What’s the MATTER: Specific Heat of Matter
description
Transcript of What’s the MATTER: Specific Heat of Matter
![Page 1: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/1.jpg)
What’s the MATTER:Specific Heat of Matter
![Page 2: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/2.jpg)
Matter, Specific Heat of Matter
At the conclusion of our time together, you should be able to:
1. Define specific heat2. Use specific heat to determine energy
changes
![Page 3: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/3.jpg)
Exothermic and Endothermic Processes
Essentially all chemical reactions and changes in physical state involve either:a) release of heat, orb) absorption of heat
![Page 4: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/4.jpg)
Exothermic and Endothermic Processes
In studying heat changes, think of defining these two parts: the system - the part of the
universe on which you focus your attention
the surroundings - includes everything else in the universe
![Page 5: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/5.jpg)
Exothermic and Endothermic Processes
Together, the system and it’s surroundings constitute the universe
Thermochemistry is concerned with the flow of heat from the system to it’s surroundings, and vice-versa.
![Page 6: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/6.jpg)
Exothermic and Endothermic ProcessesHeat flowing out of a system into
it’s surroundings: defined as negative q has a negative value called exothermic
system loses heat (gets cooler) as the surroundings heat up
![Page 7: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/7.jpg)
Exothermic and Endothermic ProcessesHeat flowing into a system from its
surroundings: defined as positive q has a positive value called endothermic
system gains heat (gets warmer) as the surroundings cool down
![Page 8: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/8.jpg)
8
Energy TransformationsHeat - represented by “q”, is energy
that transfers from one object to another, because of a temperature difference between them. only changes can be detected! flows from warmer cooler object
![Page 9: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/9.jpg)
9
Units for Measuring Heat Flow1) A calorie is defined as the quantity of
heat needed to raise the temperature of 1 g of pure water 1 oC. Used except when referring to food a Calorie, (written with a capital C),
always refers to the energy in food 1 Calorie = 1 kilocalorie = 1000 cal.
![Page 10: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/10.jpg)
10
Units for Measuring Heat Flow
2) The calorie is also related to the Joule, the SI unit of heat and energy
named after James Prescott Joule 4.184 J = 1 cal
Heat Capacity - the amount of heat needed to increase the temperature of an object exactly 1 oC
Depends on both the object’s mass and its chemical composition
![Page 11: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/11.jpg)
11
Heat Capacity and Specific HeatSpecific Heat Capacity
(abbreviated “C”) - the amount of heat it takes to raise the temperature of 1 gram of the substance by 1 oC often called simply “Specific Heat”
Water has a HUGE value, when it is compared to other chemicals
![Page 12: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/12.jpg)
Note the tremendous difference in
Specific Heat.
Water’s value is
VERY HIGH.
![Page 13: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/13.jpg)
13
Heat Capacity and Specific HeatFor water, C = 4.18 J/(g oC) in
Joules, and C = 1.00 cal/(g oC) in calories.
Thus, for water: it takes a long time to heat up,
and it takes a long time to cool off!
Water is used as a coolant!
![Page 14: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/14.jpg)
14
Heat Capacity and Specific HeatTo calculate, use the formula:
q = mass (in grams) x T x Cheat is abbreviated as “q”T = change in temperatureC = Specific Heat
Units are either: J/(g oC) or cal/(g oC)
![Page 15: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/15.jpg)
Practice #1
q = cp x m x t: q = 59.912 J cp = x m = 36.359 g t = 152.0 oC59.912 J = (x)(36.359 g)(152.0 oC)
= 0.01084 J/g oC
![Page 16: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/16.jpg)
Practice #2 q = cp x m x t:
q = -800. J cp = 0.4210 J/g oC m = 73.174 g t = (x – 102.0 oC)-800. J = 0.4210 J/goC (73.174 g)(x – 102.0
oC)-800. = 30.81x – 31422342 = 30.81x
= 76.0 oC
![Page 17: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/17.jpg)
Matter, Specific Heat of Matter
Let’s see if you can :
1. Define specific heat2. Use specific heat to determine energy
changes
![Page 18: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/18.jpg)
Define Specific Heat
Specific Heat – the amount of energy required to raise the temperature of one gram of a substance by one Celsius degree or one Kelvin
![Page 19: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/19.jpg)
Practice #3 q = cp x m x t:
q = -185.4 J cp = 0.440 J/g oC m = x g t = -1475 oC-185.4 J = (0.440 J/goC )(x)(-1475 oC)-185.4 J = -649 Jg
= 0.29 g
![Page 20: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/20.jpg)
Practice #4 q = cp x m x t:
q = x J cp = 0.0335 cal/goC (4.184 J/cal) m = 152.00 g t = -51.5oCx = (0.140164 J/goC )(152.00 g)(-51.5 oC) = -1.10 x 103 J
![Page 21: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/21.jpg)
CalorimetryCalorimetry - the measurement of
the heat into or out of a system for chemical and physical processes. Based on the fact that the heat
released = the heat absorbedThe device used to measure the
absorption or release of heat in chemical or physical processes is called a “Calorimeter”
![Page 22: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/22.jpg)
Calorimetry Foam cups are excellent heat
insulators, and are commonly used as simple calorimeters under constant pressure.
For systems at constant pressure, the “heat content” is the same as a property called Enthalpy (H) of the system
(They are good because they are well-insulated.)
![Page 23: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/23.jpg)
A foam cup calorimeter – here, two cups are nestled together for better insulation
![Page 24: What’s the MATTER: Specific Heat of Matter](https://reader035.fdocuments.in/reader035/viewer/2022081505/56816124550346895dd07e98/html5/thumbnails/24.jpg)
Calorimetry
Changes in enthalpy = Hq = H These terms will be used
interchangeably in this textbookThus, q = H = m x C x T H is negative for an exothermic
reaction H is positive for an endothermic
reaction