U3 S1 L1 Temperature and Heat Textbook Readings MHR pages : Temperature Change and Heat Textbook Practice Items MHR page 638: items 1, 2, 3 and 8c page 657: items 1, 5, 6 and 7 page 659: item 22 page 706: items 9 and 10

Upon completion of this lesson, you should be able to: define thermochemistry distinguish between system and surroundings, and state the relationship of each to a universe define exothermic and endothermic with respect to heat exchange between a system and its surroundings define open, closed, and isolated (insulated) systems define temperature as a measure of the average kinetic energy of the particles of a system describe heat as a transfer of kinetic energy from a system of higher temperature (high average kinetic energy) to system of lower temperature (low average kinetic energy) when each is in thermal contact with the other identify and describe the changes to particle movement in systems in which the energy change is accompanied by a change in temperature of the system

The branch of science that deals with energy changes is called thermodynamics. –All physical, chemical and nuclear changes involve a change in energy Physical Chemical Nuclear Examples: The reaction between propane and oxygen produces carbon dioxide, water vapour and a lot of heat. An icicle melts in a person's hand. Heat is used to decompose limestone into carbon dioxide and calcium oxide. When sodium hydroxide is dissolved in water, there is a rapid increase in the temperature of water.

Systems and Their Surroundings a system is a substance or a group of substances undergoing a thermal, physical, chemical, or nuclear change. The surroundings is anything that is in thermal contact with the system. Together, system and its surroundings make up a universe. The connection between a system and its surroundings is heat flow.

~~~~Heat Flows~~~~ Heat flows from the surroundings to the system during endothermic changes –Energy is absorbed by the system Heat flows from the system to the surroundings in exothermic changes. –Energy is released by the system

3 types of systems 1.Closed open to the flow of energy, but closed to the flow of matter 2.Open –A system that is open to both the flow of energy and matter 3.Isolated –A system that is closed to both the flow of energy and matter

1.Closed System open to the flow of energy, but closed to the flow of matter For example, a gel filled freezer pack is a closed system. –Heat can flow out of the pack when it is put into the freezer, or into the pack when it is placed in a portable cooler. –The gel however, stays inside the plastic packaging. (ie: the amount (mass) of gel does not change) –For a closed system the system may be immersed in the surrounding but the system does not become part of the surroundings. Ie: Al placed in calorimeter water –a sealed bottle of soda cooling in a refrigerator –a reaction taking place in an aqueous medium e.g. acid-base neutralization reaction –nitrogen dioxide reacting to produce dinitrogen tetraoxide in a closed reaction vessel.

2. Open –A system that is open to the flow of energy and matter An open glass of cold water on the counter. The water can absorb energy from the outside air and it can lose mass by evapouration of the water. another example, –a “cold pak” that contains a inner pouch of NH 4 NO 3(s).inside a larger sealed pouch of water. –When the pouch of NH 4 NO 3(s) is broken it dissolves in the water. The process of dissolving absorbs energy from the water and the water cools. »System – dissolving NH 4 NO 3(s). »Surroundings – water in the pouch. –This is an open system in the sense that energy flows from the sys to the surroundings and the system combines and becomes part of the surroundings –For an open system the system mixes (or can react with) the surroundings. That is the system (object or process) becomes part of the surroundings and thus adds to the mass of the surroundings. Ie: heat of solution formation for NaOH

3. Isolated –A system that is closed to the flow of energy and matter

Temp Vs: Heat Particles of matter exhibit three types of motion: vibrational, rotational, translational. 1.Vibration is moving back and forth in a fixed position. An analogy for it a person shivering. It is the motion associated with particles in the solid state. 2.Rotation is spinning. An analogy for a particle in rotational motion is a figure skater in a spin. Particles in the liquid and gas states have rotational energy. 3.Translation is moving from point A to point B etc. An analogy is a pin-pong ball's motion during a table tennis match. Molecules in the liquid and gas states have translational energy. The kinetic energy of a particle is a function of its motion. –Ie: KE is energy of motion.

Temperature is an indirect measure of kinetic energy. –When we measure temperature, we are getting an indication of the average kinetic energy (speed) of all the particles in a sample of matter. Depends on speed of molecules. Heat is energy which is transferred as a result of a temperature difference. – Heat flows from a warmer object to a cooler object. –At the molecular level, "warm" molecules lose kinetic energy to "cooler" molecules through collisions. –The thermal energy flows from warm to cool molecules until the average kinetic energies of the two groups of molecules become equal - a condition known as thermal equilibrium. Depends on both mass and speed.

1.Distinguish between chemical, physical and nuclear changes. Give an example of how energy is involved in each type of change. 2.For each description, identify the system and the surroundings. Classify each system as open or closed. Justify your choices. 1.Moisture condenses on a window. 2.A marshmallow burns in air. 3.Crystals of potassium iodide are added to a beaker containing an aqueous solution of lead(II) nitrate. A yellow precipitate forms and the temperature of the water increases slightly. 4.An ice cube melts in an open hand

4. Two bundles of copper wire have different mass, but the same temperature. What can you say about the average kinetic energy of the copper atoms in each bundle?