Chapter 6 (section 6)

Question 1

the enthalpy of a system is …?

Answer 1

the sum of its internal energy and the product of its pressure and volume

H = U + PV

Question 2

What is the equation for the change of the enthalpy of a system?

Answer 2

ΔH = ΔU + PΔV

Question 3

Define exothermic reaction

Answer 3

a chemical reaction that releases heat into its surroundings; for an exothermic reaction, ∆H < 0

Question 4

A positive ΔH indicates …?

Answer 4

heat flows into the system as the reaction occurs

Question 5

A negative ΔH indicates …?

Answer 5

heats flows out of the system as a reaction occurs

Question 6

A positive ΔH means the reaction is _____

Answer 6

endothermic

Question 7

A negative ΔH means the reaction is ___

Answer 7

exothermic

Question 8

Define endothermic reaction

Answer 8

a chemical reaction that absobrbs heat from its suroroundings; for an endothermic reaction, ∆H > 0

Question 9

What is symbol the enthalpy change of a reaction?

Answer 9

ΔᵣH

Question 10

The enthaply change of reaction is also called _____ __ ____ or ____ ____

Answer 10

enthalpy of reaction

heat of reaction

Question 11

Define heat of reaction

Answer 11

the enthalpy change for a chemical reaction

Question 12

Define entahlpy of reaction

Answer 12

the enthalpy change for a chemical reaction

Question 13

The enthalpy of the reaction is a ____ property. This means it depends on…?

Answer 13

extensive

the amount of material undergoing the reaction.

Question 14

Define enthalpy (H)

Answer 14

The sum of the internal energy of a system and the product of its pressure and volume; the energy associated with the breaking and forming of bonds in a chemical equation

Question 15

Since internal energy, pressure, and volume are all state functions, enthaply is….?

Answer 15

also a state function

Question 16

If pressure is constant, what is the change in enthalpy equal to?

Answer 16

Temperature

Question 17

The value of ∆ᵣH for a chemical reaction is….?

Answer 17

the amount of heat absorbed or evolved in the reaction under conditions of constant pressure

Question 18

Where does energy come from in an exothermic reaction seeing as both the temperature of the system and the surroundings rises?

Answer 18

The energy comes from bonds breaking and the forming in a way which lowers the potential energy of the system.

Question 19

Where does the energy go in an endothermic reaction seeing as both the temperature of the system and the surroundings drops?

Answer 19

The energy goes into breaking bonds and then forming bonds of higher potential energy increasing the potential energy of the system.