Experiment 2: Laboratory Techniques and Measurements

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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 mass using an electronic scale. Step 5 was about density measurements. If you have an objects mass and volume, you can divide the mass by the volume to get the density. Step 6 was the introduction and use of the water displacement method, Archimedes’ Method, and the math calculation method. The water displacement method uses the volume displaced by the object and the mass of the object to identify the density. Archimedes’ Method identifies the density by using the mass and the weight of the volume displaced by the object. The math calculation method uses the measured volume of the object and the mass to calculate the density of the object. The final part of the experiment was just an introduction to a lab technique. It was how to make a dilute solution using a 2mL pipet and a 25mL volumetric cylinder.

Experiment and observation: Measure Length, Temperature, Volume, and Mass. After calculating mass and volume, determine density using D=M/V.

Data Table 1: Length Measurements|
Object|Length (cm)|Length (mm)|
AA Battery|4.8cm|48cm|
Clothes Pin|7.8cm|78mm|

Data Table 2: Temperature Measurements|
Hot Water from Tap(ºC )|Boiling Water(ºC )|Boiling Water-5Minutes(ºC )| 51 ºC|95 ºC|97 ºC|
Cold Water From Tap(ºC )|Ice Water(ºC )|Ice Water-5Minutes(ºC )| 19 ºC|9 ºC|4 ºC|
Data Table 3: Volumetric Measurements|
Test tube volume (mL)|Number of drops in 1 mL|Pipet volume (mL)| 9mL|27drops/mL|4mL|

Data Table 4: Mass Measurements|
Object|Estimated Mass (g)|Actual Mass (g)|
AA Battery|15g|23.7g|
Clothes Pin|8g|5.5|
Tungsten Wedding Band|7.5g|9.7g|
Steel BB|2g|2.1g|
Army ID Tag|3g|4.1g|

Data Table 5: Density Measurements|
||Mass A|Mass B|Mass A - B|||
Object|GraduatedCylinder +Substance|GraduatedCylinder|Substance|SubstanceVolume||DensityM/V| Water|21.4g|16.5g|4.9g|5mL||0.98g/ml|
Isopropyl alcohol|21g|16.5g|4.5g|5mL||0.9g/mL|
Saturated saltsolution|22.5g|16.5g|6g|5mL||1.2g/mL|

Hypothesis: I assumed the salt solution would weigh more due to the addition of the NaCl being suspended in the water as a solution.

Data Table 6: Densities of Irregular Objects|
Object|GraduatedCylinderVolume|GraduatedCylinder +Object|ObjectVolume|ObjectMass||DensityM/V| Metal bolt - Waterdisplacement method|12.5mL|13.5mL|1.0mL|8.0g||8.0g/mL| Metal bolt - Archimedes’Method|||1.0cc|8.0g||8.0g/cc or 8.0g/mL| Magnet - Waterdisplacement method|12.5mL|13.5mL|1.0mL|4.6g||4.6g/mL| Magnet - Archimedes’Method|||1.0cc|4.6g||4.6g/cc or 4.6g/mL| Magnet - Math calculationMethod|||1.27cm³|4.6g||3.62g/cm³|

Making a Dilute Solution

This part of the experiment was used to introduce the student to the use of a pipet to make a solution in a known volume container. It took some practice to get the technique just right in order to make the proper amounts.

Calculations and error: There were several ways to make errors and incorrect calculation during this experiment. Mathematical error in an equation is one. I had a problem making consistent drops with the pipet. I’m sure that messed with some of my measurements. Measuring out the mass of salt also proved to be problematic for me. It is almost impossible to just pour salt onto the...
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