There are many things I learned in Module 7. Some of them where: what is the difference between an acid and a base; what is pH; what is equilibrium, what is Le Châtelier's principle; and what is oxidation. Here are some of the things I learned in lesson 07.01 (Acids and bases) and lesson 07.02 (Acid-base reactions). An acid is a substance that produces hydrogen ions, H+, or hydrodium H3O+ ions in solution. There are three “types of acids”: Arrhenius, BrØnsted-Lowry and Lewis Acid. An Arrhenius acid is a substance that increases the concentration of hydrogen ions, H+ or hydronium ions H3O+ when dissolved in water. You have to have water. A BrØnsted-Lowry acid is any substance that donates a hydrogen ion, H+, to another substance. A Lewis acid is any substance that accepts a lone pair of electrons. A strong acid is one that breaks down almost 100% when in solution (example HCl). When dissolved in water, HCl breaks down into H+ and Cl- ions. Not all acids break down. A weak acid is/are chemicals that do not break down well. Acids have a sour taste, are: corrosive and electrolytes. Acids react with active metals (group 1 or 2) to produce hydrogen gas, H2. They also react with bases to produce salt and water (a neutralization reaction). An Arrhenius base is any substance that increases the concentration of hydroxide ions (OH-) when dissolved in water. A BrØnsted-Lowry base is a base that accepts a hydrogen ion, H+. A Lewis base is any substance that donates a lone pair of electrons. Bases taste bitter, bases react with acids to produce a neutralization reaction, and basic solutions feel slippery. On the pH scale, 7 is neutral. An acidic solution will have a higher concentration of hydrogen ions than hydroxide ions... in the center of the paper... the reaction to move to the right would be to remove the products. A third way is to change the temperature. Since it is an endothermic reaction, +∆H, we can imagine that the "heat" is a reactant. Therefore, if we add heat, it will move to the right. To be classified as a redox reaction, we need at least two elements to change the oxidation state. The easiest way to look at a reaction and determine this is if you have an element alone on one side of the reaction and it is in a compound on the other side. In most cases, the oxidation number of each element in a compound is their common charge. The sum of the oxidation numbers must equal the overall charge of the compound. Elements in their natural state (alone) have an oxidation number of 0. The reducing agent is the species responsible for reducing the other chemical. Therefore, the reducing agent itself is oxidized.