# uncertainty measurement and significant figure

Module 01 Lab 01 – Uncertainty, Measurements, and Significant Figures

Purpose of Experiment: To become familiar with the virtual lab software, solutions, glassware and tools available. To gain a better understanding of uncertainty, how to take measurements and how to report significant figures properly.

Chemicals and Materials:

Distilled H
2O

5 mL Pipette

250 mL Beaker

Scale

Solid Sodium Chloride

Weigh Boat

Deliverables:

• Record of all observations.
• Calculations for conversions, scientific notation, and significant figures.

Instructions for Virtual Lab: Record all observations.

Go to lab page: http://www.chemcollective.org/vlab

1. From the stockroom in the Virtual Lab, obtain glassware, solutions/solids, and a scale.
2. Fill the 250 mL Beaker using the realistic tab with approximately 200 mL of H2O.
3. Using the 5 mL Pipette and the realistic tab, draw up approximately 5 mL of water.
4. Using the realistic tab, press the hold to pour button until you have dispensed at least 2 mL of water into the graduated cylinder.
5. Reading the meniscus, record and report with the correct significant figures the volume of liquid dispensed.
6. Obtain the scale and a 250 mL Flask.
7. Place the flask on the scale and record the weight of the flask.
8. Using the â€œtareâ€ button, tare the weight of the flask, pour the water from the graduated cylinder into the flask and record the weight of the water to the three significant figures.
9. Remove all items except the scale from the workbench.
10. Obtain a weigh boat from the stockroom glassware under other.
11. Place the weigh boat on the scale and record its weight.
12. Tare the weight of the weigh boat.
13. Obtain the NaCl (sodium chloride) from the stockroom solutions under solids.
14. Using the realistic tab, transfer two scoopulas full onto the weigh boat and record the weight of the sodium chloride with three significant figures.

Instructions for Calculations: Complete the following calculations for conversions, scientific notation, and significant figures.

Convert the following:

1. 23 yd. =___ m
2. 4 km =____ mi
3. 78 kg =____ lbs.
4. 4 g =___ oz.
5. 5.3 gal =____L

Convert following numbers into or out of scientific notation:

1. 20,452,384
2. 3 x 103
3. 0.03498
4. 0.00004928
5. 2.983 x 10 -4

Perform calculations and report answers with correct significant figures. Use scientific notation when needed.

1. 2.04 + 0.334 =
2. 20.33 â€“ 0.2 =
3. 409 x 22.44 =
4. 3.0/29 =
5. 29,004 x 2.0 =
6. (2.6 â€“ 0.67) x 4.0 =
7. 4.1(3.8 â€“ 0.04)/3.46 =

Module 01 Lab 02 – Metals Density Problems

Purpose of Experiment: To explore how to find the density of metals by the displacement method.

Deliverables:

• Data Sheet containing recorded observations and calculations
• Screenshot of completed lab

Instructions:

For this lab assignment, you will need to read the instructions for the Metals Density Problem on the ChemCollective website. After you complete this reading, return to this assignment to read step-by-step instructions about how to actually complete the lab on the ChemCollective page.

To complete the lab assignment, complete the following steps within the virtual lab:

1. Create a data sheet to record all data and calculations.
2. Obtain a 250 mL beaker and fill with water from the stock solution of water available. (This will be used to find the density of all three metals). The stock solution of water can be removed from the workbench once water is added to the beaker.
3. Obtain metal 1 from the stockroom and notice the approximate volume needed (found in the information tab).
4. Obtain a graduated cylinder that is larger than the approximate volume needed (if the needed volume is 10 mL, obtain a 25 mL graduated cylinder; if needed volume is 20 mL, obtain a 50 mL graduated cylinder).
5. Using a pipet (use appropriate size pipet for volume needed), transfer water from the beaker to the graduated cylinder.
6. Record volume transferred.
7. Obtain the scale from the stockroom.
8. Obtain a weigh boat from the stockroom (found under glassware).
9. Place weigh boat on scale, record weight displayed.
10. Tare weight displayed (click tare button on scale â€“ if this button does not work, then continue with next step. Make sure you have recorded weigh boat weight, so you can subtract it to determine weight of metal).
11. Pour metal 1 onto weigh boat and record weight of metal 1 added to weigh boat.
13. Record amount of metal added.
14. Record new volume.
15. Calculate the density of the metal and record.
16. Repeat for metal 2 and metal 3.
17. Identify the correct metal in provided boxes in virtual lab.
18. Take a screenshot of completed virtual lab page. For assistance taking a screenshot, refer to the following guide.
19. Submit the screenshot along with the data sheet.

Module 01 Assignment

Following the instructions within the document, complete the assignment. This assignment will help you to practice the concepts presented in the lecture and prepare for this module’s quiz.