In this lesson, students will learn how to use dimensional analysis for unit conversion problems.They will then practice the skill on several chemistry-based conversion problems.
By the end of this lesson, students should be able to
- use dimensional analysis for mass, length, volume, temperature, and density unit conversion problems
This lesson supports students’ understanding of
- unit conversion
- dimensional analysis
Teacher Preparation: 5 minutes
Lesson: 45 – 60 minutes
- Dimensional Analysis PowerPoint presentation
- Student Handout
- No specific safety precautions need to be noted.
- Show your students The Temperature Guys video from the Founders of Chemistry video series on the AACT website, before starting the unit conversion lesson. This will help to begin a discussion about why units are important.
- Use the supplied PowerPoint presentation to guide your student through a few examples of unit conversion problems using dimensional analysis.
- The lesson opener asks, “When does 0.5 – 60 = 11?”The answer – it all depends on units.A half (0.5) day is 12 hours. Subtract one hour (60 minutes) and you get 11 hours.
- Have 100 pennies, 10 dimes, 4 quarters, and 1 dollar bill ready for the second slide.Ask students what the four have in common (same amount of money) and how they differ (each has a different monetary value and you need different amounts of each to have a dollar)
- Have a meter stick that also has inch markings.Talk about the metric markings and how they are related.Then compare the inch markings to the centimeters markings.
- You may want to follow this lesson with the Unit Conversion Online Tutorial activity.
For the Student
Dimensional Analysis Practice Problems
- Convert 3.55 liters into milliliters.
- Convert 1.64 pounds to grams and milligrams.
- Convert 7.2 meters to centimeters and inches.
- Convert 16,450 milligrams to grams and pounds.
- Convert 12.0 feet into centimeters and meters.
- Convert 1.500 days into minutes and seconds.
- The highest temperature recorded in Washington D.C. was 106°F on July 20, 1930.Convert the temperature to °C and K.
- On the 4th of July, a sparkler burns at a temperature of 1644K.Convert the temperature to both °C and °F.
- I like my steak cooked medium rare – which means it will have an internal temperature of 135°F.Convert this temperature to °C and K.
- A student finds a rock on the way to school. In the laboratory he determines that the volume of the rock is 22.7 cm3, and the mass in 39.943 g. What is the density of the rock?
- Calculate the density of a material that has a mass of 52.457 g and a volume of 13.5 cm3.
- The density of zinc is approximately 7.13 g/mL.
- What is the volume, in cm3, of a 5.00 g piece of zinc?
- What is the mass of a 45.6 L block of zinc?
- A sample of iron has a volume of 25.0 cm3 has a mass of 174 grams.Calculate the density of iron.
- What would be the mass of 15.0 of cm3 iron?
- What would be the volume of 1000. grams of iron?