1 What is energy? Energy makes objects move. makes things stop. is needed to “do work”.

2 What is Work ? Work is done when you climb. you lift a bag of groceries. you ride a bicycle. you breathe. your heart pumps blood. water goes over a dam.

3 What is potential Energy? Potential energy: energy stored for use at a later time. Examples are water behind a dam. a compressed spring. chemical bonds in gasoline, coal, or food.

4 What is kinetic energy? Kinetic energy: energy of matter in motion. Examples are swimming. water flowing over a dam. working out. burning gasoline.

5 What is a calorimeter? Heat is measured in joules or calories 1 kilocalorie (kcal) = 1000 calories (cal) A calorimeter measure heat transfer. can be made with coffee cup and thermometer. Indicates heat lost by sample Indicates heat gained by water.

6 Caloric Food Values On food labels, energy shown as nutritional Calorie, written with a capital C. caloric or energy values for foods indicate number of kcal(Cal) provided by 1 g of each type of food. Carbohydrate: 4 kcal 1 g Fat (lipid): 9 kcal 1 g Protein: 4 kcal 1 g

7 Energy Values for Some Foods amount of energy needed each day depends on age, sex, and physical activity

8 A cup of whole milk contains 12 g of carbohydrate, 9.0 g of fat, and 5.0 g of protein. How many kcal (Cal) does a cup of milk contain? 12 g carbohydrates x 4 kcal/g= 50 kcal (1 SF) 9.0 g fat x 9 kcal/g = 80 kcal (1 SF) 5.0 g protein x 4 kcal/g = 20 kcal (1 SF) 150 kcal Problem:

9 Temperature measure of how hot or cold an object compared to another object. Indicates heat flows from object with higher temperature to object with lower temperature. is measured using a thermometer.

10 Different Temperature Scales Temperature Scales are Fahrenheit, Celsius, and Kelvin. have reference points for boiling and freezing points of water.

11 Fahrenheit scale, there are 180°F between the freezing and boiling points and on Celsius scale, there are 100°C. 180°F = 9°F =1.8°F 100°C 5°C 1°C Fahrenheit temperature, adding 32 adjusts zero point of water from 0°C to 32°F. T F = 9/5 T C + 32  or T F = 1.8 T C + 32  Fahrenheit Formula

12 T C is obtained by rearranging equation for T F. T F = 1.8T C + 32 Subtract 32 from both sides. T F - 32 = 1.8T C ( ) T F - 32 = 1.8T C Divide by 1.8 =°F - 32 = 1.8 T C T F - 32 = T C 1.8 Celsius Formula

13 Solving A Temperature Problem A person with hypothermia has a body temperature of 34.8°C. What is that temperature in °F? T F = 1.8 T C + 32  T F = 1.8 (34.8°C) + 32° exact tenth's exact = ° = 94.6°F tenth’s

14 The normal temperature of a chickadee is 105.8°F. What is that temperature on the Celsius scale? T C = (T F - 32°) 1.8 =( °) 1.8 =73.8°F = 41.0°C 1.8° Problem:

15 A pepperoni pizza is baked at 455°F. What temperature is needed on the Celsius scale? T F - 32° = T C 1.8 ( °) = 235°C 1.8 Problem:

16 On a cold winter day, the temperature is –15°C. What is that temperature in °F? T F = 1.8 T C + 32  T F = 1.8(–15°C) + 32° = – ° = 5°F Note: Be sure to use the change sign key on your calculator to enter the minus – sign. 1.8 x 15 +/ – = –27 Problem:

17 Kelvin temperature scale has 100 units between freezing and boiling points of water. 100 K = 100°Cor 1 K = 1°C is obtained by adding 273 to Celsius temperature. T K = T C Contains lowest possible temperature, absolute zero (0 K). 0 K = –273°C Kelvin Temperature Scale

18 What is normal body temperature of 37°C in kelvins? T K = T C = 37°C = 310. K Problem:

19 States of Matter : Solids Solids have a definite shape. a definite volume. particles that are close together in a fixed arrangement. particles that move very slowly.

20 States of Matter: Liquids Liquids have an indefinite shape, but a definite volume. the same shape as their container. particles that are close together, but mobile. particles that move slowly.

21 States of Matter: Gases Gases have an indefinite shape. an indefinite volume. the same shape and volume as their container. particles that are far apart. particles that move very fast.

22 Summary of the states of matter Solid Liquid Gas

23 Changes of state: Melting and Freezing A substance is melting while it changes from a solid to a liquid. is freezing while it changes from a liquid to a solid. such as water has a freezing (melting) point of 0°C.

24 Changes of state: Sublimation Sublimation occurs when particles change directly from solid to a gas. is typical of dry ice, which sublimes at -78  C. takes place in frost-free refrigerators. is used to prepare freeze- dried foods for long-term storage.

25 Changes of state: Evaporation and Condensation Water evaporates when molecules on the surface gain sufficient energy to form a gas. condenses when gas molecules lose energy and form a liquid.

26 Changes of state: Boiling At boiling, all the water molecules acquire enough energy to form a gas. bubbles appear throughout the liquid.

27 Heating Curve A heating curve Illustrates changes of state as solid is heated. uses sloped lines to show an increase in temperature. uses plateaus (flat lines) to indicate a change of state.

28 Cooling Curve A cooling curve illustrates the changes of state as a gas is cooled. uses sloped lines to indicate a decrease in temperature. uses plateaus (flat lines) to indicate a change of state.