Heat Transfer
Enthalpy & Entropy
Specific Heat
Hess's Law & Bond Enthalpies
Phase changes
100

A Endothermic process absorbs or releases heat?

Absorbs heat.

100

Enthalpy is represented by what symbol?

ΔH

100

What is the equation to calculate heat energy?

Q = mc (delta T)

100

What is the definition of Hess's Law?

The enthalpy change accompanying a chemical reaction is independent of the pathway between the initial and final states. 

100

Sublimation is ________________. 

Phase change from solid to gas with no liquid phase.
200

An exothermic Process releases or absorbs heat?

releases heat.

200

What is the equation to find enthalpy of a reaction?

Delta H = Sum of Delta H (bonds breaking) - Sum of Delta H (bonds forming) 

Delta H = Sum of Delta H (reactants) - Sum of Delta H (products)

200

What does a positive Q value represent?

An endothermic reaction. Heat entering the system.

200

How do we use bond enthalpies of various bonds to calculate enthalpy of a reaction? 

We use the equation...

Delta H reaction = Sum (Delta H of bonds breaking) - Sum (Delta H of bonds forming)

200
Condensation is _________________. 

Phase change from gas to liquid. 

300

The Activation Energy is the energy that is required to:

break the bonds in the reactants.

300

What is the equation to find enthalpy of formation?

Delta H (formation) = Sum Delta H formation (products) - Sum Delta H formation (reactants)
300

An exothermic reaction releases energy(heat), so its Q will be: A) (+) or   B) ( - ) or  C) zero

B. (-) Negative

300

Complete Example #1 - calculating the enthalpy for the reaction on the paper. 

+226.7 kJ

300

Deposition is ______________.

Phase change from gas to solid with no liquid phase.

400
What is Thermal Equilibrium?

When there is no heat transfer between two objects. (Both objects are at the same temperature)

400

What is Entropy and what is its symbol? 

Entropy is the measure of how the available energy is distributed among the particles (disorder of a system).

400

Heat transfers from ____ to ____ objects.

Hot, Cold

400
Complete Example #2 on paper.

-1075 kJ

400

Evaporation (vaporization) is ________________. 

Phase change from liquid to gas. 

500

What is the difference between temperature and heat?

Temperature is a measure of the average kinetic energy of particles.

Heat is a form of energy that flows from something at a higher temperature to something at a lower temperature. 

500

ΔS can be calculated how? 

Delta S = Sum(Delta S of products) = Sum(Delta S of reactants)

500

When 1.20 grams of C6H14 are burnt, the temperature of 250 grams of water is raised by 56 degrees Celsius. Calculate the enthalpy change (Q) when one mole of C6H14 is burnt.

-4200 kJ/mol

500

Calculate the enthalpy change (Delta H) for the reaction on the paper. 

-2831 kJ

500

If a substance undergoes a phase change, its composition also changes. (True or False or Sometimes?)

False