1 / 22

Chapter 6 Energy and States of Matter - PowerPoint PPT Presentation

Chapter 6 Energy and States of Matter. Measuring Heat Energy Energy and Nutrition. Heat. Energy that flows from something warm to something cooler A hotter substance gives KE to a cooler one

Related searches for Chapter 6 Energy and States of Matter

I am the owner, or an agent authorized to act on behalf of the owner, of the copyrighted work described.

Chapter 6 Energy and States of Matter

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.

- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript

Chapter 6Energy and States of Matter

Measuring Heat Energy

Energy and Nutrition

LecturePLUS Timberlake 99

• Energy that flows from something warm to something cooler

• A hotter substance gives KE to a cooler one

• When heat is transferred (lost or gained), there is a change in the energy within the substance

LecturePLUS Timberlake 99

A. When you touch ice, heat is transferred

from

1) your hand to the ice

2) the ice to your hand

B. When you drink a hot cup of coffee, heat

is transferred from

1) your mouth to the coffee

2) the coffee to your mouth

LecturePLUS Timberlake 99

A. When you touch ice, heat is transferred

from

1) your hand to the ice

B. When you drink a hot cup of coffee, heat

is transferred from

2) the coffee to your mouth

LecturePLUS Timberlake 99

When you heat 200 g of water for 1 minute, the water temperature rises from 10°C to 18°C.

If you heat 400 g of water at 10°C in the same pan with the same amount of heat for 1 minute, what would you expect the final temperature to be?

1) 10 °C2) 14°C 3) 18°C

400 g

200 g

LecturePLUS Timberlake 99

2)14°C

Heating twice the mass of water using the same amount of heat will raise the temperature only half as much.

400 g

200 g

LecturePLUS Timberlake 99

Heat is measured in calories or joules

• 1 kcal = 1000 cal

• 1 calorie = 4.18J

• 1 kJ = 1000 J

LecturePLUS Timberlake 99

• Why do some foods stay hot longer than others?

• Why is the beach sand hot, but the water is cool on the same hot day?

LecturePLUS Timberlake 99

Different substances have different capacities for storing energy

It may take 20 minutes to heat water to 75°C. However, the same mass of aluminum might require 5 minutes and the same amount of copper may take only 2 minutes to reach the same temperature.

LecturePLUS Timberlake 99

Specific heat is the amount of heat needed to raise the temperature of 1 g of a substance by 1°C

cal/g°CJ/g°C

water 1.00 4.18

aluminum0.22 0.90

copper0.093 0.39

silver0.057 0.24

gold0.031 0.13

LecturePLUS Timberlake 99

A. A substance with a large specific heat

1) heats up quickly2) heats up slowly

B. When ocean water cools, the surrounding air

1) cools 2) warms3) stays the same

C. Sand in the desert is hot in the day, and cool

at night. Sand must have a

1) high specific heat 2) low specific heat

LecturePLUS Timberlake 99

A. A substance with a large specific heat

2) heats up slowly

B. When ocean water cools, the surrounding air

2) warms

C. Sand in the desert is hot in the day, and cool

at night. Sand must have a

2) low specific heat

LecturePLUS Timberlake 99

Requires

• Grams of substance

• Temperature change T

• Specific heat of the substance

LecturePLUS Timberlake 99

Calculating Heat

mass x temp. change x specific heat

grams x T x Sp. Ht.

LecturePLUS Timberlake 99

A hot-water bottle contains 750 g of water at 65°C. If the water cools to body temperature (37°C), how many calories of heat could be transferred to sore muscles?

heat = g x T x Sp. Ht. (H2O)

750 g x 28°C x 1.00 cal g°C

= 21 000

LecturePLUS Timberlake 99

How many kcal are needed to raise the temperature of 120 g of water from 15°C to 75°C?

1) 1.8 kcal

2) 7.2 kcal

3) 9.0 kcal

LecturePLUS Timberlake 99

How many kcal are needed to raise the temperature of 120 g of water from 15°C to 75°C?

2) 7.2 kcal

120 g x (75°C - 15°C) x 1.00 cal x 1 kcal

g°C 1000 cal

LecturePLUS Timberlake 99

1 Calorie (nutritional) = 1 kcal

1 Cal= 1000 cal

LecturePLUS Timberlake 99

Carbohydrate = 4 kcal/g

Fat = 9 kcal/g

Protein = 4 kcal/g

LecturePLUS Timberlake 99

FoodCarboFatProtein Energy(kcal

carrots,

1 cup 11 0 1 50

banana 26 0 1 110

egg 0 6 6 80

chicken

(no skin) 0 3 20 110

beef (3 oz) 0 5 22 130

LecturePLUS Timberlake 99

1.0 cup of whole milk contains 12 g of carbohydrate, 9.0 g of fat, and 9.0 g of protein. How many kcal (Cal) are obtained?

1) 48 kcal

2) 81 kcal

3) 165 kcal

LecturePLUS Timberlake 99

3) 165 kcal

12 g carbo x 4 kcal/g = 48 kcal

9.0 g fat x 9 kcal/g =81 kcal

9.0 g protein x 4 kcal/g=36 kcal

Total kcal= 165 kcal

LecturePLUS Timberlake 99