Monday May, 23

Today's class started off with Mr. H giving back our redox quiz we took last Friday. Everyone did really well and it was our best quiz so far. Yay! After this Mr. H talked to us about the lab we are going to do Wednesday which involves using a fruit to make a battery. He explained that someone from your groups of two should bring in a JUICY fruit; oranges, kiwi, lemon and limes are all good choices. Dimitry already brought his fruit for the lab, which he bought from the Soviet market this past weekend. He also bought some borscht from the market too. Once Mr. H finished explaining the lab, he talked about what we are going to do tomorrow. We are going to take a practice Final Exam that consists of 80 questions in order to prepare for the actual final. He said that since there are a lot of problems we are probably not going to finish the whole thing but that's okay. Mr. H did however share some very important information concerning the practice final: DON'T WRITE on the booklet. If one were to write on the booklet they are putting their life in danger because the booklet is pressurized and if you write on it, it will activate an explosive that will blow up the booklet and you. But only you.

After all this blowing up people and borscht, we almost started our lesson for today, until Will found a beetle. Him and Mr. H decided to take the beetle outside to a better place. I think he died (or feigned death five times). Finally we started in our packet on page 9 with a review of the reduction table. The key rules to follow while using a reduction table are:
1. Elements higher on the table are easily reduced, but least likely to oxidize.
2. Elements lower on the table are least likely to reduce, but are easily oxidized.

Then class was interrupted again because Dan lost his packet, he probably sold it. Dan also received a note which means he did something wrong again.

We went on to page 10 where Mr. H taught us how to calculate the volts of a standard reduction potential for any oxidation-reduction reaction. The first problem involved writing two half reactions, listing the standard reduction potentials values, and calculating the overall cell potentials.

Step 1: Write the oxidation and reduction equations:

O: Al(s)----> Al3+(aq) +3e-

R: 2e- +Zn2+(aq)----> Zn(s)

Step 2: Find the standard reduction potentials for the two elements Al and Zn. For the anode, Al, the oxidation potential = +1.66 V. The reason this number is positive is because any oxidation reaction is simply the reverse of the reduction reaction listed in the table; -1.66=+1.66. The reduction potential =-0.76 V for Zn

Step 3: Then you add the two values together to get the cell potential which is +0.90 V.

After this, we went on to page 11 and did problem 8 together. For 8, you had to use standard reduction potentials from the table and the principle that is too long to type. (See page 11 at the top).

Step 1: Find the volt values for Cd and Ag: -0.40 for Cd and +0.80 for Ag.

Step 2: Determine which reaction is found lowest in the table of reduction potentials because this reaction is most likely to occur as an oxidation reaction: Cd.

Step 3: You can now deduce that Cd is oxidized and Ag+ is reduced. Then you can use this information to figure out that Cd is the anode and Ag+ is the cathode.

Step 4: The direction of electron flow is from left to right, and the direction is always from the anode to the cathode.

Step 5: Write the two half equations:

O: Cd(s)----> Cd2+(aq) +2e-

R: 1e- + Ag+(aq)----> Ag(s)

Step 6: Add the two standard reduction potentials together to figure out the cell potential and the answer is +1.20V.

We finished class today by Mr. H giving us a AFKE Quiz (Fake Quiz), numbers 9 and 10 on page 11.

Homework: The redox webassign was moved back to Thursday and their is also a quiz on Thursday