Introduction to pH, pOH, and Kw

What are Acids and Bases?

Below is a Khan Academy video talking about the differences between acids and bases.

This is awesome... Twice.

CSI Online: Eyewitness Basics Websites

Site #1: Art of Crime Scene Detection

Site #2: Spot the Differences

Site #3: Powers of Observation

Site #4: FBI Games -- Choose the Matching Game

Site #5: QUIA: Crime Scene Basics

--From the Worksheet Found at, www.sciencespot.net

Entropy Homework Answers

∆S and ∆G Homework

For the first three reactions below, indicate whether you believe the entropy for

the reaction is positive or negative:

1) ____ NaN3(s) à  ____ Na3N(s) + ____ N2(g)               POSITIVE

2) ____ Al(s) + ____ Br2(l) à ____ AlBr3(s)                    NEGATIVE

3) ____ Hg(l) + ____ O2(g) à ____ HgO(s)                       NEGATIVE

Solve the following problems regarding entropy and the spontaneity of chemical

reactions:

4) A chemical reaction has a ∆Hrxn of – 157 kJ and a ∆Srxn of – 221 J/K.  Is

this reaction spontaneous at 525 K?

ΔG = -157 --  (525)(-0.221)

ΔG = -40.975

YES, this reaction will be SPONTANEOUS BECAUSE,

+ΔG = non-spontaneous

-ΔG = spontaneous

ΔG = 0 = equilibrium

5) At what temperature is the reaction from problem #4 at equilibrium?

0 = -157 – (T)(-0.221)

157 = -(T)(-0.221)

-157 = T(-0.221)

T = 710 K

6) If a chemical reaction is at equilibrium at 298 K and ∆Srxn = -89 J/K, what

is ∆Hrxn for this process?

ΔH = -26.522

7) What is ∆G for the reaction in problem 6 at 398 K?  Is this reaction

spontaneous?

ΔG = 8.9

NO, this reaction is NON-SPONTANEOUS

Potential Energy Diagrams

Calculating Heat of Reaction Using Heats of Formation Answers

Tips:
- Use the steps provided in problem #1 for each problem.
- In problems 3 and 4 you are not solving for the heat of reaction, but rather the heat of formation of one of the molecules.


1. -90.566 kJ
2. -1057.9 kJ
3. -415.5 kJ
4. -157.3 kJ
5. -2069.6 kJ