The Physics Of Thermal Energy

Calorimetry is the science of measuring the change in heat absorbed or released during a chemical reaction. The change in heat can tell us if the reaction is either exothermic - it released or heat into surroundings, or endothermic - it absorbed heat from surroundings. The device used to measure calorimetry is a calorimeter. A calorimeter can range from very expensive lab ones to coffee styrofoam cups but they are all tightly sealed in order to prevent heat from escaping.

Heat: The amount of energy associated with the movement of atoms and molecules in matter.

In part I, the ΔH of each individual reaction was obtained by performing each reaction inside a calorimeter. Temperature probes were inserted in the calorimeter and ΔT was measured. By using the equation q = Msol’n x Cp x ΔT + Ccal x ΔT, the heat absorbed by the surroundings, q, was obtained for each reaction. The negatives of these values, or heat released by the

Exothermic reactions transfer energy to the surroundings. The energy is usually transferred as heat energy, causing the reaction mixture and its surroundings to become hotter. The temperature increase can be detected using a thermometer. Some examples of exothermic reactions are:

Chemical reactions that release energy are called exothermic reactions, these reactions are observed by an increase in temperature of the reaction mixture.

In 1 gram of ice, the addition of 20 calories of heat raises the temperature of the ice by 40 degrees Celsius, from -40 degrees Celsius to 0 degree Celsius. The temperature remains at 0 degree Celsius (32 degrees Fahrenheit) even though more heat is being added. The temperature of water does not change until 80 more calories of heat energy have been added. The latent heat of melting is the energy needed to break the intermolecular bonds that hold water molecules rigidly in place in ice crystals. The temperature remains unchanged until all of the bonds are broken and the mixture of ice and water has changed completely to 1 gram of water.

Thermal energy is the total energy of the moving particles in a solid. Thermal energy from a hot stove is transferred to a metal pot and causes the water particles to move faster increasing the temperature of the water Changes of state: Changes from one state to a gas, liquid or solid. Example, you leave ice cream out in a hot summer day and it melts. Gravitational energy:

Purpose: To utilize a calorimeter correctly to find the enthalpy changes in two different reactions. The purpose was also to use concepts of specific heat to observe the relationship between temperature observations and heat transfer. Then, use the equations to see the relationship between change in energy and the amount of substance involved. Use Hess’ law to determine the change in energy.

Thermal energy is the energy a substance or system has related to its temperature. This means the energy of moving or vibrating molecules. Atoms and molecules are always in motion. Generally the motion of thermal energy cannot be seen, but instead the effects it has on the substance can be seen or felt. Thermal energy can have several different uses. It can be used to heat homes, cook food, and generate electricity.

Introduction: The theory behind this experiment is the heat of a reaction (∆E) plus the work (W) done by a reaction is equal to

Heat is a form of energy that is transferred between two substances at different temperatures. The flow of the energy is from the object of higher temperature to the object of lower temperature. The heat is measured in units of energy, usually calories or joules. Temperature on the other hand, is how cold or hot an object is. The temperature is the average kinetic energy per molecule of a substance. This is measured in degrees on the Celsius or Fahrenheit or in Kelvins.

Background: Energy changes occur in all chemical reactions; energy is either absorbed or released. If energy is released in the form of heat, the reaction is called exothermic.

Purpose: This lab taught procedures for determining heat of capacity of a calorimeter and measuring enthalpy of change for three reactions. It also enforced methods of analyzing data obtained through experimentation and calculating enthalpy. These procedures are used in the branch of thermodynamics known as thermochemistry which is the study of energy changes that accompany chemical reactions. Concepts from this lab can be used to determine the potential energy of a chemical reaction. Much of the energy people depend on comes from chemical reactions. For example, energy can be obtained by burning fuel, metabolizing of food or discharging a batter.

Introduction: Every chemical change is accompanied by a change in energy usually in the form of heat. If heat is evolved, the reaction is exothermic, and if heat is absorbed, the reaction is endothermic. The energy change of a reaction that occurs at constant pressure is called the heat of reaction or the enthalpy of reaction (ΔHr). This quantity of heat is measured experimentally by allowing the reaction to occur in a calorimeter. In this experiment you will determine the heat of neutralization when an acid and a base react to form 1 mole of water. In a perfect calorimeter, heat is exchanged only between the reaction and the calorimeters water. Technically, some heat may may be absorbed the calorimeter. All calorimeters exchange some heat with its environment. This amount of heat is called the calorimeters heat capacity (the amount of of heat required to raise its temperature 1∘Celsius). We are going to “pretend” that our calorimeter is the perfect calorimeter.

ACTIVITY 5. POWER OF A STUDENT (Teacher’s Notes) PROCESS SKILLS: Measure, Observe, Compare, Test, Explain OBJECTIVE: The objective of this activity is to motivate the concept of power, or rate at which energy is transformed, and to apply it to the rate at which students do work to increase their gravitational potential energy in climbing a flight of stairs. IDEA: Students are asked to measure their gain in gravitational potential energy as they climb a flight of stairs, then to calculate the rate at which this potential energy is gained. This is followed by asking students to calculate their body’s energy needs for a day, both to perform various physical activities (including the climbing of stairs) and to maintain internal body functions.