quantity of heat needed to raise the temperature of 1 g of water by 1 C
calorie
SI unit of energy
Joule
quantity of heat needed to change the temperature of 1 g of a substance by 1�C
specific heat
Quantity of heat needed to change the temperature of an object by 1C
heat capacity
device used to measure the heat absorbed or released during a chemical reaction during a chemical or physical process
calorimeter
heat content of a system at constant pressure
enthalpy
the enthalpy change for a chemical reaction exactly as it is written
heat of reaction
the enthalpy change caused by dissolving a substance
heat of solution
the energy required to melt a solid at its melting point
heat of fusion
the change in enthalpy that accompanies the formation of a compound from its elements
heat of formation
states that if you can add two or more thermochemical equations to produce a final equation for a reaction, then the sum of the enthalpy changes for the individual reactions is the enthalpy change for the final reaction
Hess's Law
A piece of metal is heated, then submerged in cool water. Which statement below describes what happens?
the temperature of the water will increase and the temperature of the metal will decrease
How does a calorie compare to a joule?
a calorie is larger than a joule
What would likely happen if you were to touch the flask in which an endothermic reaction were occurring?
the flask would probably feel cooler than before the reaction started
When energy is changed from one form to another
all of the energy can be accounted for
If heat is released by a chemical system, an equal amount of heat will be
absorbed by the surroundings
In an exothermic reaction, the energy stored in the chemical bonds of the reactants is
greater than the energy stored in the bonds of the products
process that absorbs heat
endothermic
When your body breaks down sugar completely, how much heat is released compared to burning the same amount of sugar in a flame?
the body releases the same amount of heat
The quantity of heat required to change the temperature of 1 g of a substance by 1 C is defined as ____.
specific heat
A piece of candy has 5 Calories (or 5000 calories). If it could be burned, leaving nothing but carbon dioxide and water, how much heat would it give off?
5 kilocalories
how many joules are in 148 calories
619 J
how can you describe the specific heat of olive oil if it takes approximately 420 joules of heat to raise the temperature of 7 g of olive oil by 30�C
less than the specific heat of water
the amount of heat needed to melt one mole of a solid at a constant temperature
molar heat of fusion
During a phase change, the temperature of a substance
remains constant
To calculate the amount of heat absorbed as a substance melts, which of the following information is NOT needed?
the density of the sample
what is the heat of solution
the amount of heat absorbed or released when a solid dissolves
The greater the average kinetic energy of the particles in a sample of matter,
higher temperature
energy is measured in units of
Joules
for an exothermic equation, <| H is always
negative
in an endothermic reaction, the total energy at the beginning of the reaction
less than the total energy at the end of the reaction
For an exothermic reaction, the products
are at a lower energy level than the reactants
<| H is always positive for a
endothermic reaction
what best describes temperature
a measure of the average kinetic energy of the particles in a sample of matter
the change in H of a reaction is measured by
subtracting H of the reactants from the H of products
the minimum energy colliding particles must have an order to react
activation energy
arrangement of atoms at the peak of an energy barrier
activated complex
a substance that lowers the activation energy
catalyst
a substance that raises the activation energy
inhibitor
which expression a reaction rate
moles/times
At what stage of a reaction do atoms have the highest energy?
transition state stage
Why does a higher temperature cause a reaction to go faster?
There are more collisions per second and the collisions are of greater energy.
Why does a higher concentration make a reaction faster?
there are more collisions per second only
Includes all elementary reactions of a complex reaction
reaction mechanism
Reactants are converted to products in a single step
elementary reaction