Conversion Factors and Calculations Lab 2

Conversion Factors and Calculations Lab 2

Conversion Factors and Calculations Lab 2 focuses on essential mathematical principles for converting units and calculating significant figures. It includes practical applications for students in science and engineering, emphasizing the importance of precision in measurements. The lab covers topics such as rounding rules, significant figures in multiplication and division, and conversion factors for length, volume, and mass. Ideal for high school and college students, this lab provides hands-on experience with calculations relevant to laboratory settings. Detailed examples and exercises enhance understanding of measurement accuracy and unit conversions.

Key Points

  • Explains rounding rules and significant figures in calculations.
  • Covers conversion factors for length, volume, and mass.
  • Includes practical exercises for calculating area and volume.
  • Demonstrates the importance of precision in scientific measurements.
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ConversionFactors in Calculations
Pre-lab Study Questions
1. What are the rules for rounding off numbers?
If the first number to be dropped is less than 5, drop it and all following numbers. If the first
number to be dropped is 5 or greater, drop the numbers and increase the last retained digit by
one.
2. How do you determine the number of significant figures in an answer obtained by multiplying or
dividing?
Answers for multiplication/division keep the same number of significant figures as the
measured number with the fewest significant figures.
3. How is the number of digits determined when an answer is obtained by adding or subtracting?
For addition/subtraction, an answer has the same number of decimal places as the measured
number with the fewest decimal places.
4. Is a body temperature of 39.4°C a normal temperature or does it indicate a fever?
The temperature 39.4 indicates a fever. Normal body temperature is 39.0°C. Converting
39.4°C to Fahrenheit gives
1.8 (39.4°C ) + 32 = 102.9°C
5. What is
an equality and how is it used to write a conversion factor?
An equality is the same measurement expressed in two different units. A conversion factor is
written by placing one of the units in the numerator and the other in the denominator. The
two are reversed for a second factor for the equality.
A. Rounding Off
A.1 Rounding A student rounded off the following calculator display to three significant figures.
Indicate if the rounded number is correct. If incorrect, round off the display value properly.
Calculator Student’s Correct (yes/no) Corrected (if needed)
Display Rounded Value
24.4704 24.5 Yes
143.63212 144 Yes
532, 800 530 No 533, 000
0.00858345 0.009 No 0.00858
8 8.00 Yes
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Report Sheet - Lab 2
A.2 Area
Your measurements Another student’s measurements
Length = 13.29 cm 13.25 cm
Width = 4.32 cm 4.35 cm (3 sig figs)
Area = 57.4 cm
2
57.6 cm
2
(Show calculations)
13.29 cm X 4.32 cm = 57.4 cm
2
13.25 cm X 4.35 cm = 57.6 cm
2
(3 sig figs)
Why could two students obtain difference values for the calculated areas of the same rectangle?
The estimated digit in each measurement will give some variation in the last digit of the
calculated area.
A.3 Volume of A Solid by Direct Measurement
Shape of solid rectangular solid
Formula for volume of solid L X W X H = V
height 2.85 cm length 4.82 cm
width 2.85 cm diameter (if cylinder) _____________
Volume of the solid 39.2 cm
3
(Show calculations of volume including the units)
4.82 cm X 2.85 cm X 2.85 cm = 39.2 cm
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(3 sig figs)
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Report Sheet - Lab 2
B. Significant Figures In Calculations
B.1 Perform the following multiplication and division calculations. Give a final answer with the
correct number of significant figures:
4.5 ✕ 0.28 1.3
0.1184 ✕ 8.00 ✕ 0.0345 0.0300
(42.4)(15.6) 5.23
1.265
(35.56)(1.45) 19
(4.8)(0.56)
B.2 Perform the following addition and subtraction calculations. Give a final answer with the correct
number of significant figures.
13.45 mL + 0.4552 mL 13.91 mL (2 decimal places)
145.5 m + 86.58 m + 1045 m 1277 m
1315 + 200 + 1100 2600 (last sig fig in hundreds place)
245.625 g - 80.2 g 165.4 g
4.62 cm - 0.885 cm _ 4.53
Questions and Problems
Q.1 What is the total mass in grams of objects that have masses of 0.2000 kg, 80.0 g, and 524
mg?
0.2000 kg X 1000 g/1 kg = 200.0 g
524 X 1 g/1000 mg = 0.524 g
Add 200.0 g + 80.0 g + 0.524 g = 280.5 g (one decimal place)
Q.2 A beaker has a mass of 225.08 g. When a liquid is added to the beaker, the combined mass is
238.254 g. What is the mass in grams of the liquid?
238.254 g – 225.08 g = 13.17 g (two decimal places)
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FAQs of Conversion Factors and Calculations Lab 2

What are the rules for rounding off numbers in calculations?
Rounding off numbers is guided by specific rules: if the first digit to be dropped is less than 5, it is discarded, and all following digits are also dropped. If the first digit to be dropped is 5 or greater, the last retained digit is increased by one. This method ensures that the rounded number maintains the appropriate level of precision based on the context of the calculation.
How do you determine significant figures in multiplication and division?
In multiplication and division, the result should have the same number of significant figures as the measurement with the fewest significant figures. This rule is crucial for maintaining accuracy in scientific calculations, as it reflects the precision of the least precise measurement involved in the calculation.
What is the significance of conversion factors in scientific calculations?
Conversion factors are essential in scientific calculations as they allow for the conversion of measurements from one unit to another. An equality expresses the same measurement in different units, and a conversion factor is derived from this equality. For example, knowing that 1 meter equals 1000 millimeters enables accurate conversions between metric units, which is vital in laboratory settings.
How is the area of a rectangle calculated using measurements?
To calculate the area of a rectangle, multiply the length by the width. For example, if the length is 13.29 cm and the width is 4.32 cm, the area is calculated as 13.29 cm multiplied by 4.32 cm, resulting in an area of 57.4 cm². This calculation emphasizes the importance of using precise measurements to ensure accurate results.
What are the conversion factors for common metric units?
Common metric conversion factors include 1 meter equals 1000 millimeters and 1 centimeter equals 10 millimeters. These factors are crucial for converting measurements in scientific experiments, ensuring that calculations are consistent and accurate across different unit systems. Understanding these conversions is fundamental for students in science and engineering disciplines.

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