Regular Chemistry Name: ____________________________ #______

Block: __________

Unit 1: Intro to

Experimental Practice

Worksheet Packet

Worksheet Due Date1 Experimental Design WS

2 Sig Fig & Scientific Notation WS

3 Dimensional Analysis WS

4 Accuracy & Precision WS

5 Percent Error WS

Common Unit ConversionsVolume:1 oz = 29.57 mL1 cup = 8 fl. oz1 gal = 16 cups1 gal = 4 quarts1 quart = 2 pints1 pint = 2 cups1 m3 = 106 cm3

Length:1 mile = 5280 feet1 mile = 1609 m1 inch = 2.54 cm

Energy:1 calorie = 4.18 Joules (J)

Weight:1 kg = 2.2 lbs1 ton = 2000 lbs1 kg = 35.27 oz

Pressure:1 atm = 101.3 kPa1 atm = 760 torr1 atm = 760 mmHg

Prefix Conversions

Experimental Design WS (Page 1 of 2)Chemistry

DIRECTIONS: Use each description and/or data table to help you identify or describe: 1) the independent variable, 2) the best dependent variable, 3) at least 3 variables that should be held constant, and 4) the control group in the experiment. Some experiments do not have a clear control. In these cases, the first trial is used as a control. Make sure your answers are specific.

FISH EGGS: A scientist knows that the percent of fish eggs that hatch is affected by the temperature of the water in an aquarium. She is attempting to identify which water temperature will cause the highest percentage of fish eggs to hatch. The scientist sets up 5 aquariums at the following temperatures: 10°C, 20°C, 30°C, 40°C, and 50°C. She adds 50 fish eggs to each aquarium and records the number of eggs that hatch in each aquarium.

Independent Variable(s): _____________________________________________________________________

Dependent Variable: ________________________________________________________________________

List 3 constants: ____________________________________________________________________________

__________________________________________________________________________________________

__________________________________________________________________________________________

Describe the control group in the experiment:

__________________________________________________________________________________________

__________________________________________________________________________________________

SAND AND PEAT MOSS: An environmental agency wants to know if adding peat moss to sand will affect its ability to hold water. A scientist put 200 mL of sand into container A, a mixture of 80% sand and 20% peat moss into container B, and a mixture of 60% sand and 40% moss into container C. After adding 100 mL water to each container, the amount of water the contents absorbed was measured. The mixtures of each container were then dried, and the experiment was repeated five times.

Independent Variable: _______________________________________________________________________

Dependent Variable: ________________________________________________________________________

List 3 constants: ____________________________________________________________________________

__________________________________________________________________________________________

__________________________________________________________________________________________

Describe the control group in the experiment:

__________________________________________________________________________________________

__________________________________________________________________________________________

(Page 2 of 2)MOUTHWASH: The makers of brand A mouthwash want to prove that their mouthwash kills more bacteria than theother 4 leading brands of mouthwash.They organize 60 test subjects into 6 groups of 10 test subjects. The data for the experiment is shown to the right.

Independent Variable: _______________________________________________________________________

Dependent Variable: ________________________________________________________________________

List 3 constants: ____________________________________________________________________________

__________________________________________________________________________________________

__________________________________________________________________________________________

Describe the control group in the experiment:

__________________________________________________________________________________________

__________________________________________________________________________________________

FIRE EXTINGUISHERS: A firefighter is trying to figure out which type of fire extinguisher (CO2, water, or dry chemical) will put out fires the fastest. Think about the issue being tested and imagine an appropriate experiment to determine which type of fire extinguisher can extinguish fires the fastest. Then, identify the key elements of the experimental design listed below.

Independent Variable: _______________________________________________________________________

Dependent Variable: ________________________________________________________________________

List 3 constants: ____________________________________________________________________________

__________________________________________________________________________________________

__________________________________________________________________________________________

Describe the control group in the experiment:

__________________________________________________________________________________________

__________________________________________________________________________________________

mouthwashused

time mouthwashwas in mouth

# of bacteria inmouth (average)

none - 135A 60 sec. 23B 60 sec. 170C 60 sec. 84D 60 sec. 39E 60 sec. 81

Sig Fig & Scientific Notation WS (Page 1 of 1)Chemistry

1. Determine the number of significant figures and convert each of the following into correct scientific notation using 3 significant figures.

Number # of Sig Figs Scientific Notation

3427

0.00456

123453

0.000984

0.502

107.2

0.982 x 103

20.4 x 105

2. Calculate the following providing your answer in the correct number of significant figures.

a. 1.35 x 2.467

b. 1035 / 42

c. 12.01 + 35.2 + 6

d. 55.46 – 28.9

e. 0.021 x 3.2 x 100.1

f. 0.15 + 1.15 + 2.051

g. 150 / 4

h. 1.252 x 0.115 + 0.012

i. (1.278) / (1.4267)

j. (752.12 + 26.3) / 1.02423

Dimensional Analysis WS (Page 1 of 2)Chemistry

Use the following conversions to complete these problems:1 egg = 45 grams (g)

1000 g = 1 kilogram (kg)1 kg = 2.2 pounds (lbs)

1 car = 2000 lbsConvert from the given amount to the amount stated. SHOW ALL WORK, including all ratio’s and cancellation. Include the proper units in your answer

1. Convert 27 eggs to kg

27 eggs x gramseggs

x kggrams

=¿

2. Convert 500 lbs to eggs

500 lbs x x x =¿

3. Convert 500 grams to pounds

500 g x x =¿

4. Convert 3 cars to eggs

3 cars x x x x =¿

5. Convert 3000 grams to cars

3000 g x x x =¿

Perform the following conversions using the dimensional analysis technique. Report your final answer using the correct number of significant figures. If you do not know the conversion, look it up!

1. 2.5 L = gallons(1 gal = 3.785 L)

2. 341 calories = joules (Page 2 of 2)(1 cal = 4.18 J)

3. 0.5000 miles = feet(1 mile = 5280 feet)

4. 18 hours = seconds

5. 10.5 seconds = minutes

6. 12,583 seconds = days

7. 36.7 miles = yards

8. 47.8 inches = cm

9. 131 feet = miles

10. A student goes through seven class periods in school. Each period lasts 55 minutes. How many hours do they spend in class per week?

Accuracy & Precision WS (Page 1 of 1)ChemistryDefinitionsAccuracy – how close a measurement is to the true valuePrecision – how close a set of measurements are to each other

Precision vs. Accuracy

Given the following sets of data, calculate the average and circle to indicate whether the data set is accurate, precise, both, or neither. The average should be in the same number of sig figs as the data provided.

1) An object is 1.00 meters long. Average: __________ 1.151.10 Accurate Precise Both Neither1.121.30

2) An object is 50. cm long. Average: __________5260. Accurate Precise Both Neither4841

3) An object has an area of 15.00 cm2. Average: __________13.2113.22 Accurate Precise Both Neither13.2013.22

4) An object has a density of 0.31 g/mL. Average: __________0.300.32 Accurate Precise Both Neither0.310.31

5) An object has a volume of 27.0 mL. Average: __________

27.533.0 Accurate Precise Both Neither21.822.8

Percent Error WS (Page 1 of 1)Chemistry

% Error=|Theoretical value−Experimental valueTheoretical value |x 100 %

Find the percent error for each of the following:1) Experimental Value: 1.24 g Accepted Value: 1.30 g

Answer: _______________2) Experimental Value: 125.2 mg Accepted Value: 124.8 mg

Answer: _______________3) Experimental Value: 1.24 x 10-2 g Accepted Value: 9.98 x 10-3 g

Answer: _______________4) Joshua uses his thermometer and finds the boiling point of ethyl alcohol to be 75o C. He looks in a reference book and finds that the actual boiling point of ethyl alcohol is 80oC.

Answer: _______________

5) The density of water at 4oC is known to be 1.00 g/mL. Kayla experimentally found the density of water to be 1.075 g/mL.

Answer: _______________