Unit B: Thermochemical Changes Module 4

Question 1

Heat absorbed by water equation

Answer 1

Q=mcdeltat

Question 2

Isolated System

Answer 2

energy and matter cannot move in or out

Question 3

Calorimetry

Answer 3

process of measuring energy changes in an isolated system

Question 4

Laws of Thermodynamics (x2)

Answer 4

• energy cannot be created or destroyed

- heat transfers naturally from warmer to cooler areas

Question 5

Thermal Energy (Q)

Answer 5

represents the total kinetic energy of the entities of a substance

Question 6

Specific Heat Capacity

Answer 6

amount of energy needed to raise the temp of 1 g of substance by 1 oC

Question 7

Assumptions when using a calorimeter

Answer 7

• thermal energy gained by the container, lid , stirrer can be ignored/ are negligible
• calorimeters aren’t 100% efficient, some heat is always lost but its negligible
• aqueous solutions have the same density (1g/mL) and specific heat capacity as water

Question 8

Moles equation

Answer 8

n= m (mass) / M (molar mass)

Question 9

Calorimeter Inefficiency Equation (percent error)

Answer 9

experimental value -predicted value / predicted value x 100

Question 10

Hess’s Law

Answer 10

if you combine the standard enthalpy change values of known reactions it will equal the standard enthalpy change of the final reaction (steps=final product)

Question 11

Formation Reaction (deltafH)

Answer 11

1 mole compound is formed from its elements at standard conditions

Question 12

Thermal Stability

Answer 12

tendency of a compound to resist decomposition when heated

if a compound takes more energy to decompose its more stable

Question 13

Hess’s Law Predicting Enthalpy Equation

Answer 13

deltarH=molar enthalpy of formation of products - molar enthalpy of formation of reactants