part A, the copper content will be determined spectrophotometrically. The absorbances of five standard solutions prepared from 0.165 M Cu, as well as a solution of the prepared complex, will be determined at the analytical wavelength of 675nm. A Beer's Law Plot will be constructed (in Excel), from which the copper concentration in the prepared solution can be determined. In part B, the ammonia content will be determined by titration with a standardized hydrochloric acid solution. The mole ratio for this neutralization reaction is one mole NH, to one mole HCL MATERIALS lea Spec-20 spectrophotometer (allow to warm-up for 10-20 minutes) 5ea plastic cups lea 50mL Erlenmeyer flask 2es cuvettes Part A: lea 50mL burette and burette clamp 100 mL standardized HCl solution Part B: 2ea 250mL Erlenmeyer flasks Part A: Determination of Copper 1. Obtain approximately 20mL of the standard CuSO, solutions. 2. Select the proper filter! Using the top RIGHT dial, adjust the wavelength to 675nm. 3. Using the front LEFT dial, adjust the % Transmission to 0% Transmittance. 4. Add approximately 6mL of 1.0M HNO, (BE CAREFUL!) to a cuvette. Always use a Kimwipe Close to clean the outside of the cuvette. Put the cuvette into the sample holder - align properly. the cover and use the RIGHT dial to calibrate to 100% T Line a cuvette with Cuso, solution #1 . put it into the sample holder. Close the cover and read the Absorbance. Repeat step 5 for Cuso, solutions #2, 3, 4 & 5, Record these 5 absorbances on the data sheet. Tare a 50mL Erlenmeyer flask and add approximately 0.25g of the copper complex. Record the exact mass on the data sheet. Dissolve this in 10.0mL of 1.0M HNO, dispensed from a volumetric pinet Line a cuvette with this sample, add approximatelv 6ml., place in the samnle holder, close the cover, read and record the absorbance on the data sheet. 5. Add approximately 6mL of solution #1 to the cuvette and 6. 7. 8. Determine the standard solution concentrations using MIVI - M2V2. Prepare a Beer's Law plot and determine the molarity of copper in the sample. Part B: Determination of Ammonia Condition and fill a buret with the standardized hydrochloric acid and record its molarity Weigh approximately 0.8g of the copper complex into a tared 250ml Erlenmeyer flask. Record the mass of the copper complex. Dissolve the complex in 35-50mL distilled HO. Add 10-12 drops of methyl orange indicator to the flask and titrate with the standardized HCI until a salmon-pink endpoint is reached. Record the volume of the hydrochloric acid used. Perform a second determination by repeating steps 2 & 3. 1. 2. 3. 4.

Explanation / Answer

Step 1:formulas

M1V1 =M2V2

Beer's law =A =b. e. C

Step 2 :Molarity =mol /L

m=1 mol......... 63.54g Cu

Xmol........... 0.25g. Cu

Xmol = 1.31 mol Cu

6mL =0.006L

M=1.31mol Cu /0.006L =218

Note: we cant use Beer's law, because we dont have Absorbance's values.

Using Beer's law; the concentration is:

C=A/b. e

Related Questions

Navigate

• Browse (All)
• Browse T
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.