Experiment 2: Laboratory Techniques and Measurements Essay

1705 Words Sep 28th, 2012 7 Pages
Experiment 2: Laboratory Techniques and Measurements

Course Number: CHE 111

Abstract: This experiment introduced the student to lab techniques and measurements. It started with measuring length. An example of this would be the length of a nickel, which is 2cm. The next part of the experiment was measuring temperature. I found that water boils around 95ºC at 6600ft. Ice also has a significant effect on the temperature of water from the tap. Ice dropped the temperature about 15ºC. Volumetric measurements were the basis of the 3rd part of the experiment. It was displayed during this experiment that a pipet holds about 4mL and that there are approximately 27 drops/mL from a short stem pipet. Part 4 introduced the student to measuring
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It used mass, temperature, length, volume, density, and making a dilute solution. I learned the importance as well as the difficulty of making proper measurements in a lab setting. If one measurement is off, it will throw the entire equation off. This will give either incorrect or inaccurate results.

Questions:
A. Water boils at 100°C at sea level. If the water in this experiment did not boil at 100°C, what could be the reason? The experiment was conducted at 6600ft. Water tends to boil at a lower temperature at higher altitudes.

B. While heating two different samples of water at sea level, one boils at 102°C and one boils at
99.2°C. Calculate the percent error for each sample from the theoretical 100.0°C.
102°C-100°C/100°C*100%=0.02% 99.2°C -100°C /100°C *100%= -0.01%
Percent error = 0.02% and -0.01%

C. An unknown, rectangular substance measures 3.6 cm high, 4.21 cm long, and 1.17 cm wide.
If the mass is 21.3g, what is this substance’s density? 21.3g/17.73cm³=1.20g/cm³

D. A sample of gold (Au) has a mass of 26.15 g. Given that the theoretical density is 19.30 g/mL, what is the volume of the gold sample? 26.15g/19.30g/mL=1.35mL

E. Which method for determining density is more accurate, the water displacement method or the Archimedes’ principle method? Why? The water displacement method is more accurate. The string used to suspend the object in the Archimedes’ Method could