A sample of a CaCl_2-2H_2O/K_2C_2O_2+H_2O solid salt mixture is dissolve in -150

Question

A sample of a CaCl_2-2H_2O/K_2C_2O_2+H_2O solid salt mixture is dissolve in -150 mL of deionized water previously adjusted to a PH that is basic. The precipitate, after having been filtered, was air-dried and weight. Data for Trial were obtained as shown. Complete the following table. Record calculated values with the reet number of significant figures. 4. b. For Trials 2 and 3, the percent CaCl_2H_2O in the mixture was 39.7% and 28.4% respectively a. What is the average percent of CaCl_2.2H_2O in the sample' Data Analysis. B b. What are the standard deviation and the relative standard deviation (%RSD) for the percent of CaCl_2.2H_2O in the sample? Data Analysis, C and D.

Explanation / Answer

4)

a) let there be 100 g of each of the samples

Thus, mass of CaCl2.2H2O in the 2 samples = 39.7 g & 28.4 g

Thus, total mass of the 2 samples = 200 g

total mass of CaCl2.2H2O in the 2 samples = 68.1 g

Thus, average % of CaCl2.2H2O = (68.1/200)*100 = 34.05%

Now, deviation of the 2 samples = (34.05 - 39.7) = -5.65 & (34.05 - 28.4) = 5.65

Now, variance = 2*(5.65)2 = 63.845

Thus, standard deviation = sqrt(variance) = 7.99

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