pre laboratory assignment chemistry answers

Module 1: Fun with Dimensional Analysis

Lab 1 worksheet, pre-lab assignment.

Note: this pre-lab must be finished before you come to lab.

Fill in the blanks on the following table using appropriate SI units:

Fill in the blanks on the following table giving commonly used conversion factors:

Experimental Data and Results

*Be sure to answer all questions using the correct number of significant figures. Include all work, units and write answers in scientific notation (if applicable) for full credit.

1. Obtain a thermometer and record the temperature of the room to the correct number of significant figures.

Use a ruler from your drawer to determine the dimensions of a 250 mL beaker. Make sure you use the appropriate number of significant figures. You must show all calculations and units for full credit.

2. Diameter _________________ Radius __________________

4. Using a ruler and a beaker to determine the volume of solution the beaker can hold. V = πr 2 h (Remember that cm 3 = mL)

5. Why does the beaker capacity exceed the volume printed on the side?

6. Compare the graduated cylinder to the beaker. Which will make the more accurate measurement? Why?

7. Obtain a 50 mL beaker and fill to the 30.0 mL mark using DI water. Make sure you remember to read from the bottom of your meniscus line. Pour this entire amount into your 50 mL graduated cylinder. Read the volume again (using your meniscus). Do not pour out. Record result. ______________________________

8. Using the balance, place a weight boat on the balance and tare or zero. Add the paperclip and record the weight in grams. __________________________. Convert this weight to milligrams ________________________.

9. Again place the weight boat on the balance and tare. Obtain a pipet bulb from your drawer. Using the DI water from your graduated cylinder and a pipet, draw 1mL of DI water by rolling the wheel allowing the water to fill to the mark. Transfer the entire contents of the pipet to the weight boat to determine the mass. Record your results ____________________________. Did 1 mL of water = 1g? Explain your findings.

10. Convert your above result from grams to milligrams.

Post-Lab Questions

1. How many centimeters are in three meters?

2. A line 20 millimeters long is how many centimeters long?

3. If a student is one meter tall. What is its height in kilometers?

4. How many milliliters are in a two liter bottle?

5. Convert 3.25 centimeters into kilometers

6. Convert 950 g to kg.

7. Convert 275 mm to cm.

8. Convert 1.0 x 10 3 mL to L.

9. Convert 25 cm to mm.

10. Convert 0.075 m to cm.

11. Convert 15 kg to mg.

12. Convert 3.25 hours to seconds.

13. Convert 2.5 yards to inches. (Remember, there are 3 feet in 1 yard.)

14. Convert 1.2 years into hours. (Remember, there are 365 days in 1 year.)

15. How many centimeters are in 50,555 micrometers?

16. Convert 7.3 x 10 -3 km to m.

17. Convert 67.5 millimoles to moles

18. An average human lives to be 70 years old. How many seconds would have elapsed during this person’s lifetime?

19. The usual aspirin tablet contains 5.00 grains of aspirin. How many mg of aspirin are in one tablet? (Remember 1 grain = 1.43 x 10 -4 lb, 1 lb = 454 g.)

20. How many 3 oz oranges would you need to eat to meet the U.S. recommended daily allowance of 60.0 mg of vitamin C, if there are 70 mg of vitamin C for every 100 g of orange? (Remember, 16 oz = 454 g.)

• College Chemistry 1 . Authored by : Jessica Garber-Morales . Provided by : Tidewater Community College . Located at : http://www.tcc.edu/ . License : CC BY: Attribution

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8.1: Pre-lab Assignment

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• Page ID 425146

• Kathryn Haas
• Duke University

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Please complete the general pre-lab assignment.

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• Advancing Your Skills

Pre-Lab Assignments

For students in lab courses, nothing feels more pointless than just going through the motions of a lab procedure without understanding why it is significant. Emphasize to students that experimental science is the basis for the models they learn about in lecture. Lab, unlike lecture, represents professional science in practice. Lab also represents a playground where curiosity is sparked and scientific theories are put to the test. If students recognize this, they will gain a better understanding of what science truly is and may be more motivated in their lab work.

Preparing students for lab involves the following:

• Helping students understand the models, theories, and principles addressed in the lab procedure — giving them a conceptual framework for the lab
• Ensuring that students know how the lab fits into the course content
• Outlining the lab procedure and data analysis
• Orienting students to the relevant equipment and safety procedures

A well designed pre-lab assignment can serve all these functions. Pre-lab assignments are tasks or homework that students complete before arriving in class for the lab period. Pre-lab assignments motivate students to prepare for the lab and help them connect conceptual understanding with an experiment.

There are several advantages for students in using a pre-lab assignment:

• Students come better prepared for the lab exercise.
• Experiments and exercises go more smoothly because students are familiar with the processes.
• Their understanding of the material is heightened.

There are advantages for the instructor as well:

• The assignment can streamline the process of writing a  pre-lab introduction .
• The assignment can make it easier to teach the theory behind the lab, since students will have a firmer understanding of the principles behind it.

For many of the lab classes you will teach, the professor may already have pre-lab assignments written for you to give your students. However, in cases where there are no pre-lab assignments written into the course already, you may choose to create and implement your own.

Designing a Pre-Lab Assignment

Concepts and types of questions.

First, think about the models and questions you feel are important to address in a pre-lab assignment. What do you want your students to have understood or thought about before they arrive in lab?

In order to help students frame the lab experiment, consider the main question your students should become able to answer:

• What question is this lab experiment answering?
• How will your data answer this question?
• How will you collect this data?
• How will you minimize ambiguity and control variables?

Here are some of the topics you might ask your students to think about in a pre-lab exercise:

• concepts, theory, and models
• procedure and methods (for an example see the Teaching Effectiveness Award essay by Jessica Smith [Chemistry],  A Pre-Lab Assignment for a More Efficient and Effective Laboratory )
• troubleshooting and other experimental issues
• prediction of trends in data or other qualitative questions about data
• quantitative questions such as calculations with simulated data
• interpretation of simulated results

Linking to the Pre-Lab Introduction

It is important to consider how you will introduce the lab on the day of the lab section. It is most common to give a short  pre-lab introduction .

• Connecting the questions and concepts addressed in your pre-lab assignment with those that you plan to address in your pre-lab introduction helps make certain that these two aspects of lab preparation complement each other.
• Use discussion of the pre-lab assignment as a starting point for the pre-lab introduction and as a tool for introducing the lab. In fact, you should go over at least some part of the pre-lab assignment at the beginning of the lab period. This ensures that students have understood the material and concepts therein before the lab exercise begins.

Here are several ways that you may format your pre-lab assignment, each with advantages or disadvantages depending on the material, your class, and the outcomes you wish to achieve from the assignment:

• Worksheet done before lab  (handed in at the beginning of lab): This format works well if you can create well-defined questions to help your students consider some theory or concepts related to the lab. Sometimes giving students sample calculations, data, or experiments on a worksheet is also helpful, if the lab material lends itself to this approach.
• Assignment worth a few points  (handed in at the beginning of lab): This is useful when preparing for the lab requires students to research information on their own. You can also make this a small group assignment that a lab group or lab partners can do together to prepare for lab or to think about important concepts relating to the lab.
• Quiz at the start of lab : This is most useful if you want to ensure your students are preparing for lab on their own by reading the lab or background materials in advance. Again, it works well if the quiz can function as a starting point for discussion or an introduction to the lab.
• Preparation of lab notebook  (checked at the start of lab): This can work well if having a comprehensive lab notebook is crucial to the students’ understanding of the lab material (anatomy courses, involving dissections and labeling structures, are one example). Checking the students’ lab notebooks can help confirm that students are making the best use of their lab time and taking away the most valuable information from the lab. It also is an incentive for students to organize their lab material well, thus maximizing the benefits of the lab period.
• Quiz on the web to be completed before class  (currently implemented in Chemistry 1A at UC Berkeley): Pre-lab web quizzes can be an excellent way to use technology to help your students prepare for lab. Having students take the quiz on the web before class will alert you to problems that students are having in understanding lab material. You can then take this into consideration when introducing the lab on the day of section.