# Change, Constancy & Measurement

## Aluminum & Air Battery

In this Activity, students construct a simple battery from aluminum foil, saltwater, and activated charcoal. The battery can power a small motor or light. This Activity demonstrates oxidation and reduction reactions, which are integral parts of battery chemistry.

## Calories - Who's Counting?

In this Activity, students determine how many calories are released per gram when marshmallows and cashews burn and then compare the quantity of energy available from carbohydrates versus fats. Students burn the food items beneath a metal soft drink can containing water and measure the resulting change in temperature of the water.

## Cool! Rates of Heating and Cooling

In this Activity, students measure the rate of warming for a chilled thermometer bulb held in room temperature air, for a chilled bulb held between two fingers, and for a few milliliters of ice-cold water. Students discover that the warming process is not linear. This Activity emphasizes the importance of measuring temperature change and its relevance to other experiments.

## A Magnetic Meal

In this Activity, students make slurries of breakfast cereal and water and use a magnetic wand to collect elemental iron filings that are present in some cereals. They determine the mass of iron collected and then calculate the "recommended daily allowance" (RDA) in each cereal. An extension uses qualitative tests to confirm that the material collected is actually iron.

## How Does Your Laundry Glow?

In this Activity, students examine the effect of pH on the intensity and color of the emission of fluorescent dyes in liquid laundry detergent. They perform two titrations using vinegar to estimate the pH at which the fluorescence properties change. In the second titration, sodium bicarbonate is added to buffer the detergent solution.

## Flame Tests: Which Ion Causes the Color?

In this Activity, students perform simple flame tests using eleven commercially available compounds, cotton swabs, and a Bunsen burner. They then determine whether the cations or anions in each compound are responsible for the flame test colors. This Activity introduces students to flame tests in an inquiry-based manner.

## Fluorescent Fun: Using a Homemade Fluorometer

In this Activity, students investigate the fluorescence of highlighter marker ink and the principles employed in studying fluorescent molecules using a homemade fluorometer and different colored filters.

## A Cool Drink!: An Introduction to Concentrations

In this Activity, students investigate concentration levels by using serial dilution to prepare several solutions of presweetened powdered drink mix. Students taste the solutions to determine at which concentration they first discern the sweetness. A connection is also made to the concentration of pollutants in air.

## Hold the Heat: Global Warming and Calorimetry

In this Activity, students perform quantitative calorimetric measurements on samples of ice/water heated by incandescent light bulbs and/or convection with room-temperature surroundings. They measure and graph temperature as a function of time.

## Colors in Liquid Crystals

In this Activity, students investigate the relationship between temperature and composition and the reflected and transmitted colors of a common nanoscale material, the cholesteric liquid crystal.