Week 14

Discuss one aspect of a comparison of a voltaic cell and an electrolytic cell.

In other words, we want to compare and contrast these two types of cells. The first person to respond choose one aspect to discuss and then the next person choose another aspect, etc.

Week 13 Question 2

Read the following article. What would you be looking for in a car that runs on a hydrogen-oxygen fuel cell?

http://phys.org/news/2014-03-nrel-hydrogen-fuel-cells.html

Week 13 Question 1

What is one concept that you are having difficulty with in Chapter 17? Why do you think that you are struggling with this concept? If you are not struggling with any topic, think of one that you think causes problems for a student and explain why.

Week 12

Start with the following question. We will make sure it is answered correctly before posting another question. If you believe that the person before you has not answered it correctly, give your answer and reasoning.

If CaCO₃, CaO and 1.0 M CO₂ are placed in a flask, will the reaction release heat energy or require heat energy at 25°C. The (delta)G°_rxn = 179.2 kJ and the (delta)H°_rxn is 131.4 kJ. Explain your reasoning!

                        CaCO₃(s)  <---->   CaO(s)  +  CO₂(g)

Week 11

A student is having issues with determining the pH at the equivalence point in a titration of a weak acid with a strong base. How would you explain the process of making this determination?

Answer this question and then write an issue that someone would have with the material in Chapter 16 so that the next student can explain that issue.

Week 10 Question 2

When doing a titration of a polyprotic acid, one starts with a solution of the polyprotic acid in a flask and incrementally adds titrant (strong base such as NaOH) to the solution. The pH can be calculated at various points in the titration, starting with zero added titrant. Some very useful points are the half-equivalence point, the first equivalence point, half way to the second equivalence point and the second equivalence point. 

Using the system of 25.0 mL of 0.050 M malonic acid, H₂C₃H₂O₄ titrated with 0.025 M NaOH, calculate the pH at the following points: 

    First person: zero added NaOH (initial point in the titration)

    Second person: first half equivalence point

    Third person:   first equivalence point

    Fourth person: second half equivalence point

    Fifth person:  second equivalence point

    Sixth person: after adding 150 mL of the NaOH

If we finish with this, I will put up a second system.

Week 10 Question 1

Determine the pK_x (meaning either pK_a or pK_b based upon whether it is an acid or a base) of the following species in solution, then choose another compound for the next person to determine the pK_xvalue.

(CH₃)₃NH⁺