Read page D-64

Activity 65 Title: Chemical Batteries Problem: What combination of metal makes the best battery to power a small motor? Hypothesis: If _____________, then ____________________________.

Does anyone know what goes on inside a battery? What do a battery and a peanut have in common when we consider them as a source of energy? Does anyone know what goes on inside a battery? Batteries are full of chemicals A battery is an energy transformer A chemical reaction releases electrical energy Batteries use two different materials, usually two metals that serve as positive and negative terminals

Electrolytes An electrolyte is a material capable of conducting electricity that allows the current to flow as it is released from the reaction. The electrolyte material in an alkaline battery, for example, is potassium hydroxide or manganese dioxide paste. The nature and the amount of materials inside the battery determine how much potential chemical energy is available.

Background Information: Batteries A battery is a device that transforms chemical energy into electrical energy through a chemical reaction. When a battery is put in a flashlight and the light is turned on, a path for electron flow has been connected. Different metals have different chemical properties which makes some metals react more readily because the electrons in the more reactive metals are more loosely held and are readily lost to other materials

Electrochemical Cell In a copper-and-magnesium battery the magnesium gives up electrons to form positive magnesium ions, and positive copper ions gain these electrons to form a coating of copper on the copper bar. The metals are called electrodes. Two different metals are placed in a salt solution (the electrolyte) and connected by a salt bridge and wire. Electrons (current) flow from the more reactive to the less reactive metal. This current passes through a circuit. If the light bulb is in contact, and the current is sufficiently strong, the bulb will glow

Reactivity of Metals Hint: Free electrons are produced during the reaction in a battery, electricity is the flow of electrons. Reactivity of Metals Metal With Copper Chloride Magnesium Reacts rapidly Aluminum Zinc Reacts Slowly Iron Copper No reaction

Materials Each Bin Should Have 1 30-mL dropper bottle of 3% hydrogen peroxide solution 1 small piece of sandpaper Roll of Masking Tape And should have 2 sets of 1 SEPUP wet cell chamber 1 1.25 cm x 37.5 cmx32.5 mm strip of each of the following metals: copper iron magnesium zinc 5 packages of table salt 1 plastic spoon 1 50-mL graduated cylinder 2 wire leads-one red and one black 1 27O-mL (9-oz.) plastic cup 1 electric motor

Procedure Part A Make a flag with the masking tape You will use the motor to measure how much energy your battery produces by observing how quickly the shaft turns. Connect one end of the red jumper cable to the pin on the motor marked with a red dot. Connect the black cable to the other pin. One person should hold the motor during each battery test and count how many times the shaft turns in 10 seconds. All group members must make observations

Important Hints One person is to hold the motor. The masking tape “flag” should be small and not touch the motor. After the connections are made, you may gently push the flag to help the motor begin turning. Before lowering the metal strips into the wet cell solutions, attach each lead to the motor and to one end of a metal strip. Some of the reactions last only a few seconds, so don’t lower the metal strips into the solutions until you are prepared to make your observations. At the beginning of each test, use a piece of sandpaper to clean the surface of the metals.

Procedure Part B Stop after part A Write Activity 65 Preliminary Questions With your group, design an investigation to test the other combination of metals. What is the purpose of your investigation? What will you observe or test? What materials will you need to conduct your investigation. How will you record your observations? How will you use the results to make a conclusion?

Procedure Part B: Pour the electrolyte into the SEPUP wet cell Connect the wire leads to the motor and the metal strip combinations as described in table 1. Lower two strips of different metals into the outside slots of the SEPUP wet cell. There should be a small amount of metal sticking out of the cells. Give the flag a push if necessary and observe the motor spinning for 10 seconds. Record observations in a data table. Disconnect the wire leads. Remove the two metal pieces. Dry them, and then clean both sides with a piece of sandpaper. Repeat Steps 2-6 for all the metal combinations listed on table 1.

Follow-up Fill in the information for table 2 What do you conclude from your data? Do you have any ideas why some combinations worked better than others in providing energy for the motor?

Part C:

By analyzing the results of many experiment involving metals reacting with each other, scientists have produce a table of metal activities that help us predict what will happen in any pairing of two metals. Major Concepts: A battery transforms potential chemical energy into electrical energy. When the circuit is completed, electrical current is allowed to flow from the negative pole of a battery to the positive pole.