Lab Report 14:CHEM 106. Acids and Bases are pHun.

Lab Report 14:CHEM 106. Acids and Bases are pHun. Introduction: Lab Report 14. CHEM 106: Acids and Bases are pHun. One of the ways we categorize solutions in chemistry is by dividing them into two groups; acids and bases. Acids are substances which donate Hydronium (H3O + ) ions in aqueous solution and have a pH under 7. Bases will produce hydroxide (OH- ) ions in aqueous solution and have a pH over 7. When acids and bases of relatively equal strength react with each other they can produce a neutral salt, which has a pH of 7. If acids or bases of differing strengths react, then the resulting salt may be slightly acidic or slightly basic, depending on the strengths of the acids/bases that reacted to form it. Some solutions, like water, have a very fluid pH that can be changed very easily by simply adding strong acids and bases to the solution, which will then dissociate, thus changing the pH of the solution. Other solutions, known as buffers, have a very stable pH that cannot be easily changed. This means that the buffer will, for a time, resist a change in the pH due to the addition of a certain amount of strong acid or strong base. These are the four types of solutions (Acid, Base, Salt, Buffer) that we worked with in this lab. In this lab, we used various methods to try and classify solutions as either acids, bases or salts. In the first part of the lab, we used indicator solutions to try and predict the pH of eight different types of solutions (FeSO4, NH4Cl, Na2HPO4, NaH2PO4, Na3PO4, NaCl, NaF, Na2CO3). We then used the molarity, Ka and the chemical reaction equations to calculate the true pH value, and compared these to the predicted value. In the second part of the lab, we compared two solutions, one being an acetate buffer, and the other being deionized water, to see which one was better at maintaining its pH. To do this, we added HCl and NaOH to each solution bit by bit, and observed how the pH changed as greater volumes of acid/base were added over time. Materials:  Lab Manual  Lab Report  Pen and Pencil  Safety Goggles  Graduated Cylinder  Breakers  (4x6) Well Plate  Pasteur Pipet  Burettes (*2)  pH Paper  0.1M FeSO4  0.1M NH4Cl  0.1 M Na2HPO4  0.1 M NaH2PO4  0.1 M Na3PO4  0.1 M NaCl Lopez 2  0.1 M NaF  0.1 M Na2CO3  0.1 M HCl  0.1 M NaOH  0.1 M Acetic Acid  0.1 M Sodium Acetate  Thymol blue:  Methyl orange  Methyl red  Bromothymol blue  Phenolphthalein  Alizarin yellow Observations: Part 1 (Indicator Solutions and their colors): Initial Colors of Solution and Indicators:  FeSO4: Dark Orange/Rusty color  NH4Cl: Clear  Na2HPO4: Clear  NaH2PO4: Clear  Na3PO4: Clear  NaCl: Clear  NaF: Clear  Na2CO3: Clear  Thymol blue: Dark blue  Methyl orange: Dark Orange  Methyl red: Light Orange  Bromothymol blue: Dark Blue  Phenolphthalein: Transparent  Alizarin yellow: Orange Table 1 (Colors after mixing) 0.1M Solution of Thymol blue Methyl orange Methyl red Bromothymo l Blue phenolphthalei n Alizarin yellow FeSO4 Red with brown percip. Brick red with brown Red with brown percip. Yellow with brown percip. White with brown percip. Brown with brown Lopez 3 percip. percip. NH4Cl Yellow Light orange Apricot liquid Light green liquid Clear liquid Clear Yellow Na2HPO4 Dark blue Liquid Light orange Eggshell colored liquid Light Blue liquid Pink liquid Light, clear yellow NaH2PO4 Yellow liquid Bright orange Pink liquid Yellow liquid Cloudy white Liquid Clear Yellow Na3PO4 Dark blue Liquid Lightorange liquid Whiteyellow liquid Blue liquid Magenta Liquid Peach colored liquid NaCl Dark blue Liquid Lightorange liquid Whiteyellow liquid Teal/Green liquid Clear Liquid Whiteyellow liquid NaF Dark blue Liquid Lightorange liquid Whiteyellow liquid Teal/Green liquid Clear Liquid Whiteyellow liquid Na2CO3 Dark blue Liquid Lightorange liquid Whiteyellow liquid Blue liquid Magenta Liquid Peach liquid ^ Top Half of Table Bottom Half of Table ^ Conclusions based on Indicator Color:  FeSO4: bromothymol blue gave it a yellow-ish color. (pH around 6)  NH4Cl: bromothymol blue gave it a light green color, (pH a bit greater than 6)  Na2HPO4: phenolphthalein gave it a pink color. (pH about 8.5)  NaH2PO4: Methyl red turned it pink and bromothymol turned it yellow. (pH about 5)  Na3PO4: phenolphthalein gave it a magenta color and alizarin turned it peach. (pH about 10.5).