# Density

## Introduction:

Students will determine the density of 2 unknown liquids by collecting mass and volume data. Each group of students will be given a different volume of the liquids to measure, they will combine their data to create a graph. Using the graph students will determine the density of the two liquids by calculating the slope of the two lines. Students will also use a graphing calculator to determine the slope of the two lines. This activity is a wonderful way to integrate Chemistry and Algebra 2 because the measuring of density is simple enough to do in an Algebra 2 class and using a hand drawn graph and a calculator to determine the slope are skills students need to master for Algebra 2. It also shows students a use for slope in a data collection scenario.

## Learning Outcomes:

• Students will accurately measure the volume and mass of a liquid.
• Students will graph the class data by hand and determine the slope of the lines.
• Students will graph the class data using a graphing calculator and determine the slope of the lines.
• Students will identify the slope of the lines as the density of the liquids.
• Students will identify the liquids from their respective densities.

## Curriculum Alignment:

Chemistry SCOS:

• 1.01: Design, conduct and analyze investigations to answer questions related to chemistry.
• 1.02 Analyze reports of scientific investigations from an informed scientifically-literate viewpoint including considerations of:
• 1.03 Analyze experimental designs with regard to safety and use safe procedures in laboratory investigations:
• 2.04 Identify substances using their physical properties: Density

Algebra 2 SCOS:

• 2.04 Create and use best-fit mathematical models of linear, exponential, and quadratic functions to solve problems involving sets of data.

• 20 min

## Materials Needed:

• 2 liquids
• Balances
• 10mL and 25mL graduated cylinders
• Graphing Calculators
• Graph Paper
• Reference Tables with densities of liquids.

## Technology Resources

Graphing Calculators

## Pre-Activities:

The teacher should make sure that students can calculate density. They must also be able to calculate the slope of a line and use a graphing calculator to input data and graph it. Teach/Review how to calculate percent error.

## Activities:

• The teacher should begin with how to calculate the density of a liquid.
• The teacher should also explain how to accurately measure mass and volume of a liquid.
• The teacher should review how to determine the slope of a line from a graph and on the calculator.
• The students will collect and accurately record mass and volume data for 2 liquids.
• The students should write their data on the board or overhead for all to copy.
• Once all data is collected the students are to complete the post lab activities.
• The teacher should use the class data to determine the slope of the 2 lines of data provided by the students for checking their answers later.

## Assessment:

• Post lab questions are provided.

## Critical Vocabulary:

• Density
• Slope
• Line of best fit
• Mass
• Volume
• Linear regression
• List
• Stat plot
• Percent error.

## Websites & Resources:

The Texas Instruments website is a great resource for calculators and for instructions on how to use the calculator if you or your students are not familiar. ( www.ti.com)