9-16-13

This week, we learned about stoichiometry and the relationship between concentration of a solution and transmittance of light. Stoichiometry is the mass and amount relationships between reactants and products in a chemical reaction. In simpler terms, it refers to the relative proportion of components. It's also important for equations to be balanced. The molecules on one side of an equation must be equal to the molecules on the other side, and the masses (in both amu and grams), and the amount of moles on one side must add up to the mass on the other side of the equation. Mole ratios are the ratio of the coefficient of one molecule or formula unit in a balanced chemical equation to the coefficient of another one in the equation. I learned that in an equation such as, 4NH3(g) + 5O2(g) → 4NO(g) + 6H2O(g)  the mole ratio of ammonia (NH3) to oxygen is 4:5. All stoichiometric equations must have a mole ratio, otherwise they can't be completed. You can also use equations to find the amount of moles needed in a reaction. (http://www.esf.edu/efb/schulz/Stoichiometry.htm)

In class, we also did an experiment that helped show the relationship between the concentration of a solution and the amount of transmitted light that will pass through. We used blue #1 dye to make each solution. Each solution contained a certain amount of mL of the dye, and a certain amount of mL of deionized water. We also tested Powerade and Gatorade. From this experiment, I learned that the higher the concentration of the solution, the lower the amount of transmitted light. From this I learned that concentration and transmitted light are inversely related, and concentration and absorption are directly related. We used a colorimeter to get these results.

I understand the ideas we learned in class this week, especially from the lectures and the worksheets. With a little more practice on setting up the equations like those on the stoichiometry worksheets, I think I'll fully understand it.