Saturday 20 October 2012

Glassware used in stock solution?

Provide the calculations and experimental procedure necessary to make the following solution: 10.00 mL of a 0.0300 M solution of CH3COOH from a stock solution with a concentration of 0.0780 M.

Use the equation: M1V1 = M2V2.
V1 = (10.00 mL)(0.0300 mol/L) = 0.300 mol
V1 = (0.300 mol/0.0780 mol/L) = 3.85 mL

--Explain to a person new to lab how to make this solution. Specifically state "which glassware" you would use and include the appropriate precision of said glassware in your calculations.

Here is the list of available glassware that can be used:
-Beakers, mL:
600
400
250
150
100
50
30
20
-Burets, mL:
50
25
-Graduated Cylinders, mL:
100
50
10
-Volumetric Flasks, mL:
100
50
25
10
-Volumetric Pipets, mL:
25
20
10
8
7
5
3
2
1

Obtain a 10.00 mL volumetric flask and rinse with distilled water. Add about 5.00-7.00 mL of distilled water to the volumetric flask. Obtain the stock solution from the carboy with the appropriate marking for CH3COOH. Add more than the desired amount of stock solution to a 10.00 mL graduated cylinder, in this case, 5.00 mL more, to prevent loss of substance due to mishandling. Use a 10.00 mL graduated cylinder to dole out the 3.85 mL of CH3COOH to the 10.00 mL volumetric flask. Stopper the flask and invert several times to mix the contents well. Add more distilled water, until the meniscus is level with the calibration mark. Stopper the flask and invert 20 times.

Given my list of available glassware above, is there a more precise way of transferring the needed 3.85 mL of CH3COOH to the 10.00 volumetric flask?

I have heard of the Class A, 5 ml volumetric serological pipe and Class A adjustable pipettor (1000 - 5000 ul), which is adjustable to 10ul, but it can't be included, since it's not on the list.

No comments:

Post a Comment