Recent content by James Pelezo

For buffer systems using polyprotic weak acids, a simplification to this conundrum is to assume all H+ come from the 1st ionization step. Except for some of the lower pKa value weak acids, subsequent ionization steps make very little contribution to the total H+ ion concentration. Even so, the...

For what it's worth, I find dividing measurement accuracy & precision into two general areas, experimental and theoretical. Experimental accuracy & precision is limited by the devices used to obtain the measurements. Students are asked to report their concluding values to the accuracy of the...

For organic review, I've found that the following two resources are great fundamental preps for students entering organic. These are ... => Danial Weeks, Pushing Electrons, 4th edn., Saunders Publishing, and => Calvin VanderWerfs, Acids, Bases & Chemistry of the Covalent Bond, Reinhold...

... but I am having a hard time seeing it. Generally, equilibrium stability is affected by one, two or a combination of three factors. These are concentration effects, temperature affects & pressure-volume effects. One way that is used to visualize the effect of concentration and/or...

For academic reasons I find separating energy into three distinctive issues; that is, Kinetic Energy, Potential Energy (or, Positional Energy) and Internal Energy. I must confess that I'm a chemistry professor, not a physics prof, so my distinctions between these energy 'types' is chemistry...

Electron configurations are derived from Atomic Models... The Bohr (Concentric Ring) Model specifies electron configurations with respect to the number of electrons per 'major' energy levels... That is, for any given energy level, the maximum number of electrons a major energy level can hold is...

The sulfuric acid in the lead storage battery is there to react with the Pb(II) ions forming the lead(II) sulfate coatings at the electrodes. This does enhance the voltage but is a unique case. I haven't tried the effect on other systems but I would not expect that to be a universal truth for...

No ... the net cell potential is due to the combination of anode and cathode materials chosen, not the rate of oxidation. Oxidation is a natural product of the chemistry of the combination chosen as is the reduction side of the cell. Boosting oxidation rates to achieve higher charge flow would...

I'd imagine the voltage would also increase if I used a strong acid rather than an electrolyte such as NaCl, yes? Not exactly in that context... Since it hasn’t been mentioned, for voltages outside the ‘Standard Cell Potentials’, one should apply the Nernst Equation. This equation defines...

Yes, but in terms of the cell potentials being always positive and reactive free energy being negative as noted in my reply post. For example, Lithium would always undergo oxidation with respect to all elements listed below it in the activity series, sodium would always undergo oxidation with...

... can the determination of which half-reaction is to be an oxidation or reduction be explained through the spontaneity of the reaction ... ? Yes ... Using standard reduction potentials for the half-reactions, Eocell must be > 0 for the combination of half-reactions used. That is, EoZn/Cu =...

No argument about the accuracy applied, but the original question was how does one differentiate between elements and non-elements... All of the 'giants of science' had to start with some simple, fundamental observations that stirred their interest. Then, as I stated in my comment, applied the...

For the moment, consider an interest in whether or not a substance (an arbitrarily chosen white powder) is an element or compound. What's a simple way to ID this. In early scientific examinations, flame testing would be high on the experimental list. When applied, many substances gave...

Not to over simplify, but if one is trying to introduce a student to the world of atoms and elements the basic premise is 'keep it simple'. Right or wrong, a foundation is established and as one progresses, then add the esoteric issues that further define atomic and/or molecular structure...

Unless you are going to become an ‘expert’ in weights and measures, I’d suggest concentrating on the ones you’ve found in the opening chapters of the text you are studying. The SI system is the most widely applied for academic chemistry topics. As you progress and work problems on specific...