Santa Monica College Chemistry 11 Name: Date: Lab Section Prelab Assignment: The

Question

Santa Monica College Chemistry 11 Name: Date: Lab Section Prelab Assignment: The Densities of Solutions and Solids Each Five students decide to determine the density of a sample of liquid chioroform. student uses a graduated cylinder to obtain the chloroform volume and a balance to obtain the chloroform mass. Their density values are shown in the table below. 1. Density (g/mL) 1.45 1.55 1.60 1.38 1.44 Student cylinder beaker a) Determine the average density and the standard deviation in this density dataset Avg: Std Dev The students then decide to determine the chloroform density using a beaker to measure volume. Their density results are displayed in the graph above, along with those obtained using the cylinder. Which glassware yielded the more precise measurements? Explain. b) c) In Part A of this lab, you will perform a similar analysis of density data obtained for distilled 2. A student decides to use the technique employed in Part B of this lab to determine the density of vodka. He first fills a buret with vodka to an initial volume of 1.52 mL. He ther drains out some of the vodka into an empty beaker with a mass of 13.687 g. The final buret volume is 9.62 mL. If the combined mass of the beaker and vodka is 21.123 g. what is the the density of the vodka? Give your answer to the correct number of significant figures The Densities of Solutions and Solids Page 1 of 2 F7 F8 F10 F12 Del

Explanation / Answer

1. a) Average Density = (1.45+1.55+1.60+1.38+1.44) / 5

Average Density = 1.484 g/mL

b) More precision is obtained with glass cylinder since all the experimental results lie close to a single point density as compared to the scattered values in glass beaker.

3. a) Mass of Gold Sample = 70.773 - 10.495

Mass of Gold Sample = 60.278 g

b) Mass of water in vial with gold = 76.286 - 70.773

Mass of water in vial with gold = 5.513 g

Density of water = 0.997 g/mL

Volume of water = 5.513 / 0.997 = 5.3 mL

c) Mass of water filled with water only in vial = 19.119 - 10.495

Mass of water filled with water only in vial = 8.624 g

Density of water = 0.997 g/mL

Volume of water = 8.624 / 0.997 = 8.65 mL

d) Volume of gold = 8.65 - 5.3

Volume of gold = 3.35 mL

e) Density of gold = Mass / Volume = 60.278 / 3.35

Density of gold = 17.99 g/mL

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