Chapter 11 Test Flashcards
What is energy?
The capacity or ability for doing work
What do all physical and chemical changes involve?
the absorption or emission of energy (energy changes)
What is heat?
The energy transferred as a result as result of a temperature difference.
What is the symbol for heat?
q
How is heat energy transferred?
Heat (energy) is transferred from the system of higher energy/temp to the system with lower energy/temp.
What is a Joule?
unit of energy and heat
What is a calorie?
the amount of heat required to raise the temperature of 1 gram of pure water 1 oC.
What is the ratio of Joules to calories?
1 cal=4.184 J
What are symbols for calories and Joules?
J and cal
What is a Calorie?
1000 calories = 1kcal, used in our foods
the amount of energy the human body can obtain by chemically breaking down food.
What is the symbol for a Calorie?
C
What are exothermic reactions with respect to heat and energy?
Energy is given off by a reaction, usually in the form of heat. These reactions are usually spontaneous and the products have less energy than the reactants because energy is given off by the system.
What are endothermic reactions with respect to heat and energy?
Energy is absorbed in a reaction. The products of this reaction are of higher energy than the reactants.
What is a catalyst?
speeds up a chemical reaction by lowering the Activation energy.
What is an inhibitor?
slows down a chemical reaction by lowering the Activation energy.
What are the two sides of a chemical reaction equation?
Reactants —– Products
What is a Calorimeter?
instrument used to measure energy given off or absorbed during a physical or chemical change.
What is the Law of Conservation of Energy?
All chemical and physical changes obey this. A law of science that states that energy cannot be created or destroyed, but only changed from one form into another or transferred from one object to another.
What is specific heat?
The amount of heat energy needed to raise the temperature of 1 gram of substance, 1 oC.
What is the symbol for specific heat?
Cp
What kind of specific heat to metals have?
Low
What is heat capacity?
the amount of heat/energy needed to raise the temperature of an object 1.0oC
What is the Cp of ice?
2.11 J/g degrees C
What is the Cp of liquid water?
4.184 J/g degrees C
What is the Cp of water vapor?
2.08 J/g degrees C
What is the specific heat equation?
Specific Heat (Cp) = Heat (J)/ Mass (g) x ΔT (oC)
How to you rearrange the specific heat equation to solve for the heat needed?
q=(m)(Cp)(ΔT)
What is enthalpy of fusion?
the energy required to melt a substance at its melting point
What is enthalpy of solidification?
the energy released when a substance freezes at its freezing point
What is enthalpy of vaporization?
the energy required to vaporize a substance at its boiling point
What is enthalpy of condensation?
the energy released when a substance condenses
What is the symbol for enthalpy of a change of matter state?
∆H
What is boiling point?
the temperature at which the vapor pressure of the liquid is equal to the atmospheric pressure
What is melting point?
the temperature at which the vapor pressure of the solid and liquid phases of a substance is equal
What is freezing point?
the temperature when the vapor pressure of liquid equals the vapor pressure of the solid.
In the water specific heat diagram, describe the change types they are based on heat and energy.
All of these changes are endothermic when they go up (melting, vaporization), but when they go opposite, it is exothermic (condensation, freezing)
What is ∆Hfus for pure water?
334 J/g
What is ∆Hvap for pure water?
2260 J/g
What is ∆Hsolid for pure water?
-334 J/g
What is ∆cont for pure water?
-2260 J/g
