# Pretty Colors Lab

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Pretty Colors Lab Background: In the pretty color lab I will be showing the effects of diluting a strong acid and strong alkali on the pH. The pH scale measures how acidic or basic a substance is, indicated by what is called an indicator. The pH scale varies from 0 to 14, below 7 being acidic, above 7 being basic, and 7 being neutral. There will be three different indicators used in the lab, Phenolphthalein, Universal, and Cabbage juice. Each of these indicators will be used to show the various colors created when diluting the acids and bases. When measuring the dilutions 1.0 M HCl can be serially diluted from pH < 1 until its pH reaches 7.0 and 1.0 M NaOH can also be diluted from pH > 14 until it reaches 7.0. In the middle well there is just purely water because it is the most neutral substance, neither acidic nor basic. Water has Hydrogen and hydroxide ions, which helps determine if the substance is an acid or base. The acids are determined on how much H they have and bases are determined on how much they mess with the hydrogen concentration. When looking at the acid and base used in this lab HCl is an acid and NaOH is a base. To determine a pH value the molarity of the acids and bases must be below one, so using .1 M NaOH and HCl is ideal. To measure the pH the mathematical equation is used: pH = -log [H+] and pOH = -log [OH-]. When adding these up the end result has to be 14 because acids go from 1-7 and basic from 14-7. Basically when adding base to water solutions the hydrogen’s will get stolen, decreasing the amount of available hydrogen ions, and increase the pH beyond 7. This is important because the Keq is somewhat affected as well. Materials: - .1 M NaOH - .1 M HCl - Pipette - Wells - Beaker - Phenolphthalein - Universal - Cabbage juice - Safety goggles Procedure: 1. Gather all materials and put on goggles. 2. In the first