ANALYTICAL CHEMISTRY PLEASE PLEASE PLEASE SHOW WORK THAT I CAN READ!! THANK YOU!
ID: 480042 • Letter: A
Question
ANALYTICAL CHEMISTRY
PLEASE PLEASE PLEASE SHOW WORK THAT I CAN READ!! THANK YOU!!!!
2. (10 pts) 12.104g of KCl is weighed out using an analytical balance, placed in a 100 mL volumetric flask, and DI water added to bring the solution volume to 100mL. This solution is labeled Solution 1. In a second experiment, 6.054g of KCl is weighed out using the same analytical balance, placed into a graduated cylinder, and DI water added until the meniscus has reached the 50 mL mark. This solution is labeled Solution 2. The measurement uncertainty (standard deviation of the measured value) of the analytical balance used is +/- 0.001 g. The measurement uncertainty of the volumetric flask is +/- 0.06mL. The measurement uncertainty of the graduated cylinder is +/- 0.5 mL. Calculate the Molarity of Solution 1 and the uncertainty in the Molarity. Calculate the Molarity of Solution 2 and the uncertainty in the Molarity. Which is the better choice of glassware to use to in making calibration standards? [SHOW YOUR WORK].
2. (10 pts) 12.104g of KCl is weighed out using an analytical balance, placed in a 100 mL volumetric flask, and Dl water added to bring the solution volume to 100mL. This solution is labeled Solution 1. In a second experiment, 6.054g of KCl is weighed out using the same analytical balance, placed into a graduated cylinder, and DI water added until the meniscus has reached the 50 mL mark. This solution is labeled Solution 2. The measurement uncertainty (standard deviation of the measured value) of the analytical balance used is 0.001 g. The measurement uncertainty of the volumetric flask is 0.06m L. The measurement uncertainty of the graduated cylinder is 0.5 mL Calculate the Molarity of Solution 1 and the uncertainty in the Molarity. Calculate the Molarity of Solution 2 and the uncertainty in the Molarity. Which is the better choice of glassware to use to in making calibration standards? [SHow YOUR WORK]Explanation / Answer
ANSWER
Molarity in case first = (mass of KCl / molar mass of KCl X volume) X 1000
Let us represent the uncetainty in mass by M and uncertainty in volume by V
While taking the uncertainty into acount the molarity is given as
M1 = (12.104/ 74.5 X100) X 1000 [1 +- (M/M + V/V)] X100
(IN DIVISION SUM OF % UNCERTAINTY IS ADDED THE MEASUREMENT)
M1 = 1.6246[1+ - (0.001/12.104) + (0.06/100)] X 100
M1 = 1.6246[1+- (0.00008+ (0.0006)] X 100
M1 = 1.6246(1+- 0.068)
M1 = 1.623 +- 0.068
Similarly
M2 = (6.054 / 74.5 X50) X 1000 [1 +- (0.001/6.054 + 0.5/50)] X100
M2 = 1.625 [1 +- 1.02]
M2 = 1.625 +- 1.02
Volumetric flask is the better choice as the uncertainty is less.
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