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Tidewater Community College. Chesapeake Campus. 2014 CHM 111 Lab 1 This work is licensed under a Creative Commons Attribution-ShareAlike 4.0 International License.

Chesapeake Campus – Chemistry 111 Laboratory

Lab #1 –Fun with Dimensional Analysis

Objectives

Convert numbers from regular notation to scientific notation.

Perform calculations to the correct number of significant figures.

Perform calculations using numbers with SI units.

Convert between base units and units containing prefixes.

Perform calculations using dimensional analysis.

Become acclimated with common laboratory equipment

Introduction

Scientific Notation

Scientific notation is a way to express numbers. It is especially useful for numbers that are very large or very small. In addition, it uses only significant figures, which is helpful for understanding error (see below). In scientific notation, a number is presented containing two components: a coefficient and the number 10 raised to a power. The coefficient contains a single nonzero number to the left of the decimal space.

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As an example, consider the speed of light: 299,000,000 m/s. We would write this as 2.99 x 108 m/s in

scientific notation. The coefficient is 2.99 and must be a number greater than or equal to 1 and less than 10 (one non-zero number will be to the left of the decimal space). The power of 10 is raised to the exponent 8 because you would have to multiply 2.99 by 10

8 to get the correct number. You can also think

about the 8 being from the number of spaces you moved the decimal space. There is an understood decimal at the end of 299,000,000 that we need to move to the right of the number 2 (to allow only a single digit to the left of the decimal). The seven is a positive integer because the number is very large.

2 9 9, 0 0 0, 0 0 0

0 . 0 0 0 0 0 3

Alternatively 0.000003 m is also difficult to express without scientific notation. In order to convert this number to we move the decimal to behind the 3 (the first nonzero number) and add the power of 10 (here we moved the decimal 6 times so the exponent is -6) 3 x 10

-6. Here the exponent is negative because

the number is very small (less than 1). Scientific notation is sometimes referred to as exponential notation.

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Significant Figures

Significant figures are an indication of accuracy and precision within a measurement. All calculations in lab should be done to the appropriate number of significant figures. When measuring something in lab, include all known numbers and one estimated number. For example if the meniscus in lab falls halfway between the 21.0 and 21.2 mL marks we know the digits 21 are known. We have to estimate the decimal space because we only know it is larger than 21.0 and smaller than 21.2. Therefore we could say the estimated mark is at the .1 position giving a volume of 21.1 mL. This gives us two numbers we know and one we have estimated or three significant figures. We could not say it was 21.08 mL because that would be two estimated digits instead of one. Numbers are significant if they meet one of the following criteria.

All non-zero numbers are significant. For example, 87 has two significant figures, while 642.45 has five significant figures.

Zeros sandwiched between two non-zero numbers are significant. Example: 608.5 has four significant figures.

Leading zeros (zeros at the beginning of very small numbers (numbers < 1) are not significant. For example, 0.038 has two significant figures.

Trailing zeros are only significant in a number with a decimal. For example 100 has only 1 significant figure. 100.0 has 4 significant figures. 0.01 has one significant figure because there are no trailing zeros after the 1, but 0.010 has 2 significant figures.

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Significant Figures in Calculations

When multiplying or dividing, your answer should have the same number of significant figures as the number in the calculation with the FEWEST.

When adding or subtracting, your answer should go to number of decimal spaces as the one in the calculation with the FEWEST number of decimal spaces.

A Guide to Solving Dimensional Analysis Problems

The following summary can be used as a guide for doing DA. While not all steps listed below will be

necessary to solve all problems, any problem can be solved using the following. Do not memorize the

sequence of steps, but rather complete practice until you understand how to solve these problems.

Dimensional analysis is a fundamental part of chemistry and will be applied all semester. It is imperative

you gain an understanding of how to perform calculations using dimensional analysis.

1. Determine what you want to know. Read the problem and identify what you're being asked to figure out, e.g. "how many milliliters are in 1 liter of solution."

a. Find starting and ending units:

We are looking for mg in L which means we begin with L and end with mL. You may want to draw out the step(s) you will need for this conversion.

L mL



1L

1L

1000 mL 1000 mL

2. Determine what you already know. a. What are you given by the problem, if anything? Example we know we have 1 liter of

solution. b. Determine conversion factors that may be needed and write them in a form you can use,

such as "60 min/1 hour." Here we would need 1 L = 1000 mL Which we can write as a fraction

1L or 1000 mL

1000 mL 1L

3. Setup the problem using only what you need to know. a. Pick a starting factor.

If possible, pick what is given, but make sure it is in the appropriate location (top or bottom depending on the final units you want).

b. Set up the problem with all units and making sure conversion factors allow units to cancel. Set up the problem to cancel unwanted units.

Our plan is to go to from L mL Using 1 L = 1000 mL

c. If you can't get to what you want, try picking a different starting factor, or checking for a needed conversion factor.

4. Solve: Make sure all the units other than the answer units cancel out, and then do the math.

a. Simplify the numbers by cancellation. b. Multiply all the top numbers together, then divide into that number all the bottom numbers. c. Double check to make sure you didn't press a wrong calculator key by dividing the first top

number by the first bottom number, alternating until finished, then comparing the answer to the first one. Miskeying is a significant source of error, so always double check.

d. Round off the calculated answer. Make sure you use the appropriate number of significant figures.

e. Add labels (the answer unit) to the appropriately rounded number to get your answer. Compare units in answer to answer units recorded from first step.

5. Take a few seconds and ask yourself if the answer you came up with makes sense. If it doesn't, start over.

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Mega

hecto Base Unit = meter, liter, or gram

deka

BASE UNIT

deci

centi

mili

SIZE OF UNIT

micro

nano

DIRECTION OF DECIMAL

Factors of ten 6 3 2 1 0 -1 -2 -3 -6 -9

(no. of decimal

places)

Conversion Examples:

1 kilometer = 1000 meters (decimal moved 3 places to the right)

10 liters = 10 000 mililiters (decimal moved 3 places to the right)

2.5 centimeters = 0.025 meters (decimal moved 2 places to the left)

1 microgram = 1000 nanograms (decimal moved 3 places to the right)

5 meters = 5 000 000 000 nanometers (decimal moved 9 places to the right)

METRIC SYSTEM CONVERSION GUIDE

Guides Significant Figures – Rules

Significant figures are critical when reporting scientific data because they give the reader an idea of how well you could actually measure/report your data. Before looking at a few examples, let’s summarize the rules for significant figures.

1) ALL non-zero numbers (1, 2, 3, 4, 5, 6 ,7, 8, 9) are ALWAYS significant. 2) ALL zeroes between non-zero numbers are ALWAYS significant. 3) ALL zeros which are SIMULTANEOUSLY to the right of the decimal point AND at the

end of the number are ALWAYS significant. 4) ALL zeros which are to the left of a written decimal point and are in a number > 1 are

ALWAYS significant.

A helpful way to check rules 3 & 4 is to write the number in scientific notation. If you can/must get rid of the zeros, then they are NOT significant. Examples: How many significant figures are present in the following numbers?

NUMBER # SIGNIFICANT FIGURES RULE(S)

48,923 5 1

3,967 4 1

900.06 5 1, 2, 4

0.0004 (=4 E-4) 1 1, 4

8.1000 5 1, 3

501.040 6 1, 2, 3, 4

3,000,000 (=3 E+6) 1 1

10.0 (=1.00 E+1) 3 1, 3, 4

Metric System Conversions

kilo



THE METRIC SYSTEM

Root Decimal Power of

Prefix Abbreviation (1 with prefix = ___ base) Ten

Mega M 1 000 000 106

kilo k 1 000 103

hecto h 1 00 102

deka da 1 0 101

meter m 1 100

The Basic

liter L 1 Metric 100

Units

gram g 1 100

deci d 0.1 10 - 1

centi c 0.01 10 - 2

milli m 0.001 10 - 3

micro μ 0.000 001 10 - 6

Metric Step Conversions

Mega

======

kilo

hecto

deka

m, L, g (base unit)

deci

centi

milli THE NUMBER OF STEPS = THE

NUMBER OF FACTORS OF

10 DIFFERENCE BETWEEN

micro THE PREFIXES



References

1. Selection modified from: Boundless Scientific Notation 2014 CC-BY-SA 3.0

https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/introduction-to-chemistry-

1/measurement-uncertainty-30/scientific-notation-187-3705/

2. Selection modified from: Boundless Significant Figures 2014 CC-BY-SA 3.0

https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/introduction-to-chemistry-

1/measurement-uncertainty-30/significant-figures-188-7529/

3. Selection modified from: Mrs. Patton 2014 CC-BY-SA Dimensional Analysis with Samples http://math-

mrspatton.wikispaces.com/file/links/Dimensional+Analysis+with+Samples.doc

4. Selection modified from: RHolding SI Unit Conversions 2014 CC-BY-SA http://holding-

livingenvironment.wikispaces.com/file/detail/SI+Unit+Conversions.doc

5. Selection modified from: Mrs. Ermann Dimensional Analysis Problems 2014 CC-BY-SA

https://mrsermann.wikispaces.com/file/detail/Dimensional+Analysis+Problems.doc


https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/introduction-to-chemistry-1/measurement-uncertainty-30/scientific-notation-187-3705/

https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/introduction-to-chemistry-1/measurement-uncertainty-30/scientific-notation-187-3705/

https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/introduction-to-chemistry-1/measurement-uncertainty-30/significant-figures-188-7529/

https://www.boundless.com/chemistry/textbooks/boundless-chemistry-textbook/introduction-to-chemistry-1/measurement-uncertainty-30/significant-figures-188-7529/

http://math-mrspatton.wikispaces.com/file/links/Dimensional+Analysis+with+Samples.doc

http://math-mrspatton.wikispaces.com/file/links/Dimensional+Analysis+with+Samples.doc

http://holding-livingenvironment.wikispaces.com/file/detail/SI+Unit+Conversions.doc

http://holding-livingenvironment.wikispaces.com/file/detail/SI+Unit+Conversions.doc

https://mrsermann.wikispaces.com/file/detail/Dimensional+Analysis+Problems.doc


Materials

Student tray containing the following: o 1-250mL beaker (with measurement lines printed on side) o 1-50mL beaker (with measurement lines printed on side) o Thermometer o 1-50 mL graduated cylinder o Weight boat o Paper clip o Pipet o DI water bottle o Supply beaker with disposable items: pipettes, scoopula, small weigh boat, parafilm. o Container of glassware soap and a brush in a beaker labeled “Waste.”

Balance

Safety and Notes

Additional materials that will be used throughout the semester can be found in your student drawer to include:

Drawers:

• green pipet pump

• 2 rolls of labeling tape

• test tube holder

• 1 striker

• 1 sharpie

• 1 rubber “hot hand” mitt (every other drawer)

• 1 glassware tongs

• 1 beaker tongs

• 1 ruler

• 1 long handled deflagrating spoon

• 1 goggles

• Components for ring/support stand

• Mesh/gauze square

• Clay Triangle

• Ring

• Test tube Clamp with vinyl coating

• Titration/thermometer clamp with fingers or test tube clamp w/vinyl coating(either one in every other drawer)

• Mat glued to drawer Cabinet:

• Test tube rack

• Hot plate

• Bunsen burner with gas line Benchtop:

• Ring support stand to be shared with group of 4 with titration clamp

Wear safety goggles at any time any group is performing the experiment.

Inspect all equipment for damage. Broken or chipped glassware should be reported and placed into glass container.

The balance should be in the lock position during transport. When ready to use unlock the balance by turning it over and finding the switch. Use the balance in the unlocked position when weighing. At the end of the lab switch it back to the lock position and return to the cart.

Waste water for today’s lab can be disposed of down the drain at your station.

Return all trays with in order with clean, dry glassware and items and place on cart.

Please, please return all # materials to the proper # drawers and # trays.



Name ____________________________________________ Date ________________

Lab Partner Name___________________________________ Bin #________________

Pre-lab Assignment/Questions

N o t e – this pre-lab must be finished before you come to lab.

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

Measurement Unit Symbol

1. Length Meter

2. Mass kg

3. Volume L

4. Temperature Kelvin

5. Second s

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

Base Unit Prefix Conversion Factor Numerical form

Conversion Factor Scientific Notation

EX. Meter (m) Milli (m) 1 m = 1000 mm 1 m = 103 mm

6. Liter (L) 1 L = 1,000,000 μL 1 L = 106 μL

7. Seconds (s) Centi (c) 1 s = 100 cs

8. Grams (g) Kilo (k) 1 g = 10 - 3 kg or

1000 g = 1 kg

9. Meter (m) Nano (n) 1 m = 1,000,000,000 nm

10. Mol (mol) Milli (m) 1 mol = 103 mmol



Name ____________________________________________ Date ________________


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 __________________

3. Height (measure internal height only). ________________

4. Using a ruler and a beaker to determine the volume of solution the beaker can hold. V = πr2h

(Remember that cm3 = 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?



Name ____________________________________________ Date ________________


Experimental Data and Results

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.



Name ________________________________________________ Date __________________

Lab Partner ____________________________________________ Bin # __________________

PostLab Questions

*Solve the following problems using dimensional analysis. Remember to label the units in every

conversion factor, include the appropriate units in your final answer, and round for significant figures.

Work must be shown for full credit. Remember, you are expected to memorize your metric prefixes

and their associated conversion factors. Other ones you might need are included in the problems

(you may have to refer back to previous problems). Others should be well-known facts. 3, 5

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 103 mL to L.

9. Convert 25 cm to mm.

10. Convert 0.075 m to cm.

11. Convert 15 kg to mg.



Name ________________________________________________ Date __________________

Lab Partner ____________________________________________ Bin # __________________

PostLab Questions

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 7.3x10-3 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 = 1.43x10-4 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.)*


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