CHEM 208 Lecture Notes - Lecture 3: Sandpaper, Volumetric Flask, Graduated Cylinder

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21 Mar 2018

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25ml of about 0. 2m hcl will be made. Take 10 ml of hcl stock solution with a graduated cylinder and place in a 50 ml beaker and add 15ml of water using a graduated cylinder and mix well. Measure 5. 07 grams of kno3 and place it in a 150 ml beaker and add 125 ml of water. Do the same for nacl but use 0. 73 g of nacl. Prepare 0. 2 m of ki solution by measuring 4. 2 g of ki and placing it in a 150 ml beaker and adding 130ml. Prepare 0. 05m na2s2o3 by weighing 0. 3 grams on an analytical balance, be very accurate. Place it in a beaker and dissolve with a little bit of water. Wash the beaker few times with distilled water and add it into the 25ml volumetric flask and make up to the mark with distilled water.

Related Questions

Please help me calculate the theoretical pH of a buffer solution containing 0.012mol NaC2H3O2 + 0.012mol of HC2H3O2 in 25mL of solution with an added 6M HCl.

5 mL of standard aspirin solution (200ppm) is pipetted into a beaker and 1.5 mL of 0.5 M NaOH is added. The aspirin solution is then transfered into a 25-mL volumetric flask where 4 mL of 0.1 M Fe3+ solution is added to the flask. It is then diluted to the mark (25ml) with distilled water. What is the new concentration of the Asprin in mg/mL?

Help Please!

A) preparation of buffer solution:

6.606g of sodium acecate trihydrate was weighed out (MM=136 g/mole) in a small beaker. 25 ml of water was added to 100 ml volumetric flask. 8.00 ml of a 6 M acetic solution was added.

B) pH of water with added NaOH and HCl

Prepare two beakers (Beaker 1 and Beaker 2) and pipet 25 mL of deionized water into each beaker. Measure the pH of the water in the beaker. In Beaker 1, add 1 drop of 1 M NaOH into the beaker. Stir and read the pH of the resulting mixture. Add an additional drop of the 1 M NaOH solution to the beaker, stir and measure the pH. Add an addition 4 drops for a total of 6 mL and then 4 more drops for a total of 10 drops, add 10 more drops and finally using a volumetric or graduated pipet, add 1 mL of 1M NaOH and read the pH after each addition. To Beaker 2, add 1 drop of 1 M HCl into the beaker. Stir and read the pH of the resulting mixture. Add an addition 1 drop of the 1 M HCl solution to the beaker, stir and measure the pH. Add an addition 4 drops for a total of 6 drops and then an additional 4 drops for a total of 10 drops, add 10 more drops and finally add 1 mL of 1 M HCl, read the pH after each addition.

C) pH of buffer solution with added NaOH and HCl

Prepare two additional beakers (Beaker 3 and Beaker 4). Pipet 25 mL of the prepared buffer solution from part A into each beaker. Measure the pH of the buffer solution. To Beaker 3, using a graduated pipet, add 1 mL of 1 M NaOH. Stir and read the pH of the resulting mixture. Add an addition 1 mL of the 1 M NaOH solution to the beaker, stir and measure the pH. Add 4 mL more for a total of 6 mL and then an additional 4 mL for a total of 10 mL, finally add two 10 mL additions, read the pH after each addition. To Beaker 4 containing 25 mL of buffer, repeat the steps of beaker 3 with the addition of 1 M HCl into the beaker. Stir and read the pH after each addition.

Questions: only need 4-6

4)Calculate the pH of the buffer solution after 2 mL of NaOH was added to Beaker 3 and after 2 mL of HCl was added to Beaker 4. Compare this to your measured pH

5)Compare the measured pH for the addition of 1M NaOH and 1 M HCl to beaker 3 and 4 with the buffer solutions to the measured pH in Beaker 1 and 2 with the water.

6)From the measured pH of the acetic acid buffer solution above before the addition of any NaOH or HCl solution, calculate the K?a for acetic acid. Compare to CH3COOH Ka value which is 9.1x10^-6?

Water				Buffer solution
Beaker 1		Beaker 2		Beaker 3		Beaker 4
Total Volume of 1 M NaOH added	pH	Total Volume of 1 M HCl added	pH	Total Volume of 1 M NaOH added	pH	Total Volume of 1 M HCl added	pH
0 mL	7.08	0 mL	7.01	0 mL	6.02	0 mL	6.05
1 drop	9.86	1 drop	3.13	1 mL	11.87	1 mL	5.52
2 drops	10.38	2 drops	2.69	2 mL	12.38	2 mL	5.22
6 drops	10.86	6 drops	2.25	6 mL	12.74	6 mL	4.46
10 drops	11.08	10 drops	2.02	10 mL	12.87	10 mL	3.53
20 drops	11.35	20 drops	1.76	20 mL	12.99	20 mL	1.04
2 mL = (40 drops)	11.68	2 mL	1.47	30 mL	13.06	30 mL	0.89

CHEM 208 Lecture Notes - Lecture 3: Sandpaper, Volumetric Flask, Graduated Cylinder

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