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Specific Heat Capacity

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Presentation on theme: "Specific Heat Capacity"— Presentation transcript:

1 Specific Heat Capacity

2 Temperature vs. Heat Temperature is the measurement of the avg. KE of the particles in matter. Heat energy that flows from a warmer object to a cooler object. Let’s review the difference between temperature and heat from yesterday, temperature is the measurement of the average Kinetic Energy of the particles in matter and heat is the energy that flows from a warmer object to a cooler object.

3 Heat flows from WARMER to COOLER!
Heat always flows from warmer to cooler!

4 Learning Check 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 So when you touch ice is the heat transferred from your hand to the ice or the ice to you hand, well since heat ALWAYS flows from warmer to cooler then it would be from your hand to the ice. What about when you drink a hot cup of coffee? Is the heat transferred from your mouth to the coffee or the coffee to your mouth. Again heat ALWAYS flows from hot to cold so it would be from the coffee to your mouth.

5 OR maybe that the ocean is cooler than the hot sand?
Have you ever noticed that on a hot summer day the pool is cooler than the hot cement? OR maybe that the ocean is cooler than the hot sand? Have you ever noticed that on a hot summer day, the pool is cooler than the hot cement? Or maybe that the ocean is cooler than the hot sand? Let’s look at why that is.

6 We know that different materials heat up at different rates, 1 kg of Gold heat up seven times faster than 1 kg of Aluminum.

7 Different materials also store different amounts of heat energy
Different materials also store different amounts of heat energy. It takes water about 30 times longer to heat than gold, so that means that water stores about 30 times more calories.

8 Specific Heat Capacity
Specific Heat: The amount of heat required to raise the temperature of 1 gram of a substance 1 degree Celsius. Joule-SI unit for work or energy Calorie-A unit of heat and energy equal to the amount of energy requires to raise the temperature of 1 gram of water by 1° Celsius. Specific heat by definition is the heat required to raise the temperature of 1 gram of a substance 1 degree Celsius. A joule is the unit for work or energy and a calorie is the unit of heat and energy equal to the amount of energy required to raise the temperature of 1 gram of water by 1 degree Celsius. So 1 Calorie equals Joules and 1000 Joules equals 1 kilojoule so 4184 joules equals 1 calorie. 1 calorie = J 1,000 J = 1 KJ 4,184 J =1 Calorie

9 Substance Specific Heat J/(g°C)
Water 4.184 Ethanol 2.44 Aluminum 0.897 Granite 0.803 Iron 0.449 Here are some examples of different substances and their Specific Heats, Specific Heat is always written in terms of Joules per grams times Celsius which are the components of the equation. Look that the specific heat of water compared to that of Iron. It takes more energy to heat up one kilogram of water compared to 1 kilogram of iron, and it takes longer for 1 kilogram of water to lose the energy that it has gained.

10 LecturePLUS Timberlake 99
Learning Check A. A substance with a large specific heat 1) heats up quickly 2) heats up slowly B. Sand in the desert is hot in the day, and cool at night. Sand must have a 1) high specific heat ) low specific heat What happens to a substance with a large specific heat? It heats up slowly Sand in the desert is hot in the day and cool at night that means sand must have a low specific heat. LecturePLUS Timberlake 99

11 q = the heat absorbed or released
Equation: q = c x m x ΔT ΔT = Tfinal – Tinitial q = the heat absorbed or released c = the specific heat of the substance m = the mass of the sample in grams ΔT = change in temperature The equation we use for Specific Heat is… The triangle in an equation always represents a change in something.

12 Calorimetry is the process of determining how much energy is present in a substance. A Calorimeter pictured here is something that is used to help determine that energy.

13 1. ) Copper metal has a specific heat (Cp) of 0. 385 J/g⁰C
1.) Copper metal has a specific heat (Cp) of J/g⁰C. Calculate the amount of heat (J) required to raise the temperature of 22.8 g of copper from 20.0⁰C to 875⁰C. q = c x m x ΔT q = .385 J/g⁰C x 22.8 g x 875 ⁰C ⁰C q = J gained Let’s look at this practice problem about Copper. The formula for Specific Heat is

14 2). What is the specific heat of a 25. 0 g substance that absorbs 493
2) What is the specific heat of a 25.0 g substance that absorbs J, and raises the temperature from 12.0⁰C to 34⁰C? q = c x m x ΔT 493.4 J absorbed = c x 25.0 g x 34 ⁰C ⁰C c = .897 J/g⁰C

15 1250 J absorbed = .240 J/g⁰C x m x 15.2⁰C -12.0 ⁰C
3) It takes 1,250 J of energy to heat a certain sample of pure silver from C to C. Calculate the mass of the sample of silver. q = c x m x ΔT 1250 J absorbed = .240 J/g⁰C x m x 15.2⁰C ⁰C m = 1627 g

16 Tomorrow… Be read for a CHECK UP first thing tomorrow! This is how I will know if you are: Doing your homework! Understand the content And what we need to review and reinforce going forward! Now… Use your checklist for chapter 10 to complete your flashcards, you can also look at questions that we discussed in class today. We will come up with more flashcards during opening discussion tomorrow. For tomorrow you should be ready for yet another check up assessment. Again I am looking at who is doing their homework, who is understanding the content, and what we need to still review and or reinforce. Now you should use your new checklist to make questions, since this is for chapter 10, some of the questions may be repetitive and relate to prior content. You may also need to use your prior knowledge from chapter one to answer a few of the questions related to the temperature scales and absolute zero. After our discussion tomorrow you should be able to answer all of the questions and add HOT questions to your flashcards, don’t forget to mark these with a red dot and put them at the top of your stack when they are turned in. HOT questions are questions that require Higher Order Thinking Skills! See you tomorrow!


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