Monthly Archives: September 2013

Dilution Problems

This video covers a particular type of problem that every teacher asks. There are two versions. One asks you to calculate the concentration of a solution created by diluting an existing solution with water, usually using the equation M1V1=M2V2. The other asks you the concentration of a solution formed by combining two solutions of different concentrations.

This video appears on the page: Molarity, Molality, Concentration

Mass Percentage, ppm, Mole Fraction, etc

This video covers all the obscure units of concentration that you'll see on the test in this chapter, but then never see again until the final or AP exam.

This video appears on the page: Molarity, Molality, Concentration

Molarity vs Molality

These are the two most common units for concentration, and unfortunately they're also the most confusing since they're exactly the same word except for one letter. This video explains how to calculate both, how to spot the difference, how they are handled differently in the lab, and the types of questions your teacher is likely to put on the test.

This video appears on the page: Molarity, Molality, Concentration

Molarity, Molality, Concentration

Also covered: parts per million (ppm), parts per billion (ppb), mass ratio (wt/wt), mole ratio (X), mass percent, and those dilution problems where you have to calculate the concentration of a solution after it's been combined with another.

Part of the course(s): Chemistry-General

Ionization Energy Calculations Using Rydberg Equation

One of the many uses of the Rydberg equation (oh what a wonderful equation!) is calculating the ionization energy of a hydrogen atom. What fun! What splendor! Quick man, to the calculators!

This video appears on the page: Ionization Energy & Electron Affinity

Ionization Energy & Electron Affinity on Periodic Table

Sort of like what happened with electronegativity, the periodic table won't give you a number for ionization energy of each element. But almost all chemistry teachers require you to know the general trends of ionization energy, and you'll need to be able to compare two atoms and say which one has a higher first and second ionization energy.

This video appears on the page: Ionization Energy & Electron Affinity

Ionization Energy & Electron Affinity

This chapter explains what ionization energy and electron affinity are, how to predict them based on the periodic table, and how to calculate them using Rydberg's equation.

Part of the course(s): Chemistry-General

Rydberg Equation

Rydberg's equation allows you to calculate the energy of each of the orbitals of a hydrogen atom. Not enthralling stuff, no doubt, but you can use it to calculate the absorption and emission spectra of atoms, if you're into that.

This video appears on the page: Absorption & Emission Spectra

What Are Absorption & Emission Spectra

This video explains what the heck these "spectra" are, and shows you how to solve the most common problem type associated with these, where you're given the energy levels of an atom (usually hydrogen) and then are asked the frequency or energy of a photon which would excite an electron to jump from one level to another.

This video appears on the page: Absorption & Emission Spectra

Absorption & Emission Spectra

This chapter explains how to calculate the energy, wavelength and frequency of photons which can be absorbed or emitted by electrons in hydrogen, using orbital energies or Rydberg's equation.

Part of the course(s): Physics ,Chemistry-General

Electron Volts

A strange little unit of energy that's only used when physicists are talking about photons and particles, this video explains what they are and how to convert to them from Joules. Btw, hilarious science jokes in this video.

This video appears on the page: Photons & Light

Photon Energy & Planck's Constant

By the end of this video, my hope for you is that every time you see the words "photon" and "energy" in the same sentence -- even if you're in the grocery store -- you'll immediately think of the equation E=hf.

This video appears on the page: Photons & Light

The Electromagnetic Spectrum

Most physics and chemistry teachers will expect you to know off the top of your head whether red or purple light has a longer wavelength, what the "visible spectrum" is, and how X-rays and UV-rays stack up. This video covers the whole E&M Spectrum, and gets you up to speed with what very well might be a question on your next test.

This video appears on the page: Photons & Light

Frequency & Wavelength of Light

This video covers what wavelength and frequency are, and also how to calculate them from the equation: speed of light = (wavelength) x (frequency).

This video appears on the page: Photons & Light

Photons & Light

This chapter covers wavelength, frequency, electromagnetic spectrum (E&M), Planck's constant, energy of photons, and electron volts (eV, keV).

Part of the course(s): Physics ,Chemistry-General

Quantum Numbers

This is that thing where you have to assign numbers -- sort of like x-y coordinates except there's four of them -- to each electron in an atom whilst obeying the Pauli Exclusion Principle: the principal quantum number, azimuthal quantum number, magnetic quantum number, and spin.

This video appears on the page: Quantum Numbers

Quantum Numbers

Sort of like the quantum version of x-y coordinates for electrons, these four coordinates give the shell, orbital type, sub-orbital and spin of every electron in an atom (Pauli Exclusion Principle).

Part of the course(s): Physics ,Chemistry-General