Chapter 16, Problem 26A

Does a fully charged flashlight battery weigh more than the same battery when dead? Defend your answer.

To determine

To identify: Whether fully charged flashlight battery weigh more than the same battery when dead or not.

Explanation of Solution

Introduction:

Electric battery is the device which is used to store the electrical energy and use as per the requirement. In battery, when load is connected chemical energy is converted into the electrical energy. There are main three parts of the battery, anode, cathode and electrolyte. Cathode is positive terminal pf the battery, whereas anode is source of electrons which is negative terminal of battery. There are various types of batteries available like primary, secondary, etc.

Battery basically works on the oxidation and reduction reaction. Due to that reaction’s electrons flow from one electrode to another through the external circuit. Redox reaction at different electrode produce electron concentration gradient. In order to maintain charge conservation in the circuit, electrolyte creates an ion that move through the electrical circuit. That electron gradient creates potential difference which is the source of electric voltage in circuit. Without applying the external voltage, the driving force for the electrochemical reaction is the reduction in Gibb’s free energy at constant pressure and temperature. So, the change in Gibb’s free energy is equal to the electrical energy. In the process of charging charges moved through the circuit and stored energy. So, due to storing of the charges leads to addition of some amount of mass equivalent to mass of the charges in the electrochemical charging process. When the battery is discharging, available stored charge flow out through the process and electrical energy is decaying. When charging starts chemical energy is again started converting into the electrical energy through the electrochemical reaction and storing the charges.

Conclusion:

Therefore, fully charged flashlight weigh more than the battery when dead. This increase in weight of the charged battery is because of storing of the charges.