Specific heat
Download
1 / 13

Specific Heat - PowerPoint PPT Presentation


  • 52 Views
  • Uploaded on

Specific Heat . Da Procida: Year 4. Lesson 3. Review. Last week: Internal Energy (U) : total energy of a system. Heat (Q) : heat added to the system (positive) or taken away from the system. (negative) Work (W) : Work done by the system (negative) or work done on the system (positive).

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

PowerPoint Slideshow about ' Specific Heat ' - hadassah-rivas


An Image/Link below is provided (as is) to download presentation

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
Specific heat
Specific Heat

  • Da Procida: Year 4

Lesson 3


Review
Review

Last week:

Internal Energy (U) : total energy of a system.

Heat (Q) : heat added to the system (positive) or taken away from the system. (negative)

Work (W) : Work done by the system (negative) or work done on the system (positive).


Concept question
Concept Question

What is heat?

1) A measure of how hot or cold something is.

2) A basketball team from Boston.

3) Energy transferred due to a temperature difference.

4) A quantity measured in degrees Kelvin.


Answer
Answer

What is heat?

1) A measure of how hot or cold something is.

2) A basketball team from Boston.

3) Energy transferred due to a temperature difference.

4) A quantity measured in degrees Kelvin.


Units of heat
Units of Heat

Heat is a form of energy, and so we measure it with either Joules or Calories.

4.184 Joules = 1 Calorie

When do we often talk about calories?


Food!

We talk about kilocalories when we talk about food.

Why?

Our bodies require a certain amount of energy to function - about 2000 kcal a day.


What is a calorie exactly
What is a “Calorie,” exactly?

1 Calorie

is defined to be the amount of energy that it takes to heat 1 gram of water up by 1 degree.


Heating different materials
Heating Different Materials

During the summer time, when you walk from the sand into the ocean, which is hotter?

Why? Is there a different amount of heat being applied?


Heat capacity
Heat Capacity

Every single substance has a quantity that we call heat capacity.

This quantity refers to how quickly or how slowly something will heat up.

Although the same amount of heat is applied to the water and sand, the sand heats up more quickly.

Pizza: tomato sauce heats up faster than cheese, so we burn our mouths from the tomato sauce!


Specific heat capacity
Specific Heat Capacity

If we look at the heat capacity per mass, we call this specific heat capacity.

A high specific heat capacity means that something takes a long time to heat up, while a low specific heat capacity means something heats up quickly.

Water has an extremely high specific heat capacity, while metals do not.


Calculating specific heat capacity

Calculating Specific Heat Capacity


Specific heat capacity of water
Specific Heat Capacity of Water

The specific heat capacity of a material is usually not a constant - it changes with temperature.

However, we generally only work around 15 deg. C, so we take the specific heat capacity of water as 1 C/g, or 4.184 J/g.


Problems
Problems

How much heat is absorbed when 500. g of water , Cp = 4.184 J/goC, goes from 25.0 oC to 35.0 oC?

How much heat is absorbed when 500. g of copper, Cp = 0.385 J/goC ,  goes from 25.0 oC to 35.0 oC?

Casey’s insulated foam cup is filled with .150kg of coffee (c=4187J/kg°C) that is too hot to drink so she adds .01kg of milk (c=3800J/(kg°C)) at 5.0°C. If the coffee has an initial temperature of 70 °C, how hot is the coffee after the milk is added? (What is the final temperature of the coffee and milk mixture?)

Rosetta has made a bowl of tagliolini (c=4187J/kg°C) which she ladles from a pot into a glass bowl. If .6kg of soup at 90°C is placed in a .2kg glass bowl (c=840J/kg°C) that is initially at 20°C, what will be the temperature of the soup when the soup and the bowl have reached equilibrium?


ad