Warm up: In your composition book. In your own words, describe Heat. In your own words, define temperature.

Temperature and Heat We are starting a new chapter Title today’s notes: Temperature and Heat

Thermal Energy: All matter is made of particles These particles are always bouncing around. These particles have kinetic energy and potential energy. Thermal energy is the total amount of potential and kinetic energy contained in the particles that make up a substance.

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Temperature Temperature is a measure of the average kinetic energy of all the particles in an object. tells how hot or cold something is Higher KE=Higher temperature Lower KE=Lower temp

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Boiling Water in a Paper Cup Heat Heat is the movement of thermal energy from warm objects to cooler objects. Thermal energy always flows to the objet with lower temp until thermal Equilibrium is reached. Thermal Equilibrium occurs when all objects have reached the same temperature. Boiling Water in a Paper Cup

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Specific Heat Different substances heat up more easily than others. Specific heat: The amount of thermal energy needed to raise the temperature of 1kilogram of a material 1°C Different substances heat up more easily than others. Look at pg. 325 Table 1 What object has the highest specific heat? What object has the lowest specific heat? Which object is the easiest to warm up?

Table of Specific Heat Values Substance Specific Heat (cal/g0C) (J/kg0C) Air 0.25 1,046 Aluminum 0.22 899 Copper 0.09 387 Glass 0.20 837 Ice (-200C to 00C) 0.50 2,090 Iron 0.11 448 Mercury 0.03 138 Ocean Water 0.93 3,894 Water 1.00 4,187 Wood 0.42 1760

Look at formula on page 326 Write down formula in your notes

Calculating changes in thermal energy Change in thermal energy=(Mass)(Temperature change)(Specfic Heat) Formula: Q=(m)(ΔT)(C) What does Q stand for? What does ΔT stand for? What does C stand for?

Copy down this Practice problem The air in a room has a mass of 50 kg and a specific heat of 1,000J/(Kg°C). What is the change in thermal energy of the room when it warms from 20°C to 30°C?

Calculating thermal energy changes Thermal energy equation. (mass)(Tempfinal-Tempinitial)(specific heat)=Change in thermal energy Q=m(Tf-Ti)C Assignement. Complete problems 1-10 on page 142,143

Warm up 11/16/15 An equal mass of water and rubbing alcohol are heated at the same rate for 10minutes. At the end 10 minutes the alcohol has a higher temperature. Which one has the higher specific heat?

Specific Heat Capacity the amount of energy needed to change the temperature of 1 kg of a substance by 10C how easily substances change temperatures Water has a very high specific heat capacity the higher the speciific heat  the more energy and the longer it takes for something to heat up and cool down. to heat up or cool down can be used to help calculate heat lost or gained by a substance formula: mc∆T

Using Specific heat to calculate change in energy. Water has specific heat of 4200J/(kg°C) Using this value we can calculate how much energy was transferred by each type of material in our lab. -Change in thermal energy=(mass)(Temperature change)(specific heat) IF we calculate how much thermal energy was added to the water when dropped our object into the water, we can figure out how much energy the object had.

Example Q=Change in thermal energy Mass=Mass of water in foam cup Temperature change= Temp after object is dropped in-Temp before object is dropped in specific heat=4200 Q=(m)(Tempbefore-Tempafter)(C)

Example You had 100mL water which =0.1kg If temp went from 17-21, tempfinal-timepinitial=21-17=4 Specific heat of water of 4200J/Kgc Q=(0.1kg)(4)(4200)=1680J was added to the water by the nut.

Thermal Energy vs. Temperature vs. Heat the total energy of the particles in a substance a measure the average kinetic energy of all the particles in an object the transfer of energy between objects that are at different temperatures expressed in joules expressed in degrees Fahrenheit, Celsius, or Kelvin expressed in joules or calories varies with the mass and temperature of a substance does not vary with the mass of a substance varies with the mass, specific heat capacity, and temperature change of a substance

Conduction transfer of thermal energy through a substance, or from one substance to another by direct contact of particles takes place in solids, liquids, and gases, but takes place best in solids because the particles of a solid are in direct contact with each other Unfortunately for someone, after being touched, the heat will transfer from the iron to the hand. What are some other real-life examples where heat is transferred by conduction?

Conductors and Insulators substances that conduct thermal energy well particles are close together different metals are common conductors Insulators substances that do not conduct thermal energy well  they delay heat transfer particles are far apart different plastics are common insulators What are some common conductors and insulators? Melting Blocks

Convection transfer of thermal energy through fluids (liquids or gases) by means of up and down movements called convection currents the circular motion of liquids or gases due to density differences that result from temperature differences As the air gets heated by the flame, the particles move faster and spread out. This increases the volume of the air inside the balloon, which lowers the density. This decrease in density causes the balloon to rise. Sea and land breezes result from uneven heating of the Earth’s surface and the resulting convection currents. Explain how this happens.

Radiation transfer of thermal (radiant) energy as electromagnetic waves, such as visible light or infrared waves energy can be transferred through matter or empty space darker objects absorb more radiant energy than lighter objects Notice how the visible light from the sun travels through space and heats the Earth.

Calculating Heat – Sample Problem How many joules are needed to raise the temperature of 100 kilograms of copper from 10 C to 100 C? The specific heat of copper is 387 J/kg·C. Take the difference between 100C and 1000C Q = mc∆T heat mass specific heat change in temperature Heat = (100 kg) 387 J kg·C (90 C) Heat = 3,483,000 J