Thermochemistry Module 2 Energy, Heat, Temperature

Pop Quiz module 2 1. Temperature units are: 1. ºC, ºF, K 2. ∆T 3. ºF, K, ºQ 4. ºC, ºF, L 4.a 2.Energy can be destroyed 1. True 2. False 5.A hypothesis is always correct 1. true 2. false 3.If ice and water are mixed the temperature of the mixture will stay the same regardless of the amount of ice or water present. 1. True 2. False

Module 2 Thermochemistry Heat Energy that can be transferred due to the molecular movement Temperature Measurement of molecular movements units are ºC, ºF, K Move ment of molec ules

How are Heat and Temperature related? Heat (q) is the total amount of energy that transfers from one object to another. Heat is an extensive property and changes based on the amount of matter present. Temperature measures the intensity of the energy and heat measures the quantity of energy. The temperature of an object determines the direction of heat transfer. When two objects of different temperatures are in contact, heat moves from the object at the higher temperature to the object at the lower temperature until they are both at the same temperature.

Thermochemistry Study of energy transfer in the form of heat in a chemical reaction or phase change Energy Ability to do work Work Force applied to an object x distance the object travels parallel to that force Kinetic Energy Energy that is in motion Potential energy Energy that is stored Matter contains kinetic and potential energy Heat and temperature are used to describe the energy content of matter

Mass is measured in grams Mass measure of the amount of substance in an object weight measure of the gravitation pull of earth on an object Volume is measured in liters chemistry the study of matter volume measure of the amount of space occupied Distance is measured in meters precision indication of the scale on the measuring device that was used metric system system of standard units density a measure of the amount of mass per unit volume accuracy indication of how close a measurement is to the true value matter anything that has mass and takes up space

1cc= ml Correct answers: 1, one A significant figure is a non zero number Correct answer: True weight: 0 A significant figure is a zero at the end of a number (and to the right of the decimal point) Correct answer: True A significant figure is a zero to the left of the decimal. Correct answer: False The order of metric units from smallest to largest is: cm, mm, km, k mm, cm, m, km km, m, cm, mm 44.5 L = cm³ Correct answers: 44500, 44,500, ^4 Aluminum has a density of 2.70 g/cm³. What would the mass of a sample whose volume is 10.0 cm³ g g 27.0 g g

The number in scientific notation is: 1.57 x x x x How many feet are in 6.4 m? conversion factors: 1 yard = 3ft 1 mile = 5280 ft 1000g = 1kg 1 m = 100 cm 1 ft = 12 in 1 in = 2.54 cm 1 kg = 2.2 lbs 21 m 2.1 m 210 m.21 m Extra Credit Extra credit worth 10 extra points A box is measured to be 6.2 m x 4.7 m x 2.6 m. What is its volume in cubic centimeters? 7600 cm cm x x 10 3

Pop Quiz 5 – Module 2 1.Heat is measured by: 1. º C 2. º F 3. Joules 4. K 2. The specific heat of water is measured by calories or joules 1. True 2. False 3. The process that chemists use to measure heat is 1. Calories 2. Joules 3. Calorimetry 4. energy 4. A wood table has potential energy 1. true 2. false 5. Fire is an example of kinetic energy 1. true 2. false

Thermochemistry Study of energy transfer in the form of heat in a chemical reaction or phase change Energy Ability to do work Work Force applied to an object x distance the object travels parallel to that force Kinetic Energy Energy that is in motion Potential energy Energy that is stored Matter contains kinetic and potential energy Heat and temperature are used to describe the energy content of matter Heat is considered kinetic energy

Heat gained endothermic Heat lost exothermic

Key concepts in book:

Add a Slide Title - 4 Heat that is absorbed or released ∆ = (delta) change in

1. How much heat (q) is needed to change the temp of 50.0g of water 20.0ºc? q = 4184 j 2. If 200.0g of Aluminum with a starting temperature of 20.0ºc is given j of energy what would the final temperature of the aluminum be? 2.78Tf – 20.0 Ti = º c

3. A 45.0 g slug of steel at 150º c is placed into 100.0g of water at 20 º c 4. How will the final temp of the steel compare to the final temp of the water? Write the equation for calculating the energy (heat) for steel 45.0 g * 150ºc * j

The mass of our aluminum sample is 51.3 grams Next we need to heat our piece of brass by putting it in some hot water.

We will heat our sample of aluminum in a beaker of water on a hot plate. Let's adjust the temperature to 70.0°C. Next we need to put the hot aluminum into water and see how much the temperature is increased.

Putting our 51.3 gram sample of aluminum heated to 70.0°C into 100 grams of water at 20.0°C raised the temperature of the water to 24.8°C. Let's calculate the specific heat of our sample of aluminum.

It takes 1 calorie to change the temperature of 1 gram of water 1°C. In this experiment, putting our sample of hot aluminum into 100 grams of water raised the temperature from 20.0°C to 24.8°C. How many calories did this take? Right, it taks 480 calories to heat 100 grams of water 4.8°.

Warming 100 grams of water from 20.0°C to 24.8°C took 480 calories. How many calories were lost from your sample of aluminum when it cooled from 70°C to 24.8°C? Right, all the heat from the aluminum went to heat the water.

Summary of Temperature Changes Hot Aluminum70.0°C Cold Water20.0°C Final Temperature24.8°C We started with aluminum at 70.0° and water at 20.0°. The final temperature was 24.8°. What was the temperature change in the sample of aluminum? Right, the temperature change in the aluminum was 45.2°C

You found that it takes 480 calories to change the temperature of 51.3 grams of aluminum 45.2°C. what should we enter for the energy in this equation? 480 calories 51.3 g 20.0 ° 45.2 ° Right, the energy change was 480 calories.

You found that it takes 480 calories to change the temperature of 51.3 grams of aluminum 45.2 °C. What should we enter for the mass in this equation? 480 calories 51.3g 20.0 ° 45.2 ° Right, the mass of the aluminum was 51.3 grams.

You found that it takes 480 calories to change the temperature of 51.3 grams of aluminum 45.2°C. What should we enter for the temperature change in this equation? 480 calories 51.3g 20.0 ° 45.2 ° 45.2 ° Right, this gives a specific heat of 0.21 cal/gramºC.