Calculate the concentrations of potassium nitrate used in the laboratory exercis

ID: 1024548 • Letter: C

Question

Calculate the concentrations of potassium nitrate used in the laboratory exercise in units of g KNO_3/100 g H_2O. In each case the mass of potassium nitrate used is 10.0 g. Assume the density of room temperature water (the water measured with the pipette) is 1.00 g/mL. Complete the following table. Save a copy of your calculations to use when preparing a graph of your results from this experiment. Plot the solubility data (Y-axis) from the following table as a function of temperature (X-axis). A different symbol for each set of data points should be used in order to make it possible to distinguish between the four plots on the graph. As an example, the NaCl data could be done with circles encompassing each data point, while the KC1 data is done by using squares to encompass the points, etc. You also might want to use color coding for each of the lines. The remainder of the data (at different temperatures from those temperatures in the data table below) for potassium nitrate will be obtained during your experiment. Place a caption and legend on the set of plots describing the contents of the graph.

Explanation / Answer

1. Mass of KNO3 added in each case is 10.0 gm; the density of water at room temperature is 1 gm/mL. Therefore, the mass of 1 mL of water at room temperature is (1 mL)*(1 gm/1 mL) = 1 gm……(1).

Again, we have dissolved 10.0 g potassium nitrate in the given volumes of water; therefore, the mass of KNO3 dissolved in 100 g water is given as [(10.0 g KNO3)/(mass water, g)]*(100 g water) …..(2)

Now, let us fill in the table given below:

Solution no.

Vol. water, mL

Mass water, g

[employ (1) from above]

Mass KNO3, g KNO3 in 100 g water [employ (2) from above]

Conc’n, g KNO3/100 g H2O (we round off to two significant figures)

8.00

(10.0/8.00)*100 = 125

1.25

11.00

90.91

0.91

14.00

71.43

0.71

19.00

52.63

0.53

27.00

37.03

0.37

39.00

25.64

0.26