Study your flashcards anywhere!

Download the official Cram app for free >

  • Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off

How to study your flashcards.

Right/Left arrow keys: Navigate between flashcards.right arrow keyleft arrow key

Up/Down arrow keys: Flip the card between the front and back.down keyup key

H key: Show hint (3rd side).h key

A key: Read text to speech.a key


Play button


Play button




Click to flip

102 Cards in this Set

  • Front
  • Back
melting ice and boiling water _______ water
concerned with the heat changes that occur during chemical reactions
the capacity for doing wrk or supplying heat
unlike matter, energy is
weightless, odorless, and tasteless
energy stored within the structural units of chemical substances
chemical potential energy
what contains a significant amount of chemical potential energy
dfference substances store
diferent amounts of energy
what determines the amount of energy stored in the substance
the amount of energy and their arrangement in the substance
what is represented by q
what is the energy that transfers from one object to another because of a temperature difference between them
heat cannot be detected by
the senses or by instruments
only ______ caused by heat can be detected
one of the effects of adding heat is
a rise in the temperature of objects
heat always flows from a
warmer objecct to a cooler object
what happens if two objects remain in contact
heat will flow from the warmer object to the cooler object until the temperature of both objects is the same
all chemical reactions and changes in physical state involve
either the release or the absorption of heat
in studying heat changes, it is useful to define a _______ as the part of the universe on which you focus your attention
includes everything else in the universe
the surroundings
what is a good approximation to consider in thermochemical experiments
the region in the immediate vicinity of the system as the surroundings
together, the system and its surroundings constitute the
what is a major goal of studying thermochemistry
to examine the flow of heat from the system to its surroundings, or the flow o heat from the surroundings to the system
states that in any chemical or physical process, energy is neither created nor destroyed
law of conservation of energy
all of the energy involved in a process can be accounted for as
work, stored energy, or heat
in thermochemical calculations the direction of the heat flow is given from
the point of view of the system
heat flowing into a system from its surroundings is defined as
a process that absorbs heat from the surroundings is called an
endothermic process
what happens in an endothermic process
the system gains heat as the surroundings cool down
heat flowing out of te system into its surroundings is
a process that releases heat to its surroundings is called an
exothermic process
what occurs in an exothermic process
the system loses heat as the surroundings heat up
exothermic (chart)
heat flows out of the system

heat change < 0 (negative)
heat flows into the system

heat change > 0 (positive)
what does it mean to "burn calories"
during exercise, your body generates heat, and this heat is measured in units called calories
how is the heat generated in your body
as your body breaks down sugars and fats into carbon dioxide and water
what accomplishes the same result as if there were an actual fire burning the sugars and fats within your body
chemical reactions
In breaking down 10 grams of sugar, your body generates a certain amount of heat.

When would the same amount of heat be produced?
if 10 grams of sugar were completely burned in a fire, producing carbon dioxide and water.
what is defined as the quantity of heat needed to raise the temperature of 1 gram of pure water 1 *C
a calorie
what refers to the energy in food
dietary Calorie
when are calories not used
when referring to energy contained in food
1 dietary Calorie =
1 kilocalorie
1 kilocalorie =
1000 calories
what does the statement "10 grams of sugar has 41 Calories" mean
that 10 grams of sugar releases 41 kilocalories of heat when completely burned to produce carbon dioxide and water
what is a calorie related to
a joule
what is the SI unit of heat and energy
who is the joule named after
English physicist James Prescott Joule
a joule is slightly less than _____ of a calorie
1 joule of heat raises the temperature of 1 gram of pure water
0.2390 *C
1 J =
0.2390 cal
4.184 J =
1 cal
the amount of heat needed to increase the temperature of an object exactly 1 *C is the ___________ of that object
heat capacity
what does the heat capacity of an object depend on
its mass as well as its chemical composition
the greater the mass of an object
the greater its heat capacity
different substances with the same mass may have
different heat capacities
_________________ or _________ of a substance is the amount of heat it takes to raise the temperature of 1 g of the substance 1 *C
specific heat capacity
specific heat
what has a very high specific heat compared to other substances in the table
what has low specific heats
Heat affects the temperature of objects with a high specific heat much less than
the temperature of those with a low specific heat
just as it takes a lot of heat to raise the temperature of water,
water also releases a lot of heat as it cools
how do you calculate the specific heat of a substance
you divide the heat input by the temperature change times the mass of the substance
specific heat
delta T
change in temperature
how is delta T calculated
delta T = Tf - Ti
final temperature
initial temperature
C =
q / m x delta T

heat(joules or calories) / mass(g) x change in temp (*C)
specific heat may be expressed in terms of
joules or calories
units of specific heat
J/(g x *C)

cal/(g x *C)
most physical and chemical changes you will encounter occur at
constant pressure
a variable that takes constant pressure into account
how can you measure the energy changes that accompany chemical and physical processes?
by defining a thermodynamic variable
heat that is released or absorbed during many chemical reactions can be measured by
the accurate and precise measurement of heat change for chemical and physical processes
in calorimetry, the heat released by the system is equal to
the heat absorbed by its surroundings
to measure heat changes accurately and precisely, the processes must be carred out in an
insulated container
the insulated device used to measure the absorption or release of heat in chemical and physical processes is called a
what is an example of an excellent heat insulator and why
foam cups because they do not let much heat in or out
for systems at constant pressure, the heat conents is the same as a property called _____ of the system
enthalpy (H)
heat changes for reactions carried out at constant pressure are the same as
changes in enthalpy, symbolized as delta H
q =
delta H
delta H =
m x C x delta T
q = delta H = m x C x delta T
equation for the heat change in a chemical reaction carried out in aqueous solution
delta H
heat change
the sign of delta H is negative for
exothermic reaction
the sign delta H is positive for
endothermic reaction
How do you measure the heat change for a reaction in aqueous solution in a foam cup calorimeter
dissolve the reacting chemicals (the system) in known volumes of water (the surroundings)

then measure the initial temperature of each solution and mix the solutions in the foam cup

after the reaction is complete, measure the final temperature of the mixed solutions
because you know the inital and final temperatures of water, you can calculate the
heat released or absorbed in the reaction using the equation for specific heat
calorimetry experiments can also be performed at constant pressure using a device called a
bomb calorimeter
measures the heat released from burning a compound
bomb calorimeter
the calorimeter is a ____ system
what does "the calorimeter is a closed system" mean
the mass of the system is constant
you can treat heat change in a chemical reaction like any other
reactant or product in a chemical equation
an equation that includes the heat change is called a
thermochemical equation
the heat change for the equation exactly as its written
heat of reaction
you will usually see heats of reaction reported as
delta H
the standard conditions are that the reaction is carried out at
101.3 kPa (1 atmosphere)
if the reaction is endothermic, where does the heat change go in the equation
left side
if the reaction is exothermic, where does the heat change go in the equation
right side
the amount of heat released or absorbed during a reaction depends on
the number of moles of the reactants involved
the heat reaction for the complete burning of one mole of a substance
heat of combustion
in endothermic processes, the potential energy of the product is
higher than the potential energy of the reactants