Vapor pressure at 220 C : 2.6447
Trial 1:
Lenght of Magnesium ribbon used: 2.2 cm
Mass of Magnesium Ribbon used: 0.02784375 g.
Volume of H2(after the reaction): 29.5 cm3
Volume of MgCl2(aq): 20.5 cm3
Volume of H2(in the big beaker, 1 atm) : 29.1 cm3
Volume of MgCl2(aq)(in the big beaker): 20.9 cm3
Trial 2:
Lenght of Magnesium ribbon used: 2.2 cm
Mass of Magnesium Ribbon used: 0.02784375 g.
Volume of H2(after the reaction): 29.0 cm3
Volume of MgCl2(aq): 21.0cm3
Volume of H2(in the big beaker, 1 atm) : 29.4 cm3
Volume of MgCl2(aq)(in the big beaker): 20.6 cm3
Trial 3:
Lenght of Magnesium ribbon used: 3.6 cm
Mass of Magnesium Ribbon used: 0.0455625 g.
Volume of H2(after the reaction): 34.2 cm3
Volume of MgCl2(aq): 15.8 cm3
Volume of H2(in the big beaker, 1 atm) : 33.9 cm3
Volume of MgCl2(aq)(in the big beaker): 16.1 cm3
Calculations:
101500 – 2.6447 = 101497.4 (pressure of air minus vapor pressure)
Trial1:
(2.2 x 0.81) / 64 = 0.02784375 / 24.31 = 0.001145 mol Mg
(101497.4 x 0.0291) / (295 x 0.001145) = (101000 x V) / 273
8744.206469 = (101000 x V) / 273
V = 23.6 dm3
(23.6 – 22.4) / 22.4 = 0.0536 x 100 = % 5.36
Trial 2:
(2.2 x 0.81) / 64 = 0.02784375 / 24.31 = 0.001145 mol Mg
(101497.4 x 0.0294) / (295 x 0.001145) = (101000 x V) / 273
8834.352927 = (101000 x V) / 273
V = 23.9 dm3
(23.9 – 22.4) / 22.4 = 0.067 x 100 = % 6.7
Trial 3:
(2.6 x 0.81) / 64 = 0.03290625 / 24.31 = 0.001354 mol Mg
(101497.4 x 0.0339) / (295 x 0.001354) = (101000 x V) / 273
8614.179856 = (101000 x V) / 273
V = 23.3 dm3
(23.3 – 22.4) / 22.4 = 0.0402 x 100 = % 4.02
Processed Data:
Trial 1:
Calculated Molar Volume of a gas in STP: 23.6 dm3
Mass of Mg Used: 0.02784375 g. Mg
Mole of Mg used: 0.001145 mol Mg.
Trial 2:
Calculated Molar Volume of a gas in STP: 23.9 dm3
Mass of Mg Used: 0.02784375 g. Mg
Mole of Mg used: 0.001145 mol Mg.
Trial 3:
Calculated Molar Volume of a gas in STP: 23.3 dm3
Mass of Mg Used: 0.03290625 g. Mg
Mole of Mg used: 0.001354 mol Mg.
Conclusion: The results were found by using boyle’s and Charles’s laws. The accepted value of the molar volume of a gas at STP is 22.4 dm3. The most accurate trial was the Trial 3, because the percent error of Trial 3 is the smallest. (% 4.02). The average result of 3 trials is 23.6 dm3 and the percent error for the average value is % 5.36.
Evaluation: One source of error is, the aqueous solution of MgCl2 was mixed up with water so it could effect the vapor pressure. Also when equalizing the levels of both liquid in the big beaker the level of MgCl2 couldn’t be seen precisely. Also there was air inside of the gas measuring tube because of the hole in the rubber stopper. To achieve better results, the hole on the rubber stopper could be filled with water. The water inside of the big beaker could be changed after every trial to at least lessen the amount of MgCl2 solution in the water. The level of the water can be seen more precisely if the gas measuring tube has different color measuring lines to increase the readability.
