Question from the notes on stoichometry

Why do we not mix two or several oxidising agents into the same reaction? Will it alter the reaction results and cause it to be inaccurate?

Reflections for 19/2/2010

3. I learnt that comparing ratio to 1 is always easier.

2. I are impressed upon the need to take note if the question requires the comparison between nucleus or atoms.

1. I learnt that I need to glance across the entire list of ionisation energy to decide where is the point when the ionisation energy changes drastically.

2. If the atomic radius of two elements from the same period changes due to the change in nuclear charge, why do we still need to explain the fact that the atomic radius changes?

1. A nucleus is positively charged, therefore the beam of nucleus will be attracted towards the negative plate. If an atom is used and it is electrically neutral, does it mean that the beam does not deflect?

Reflections for 18/2/2010

3. I learnt about Ionisation Energy and understood that ionisation energy is inversly proportionate to energy of the principal quantum shell. The higher the energy, the lower the ionisation energy.
2. I became clearer about the terminologies. Principal quantum shells are the equivalent of the shells we learnt about in higher secondary level.
1. Deflection is proportional to charge and inversely proportional to mass.

2. What does the energy of the principal quantum shell refer to? Does it represent the energy the electrons possess?
1. When asked to explain why the ionisation energies of elements from two different periods are different, do I need to state that "nuclear charge and screening effect increases simultaneously, therefore there are no significant difference between the effective nuclear charge of the two elements"?

Reflections of past lessons

3. I understood the use of indicators to identify the amount of products formed and to use their respective equations in solving problems.
2. I learnt how to balance redox chemical reactions.
1. I understand how to calculate amount of substance from different volumes. (mole concept :) )

2. I'm still unclear about how to differentiate between a alkaline medium and acidic medium.
1. I'm still unsure about the use of mediums.

1. Today's (8/2/2010) practical (theory section) was extremely extremely confusing! I'm not sure how to solve double indicators titration.

Sidenote: I think your teaching is really clear! You are effective in identifying our key problems and then rectifying them. Although the pace is a little fast, I usually understand everything you're going through. :)

Practical 2 reflection

Why I couldn't get the results?

I probably contaminated the solution when I placed the uncleaned pipette into the fixed volumetric flask, in an attempt to rinse my pipette with the solution.

26/1/2010

4. I learnt that the volume of the solution does not increase as the solid dissolves in it. (I'm still not sure why)
3. I learnt how to use graphical illustrations to determine the equivalence point.
2. I learnt the terms "titrant" and "aliquot".
1. I understood what the first contraction and second contraction meant. (example 24)

2. I need more practices regarding the use of the empirical formula table to solve questions (i.e. when to use it and how to use it)
1. I'm not sure why the volume of solution does not increase as the solid dissolves in it.

1. Today's tutorial was rather fast. I didn't have time to think about the current question and we're moving on to the next problem already. :(

Lesson on 22/1/2010

3. I learnt about Eudiometry. It's new to me. I find it useful that the general equation can be derived.
2. The lesson reinforced that actual yield < theoretical yield. I also learnt the term stoichiometric amount, which is the exact amount of a substance  required/produced in a chemical reaction, as calculated by the mole ratio.
1. I understood that mole ratio=volume ratio. Hence, when the volumes of two required compounds are not available, we can use their amounts of substance.

2. I'm still unsure what are the chemicals that can be reacted by CO2 and excess O2 to remove CO2 in Eudiometry.
1. I still do not know what the two contractions represent. (example 24)