  # Basic Measuring Devices

Written by Kassandra

Objective:

The objective of this experiment was to learn about the different measuring devices that are used in a Chemistry lab, such as volume devices and electronic balances. In addition, to learn how to record measurements correctly.

Methods:

The first part of our lab was to read and record the right volume of different measuring devices we had on our lab bench. This was to unsure that we could record measurements correctly with the correct number of significant figures.

The second part of the experiment was to learn how to use the devices correctly by first doing our experiment with water. The ultimate goal was to determine the density of our unknown substance by finding the mass. We first started with water so we could learn how to properly use the scale and the pipet so that we could get more accurate results by using the tools properly.

The last part was doing the same measurements, only with our unknown, after we found the mass of our unknown; we were about to find the density. Density= mass/volume.

Data:

Bench #1        Unknown #6

Table 1: Volume readings on different volume devices.

 Graduated Beaker (mL) Graduated Cylinder (mL) Graduated Pipet (mL) Buret (mL) Thermometer (°C) Total Volume or Temp 100.mL 50.0mL 10.00mL 50.00mL 150°C Smallest Scale 10.mL 1mL .1mL .1mL 1°C Precision 1mL .1mL .01mL .01mL .1°C Reading of the device 50.mL 23.8mL 6.80mL 38.2mL 20.5°C

Table 2: Mass of Water

 Mass, Empty 50mL beaker Mass, Beaker and 10.00mL and water Run 1 28.27g 38.07g Run 2 28.29g 38.24g

Table 3: Mass of Unknown

 Mass, Empty 50mL beaker Mass, Beaker and 10.00mL and unknown Run 1 28.30g 38.20g Run 2 28.52g 38.33g

Calculations:

1.Mass of 10 mL of water for each run

Run 1: 38.07-28.27= 9.80g

Run 2: 38.24-28.29= 9.95g

2. Average Mass of water

(Run 1+ Run2)/2= Average

(9.95+9.80)/2=9.88g

3. Mass of Unknown for each run

Run 1: 38.20-28.30= 9.90g

Run 2: 38.33-28.52= 9.81g

4. Average mass of unknown

(Run 1+ Run2)/2= Average

(9.90+9.81)/2 =9.86g

5. Density of water:

Density= mass/volume

D=9.86/10.00

D=.99g/mL

6. Density of unknown:

Density= mass/volume

D=9.95g/10.00mL

D=.995g/mL

7. Percent Error for unknown

Percent Error= (result- accepted value/accepted value) x100

P.E= (.995- 1.0188/1.0188) x 100

P.E= -2.33% à 2.33%

Discussion Questions:

1. Accuracy is how close to the real measurement your own measurement is. Precision is how close the measured values from your trials are to each other.

2. Density is not constant in all states of matter. A few elements and compounds, such as water, have a different density depending on what state they are in.

Discussion of Results:

In this experiment, we ultimately were trying to find the density of the unknown while learning the different measuring devices in the lab. It was challenging to use new equipment and read the devices while trying to be accurate in our measurements. For me, the hardest equipment was the pipet; it was a completely new device that was hard to get used to.

Our calculating concluded that we had an error of 2.33%, which is very close to the actual value. Error could have occurred while getting used to the pipet, or being slightly off with measurements.

Conclusion:

In conclusion, I was able to calculate mass and volume using the different measuring devices in the Chemistry Lab. By using these devices, I found the density of our unknown liquid.

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