Question

Laboratory goggles must be worn! A) Preparation of Solutions from Concentrated Solution In this part the experiment you will prepare several dilute solutions from the more concentrated cobalt nitrate solution 1. Read the label on the provided cobalt nitrate solution and record the molarity accurately. su-olu 563/ 316.603:48 صلاح 2. 3. 4. Molarity of Ca(NO3)2 solution 182.95 g/mol Obtain a 25-ml buret. Examine its markings, the line that spans the entire circumference occur for each milliliter. The smaller lines indicate each tenth of a milliliter. The spacing between these lines will allow you to estimate the volume to the nearest 0.01 mL. Mount the buret on a ring stand using a buret clamp. Close the stopcock. Using a funnel, fill the buret with your cobalt solution to the 12-mL mark (any reading between 11 and 13-mL is OK). Using a 50-ml. beaker as a receiver, open and close the stopcock so the liquid drains rapidly to flush out air bubbles in the tip of the buret. Inspect and make sure that the tip of the buret is completely filled and contains no air bubbles. Remove the funnel and adjust the meniscuses at exactly 15.00 mL mark (again, use the 50-ml beaker as a receiver). Obtain four test tubes, numbered 1 to 4. You will dispense the cobalt solution from the buret into each of these four test tubes. Carefully: Drain 1.00 mL of the solution to test tube #1 (initial buret 15.00 ml; final reading 16.00 mL.) Drain 2.00 mL of the solution to test tube #2 (initial buret 16.00 ml.; final reading 18.00 ml.) Drain 3.00 mL of the solution to test tube #3 (initial buret 18.00 ml; final reading 21.00 ml.) Drain 4.00 mL of the solution to test tube #4 (initial buret 21.00 mL ; final reading 25.00 mL.) You will use the same buret to measure the volume of the required DI water. Drain the rest of the cobalt solution into the 50-ml. beaker you used before. Remove the buret from the ring stand and rinse the buret with several portions of DI water as demonstrated by your instructor Making sure that the tip of the buret is completely filled with the DL water, mount the buret on the ring stand. Now, fill the buret, using your plastic wash bottle, with the DI water to exactly 15.00 mL mark. No funnel needed. Lab 5-1

Answer 1

Question: To calculate the amount of Co(NO3)2 in each test tube.

Answer:

Given, the volume of cobalt solution and its molarity as follows

Volume of Co(NO3)2 solution	Molartiy of the solution
1 mL	3 M
2 mL	7.6 M
3mL	13.2 M
4mL	19.2 M

Molarity M = mol of solute / L of the solution

Rewriting the equatio we have, Moles of solute = Molarity M x L of the solution

moles of Co(NO3)2 in Test tube 1 = 3 M x 1 x 10-3 L

moles of Co(NO3)2 in Test tube 1 = 3 x 10-3 ML

moles of Co(NO3)2 in Test tube 2 = 7.6 M x 2 x 10-3 L

moles of Co(NO3)2 in Test tube 2 = 15.2 x 10-3 ML

moles of Co(NO3)2 in Test tube 3 = 13.2 M x 3 x 10-3 L

moles of Co(NO3)2 in Test tube 3 = 39.6 x 10-3 ML

moles of Co(NO3)2 in Test tube 4 =  19.2 M x 4 x 10-3 L

moles of Co(NO3)2 in Test tube 4 = 76.8 x 10-3 ML