Exam 2 Lecture 3

Question 1

Determination of ΔH for a reaction

Answer 1

• • Determine experimentally: calorimetry
• • Calculate from enthalpy data for other reactions

Question 2

Experimental determination of ΔH for a reaction

Answer 2

2

Question 3

Specific heat

Answer 3

3

Question 4

Experimental determination of ΔH for a reaction A + B –> C + D What is the system?`

Answer 4

A,B,C,D

Question 5

Experimental determination of ΔH for a reaction A + B –> C + D What is the surroundings?`

Answer 5

the water inside the calorimeter

Question 6

Experimental determination of ΔH for a reaction A + B –> C + D – Exothermic reaction:

Answer 6

• heat flows from system to water
• (T of water goes up)

Question 7

Experimental determination of ΔH for a reaction A + B –> C + D –endothermic reaction:

Answer 7

• heat flows from water to system
• (T of water goes down)

Question 8

By knowing the__,_____________ you can determine ΔH for the reaction

Answer 8

• mass of the water,
• the temperature change,
• the specific heat of the surroundings (water),

Question 9

Experimental determination of ΔH for a reaction STEPS

Answer 9

• `• Carry out reaction
• • Measure temperature change of reaction
• • Know specific heat of calorimeter
• • Know mass of heat absorbing material in the calorimeter

Question 10

ΔH values should be reported relative to _______-of the balanced chemical equation

Answer 10

the stoichiometry

Question 11

Hess’ Law: ΔH for a given reaction is x_________, or _______that add together to give the reaction of interest

Answer 11

the sum of the ΔH values for each individual step in the reaction,

the sum of ΔH values for a sequence of reactions

Question 12

If you reverse the products and reactants, you must_____ of the formula change in enthalpy

Answer 12

reverse the sing

Question 13

Standard State

Answer 13

≡ 25° C and one atmosphere of pressure

Question 14

The “standard state form” of an element

Answer 14

is the form most stable at

• 25°
• one atmosphere of pressure

Question 15

Diatomic Gasses

Answer 15

Question 16

Diatomic Solid

Answer 16

Question 17

Empirical

Answer 17

Question 18

Octatonic molecule

Answer 18

Question 19

Answer 19

“Not”