Brad Hopkins CHM 145 A Shadi Abu-Baker Cheng Guo Alex Hudson 10/10/2011 Experiment #4: Ionization Constants of Weak Acids Qualitative Data: The indicator dye that we used was Blue (1). During the qualitative analysis I was able to use the shades of the buffer solutions after the dye was added to determine an estimate of the pKa of the dye. This is because according to the Henderson-Hasselbalch equation, the pH = pKa when there are equal amounts of the forms of due present. To determine when the amounts were equal, observations were made on the dye coloration. When the KH2PO4 was of a greater volume the resulting dye was yellow in color; when the K2HPO4 was in greater volume the resulting dye color was dark blue in color.
| Summary: Alcohols________________ | Water (highly Polar)_____ | Hexane (Non-Polar)______ | 1-OctanolCH3(CH2)6CH20H | Insoluble | Soluble | 1-ButanolCH3CH2CH2CH2OH | Partially soluble | Soluble | Methyl AlcoholCH3OH | Soluble | Insoluble | Part C: Miscible or Immiscible Pairs: In the experiment Part C we will obtain five test tubes total, four filled with water and the last test tube with Hexane. With the five test tubes we will be mixing other liquids in each individual test tube to see if the solution is miscible or immiscible. Note to take, like mixes with like. Procedure | Observation | TT1: 1ml water + 1ml Ethyl Alcohol | Miscible | TT2: 1ml water + 1ml Diethyl Ether | Immiscible | TT3: 1ml water + 1ml Methylene Chloride | Immiscible | TT4: 1ml water + 1ml Hexane | Immiscible | TT4: 1ml Hexane + 1ml Methylene Chloride | Miscible | Part D: Solubility of Organic Acids and
For reasons that are beyond the scope of the material covered so far (but which will be covered in CHE 132), the solution is very slightly basic at the end point of a weak acid-strong base titration. Consequently, an indicator must be chosen which changes color when the solution changes from acidic to basic. Either phenolphthalein (colorless in acid, red in base, also used as the active ingredient in Ex-Lax) or thymol blue (yellow in acid, blue in base) may be used. Both indicators change color when the solution becomes very slightly basic Equipment: 25-mL pipette, 50-mL burette, 100-mL graduated cylinder, three 250-mL Erlenmeyer flasks, three 150-mL or 250-mL beakers, burette funnel, 250-mL volumetric flask, wash bottle, pipette bulb, eyedropper or Pasteur pipette with bulb, burette stand. You will be working by yourself.
Experiment 9 - Effects on Vitamin C (with PH) Research Question: How does the change of PH (increase of decrease) effect the amount of vitamin C in a vitamin C solution? Goal of Experiment: Have the opportunity to independently design and perform a scientific study on an aspect of vitamin C decomposition. Hypothesis: I predict that by introducing HCl or NaOH into the vitamin C solution the percentage of vitamin C present in the solution will decrease. Abstract: The purpose of this lab is to determine the effects that changing the PH of a vitamin C solution will have on the concentration of vitamin C. The concentration changes will be calculated after 6 titrations (2 control, 2 with added NaOH, and 2 with added HCl) . Once calculated, these results can be analyzed and will either validate or refute my hypothesis.
A pH indicator is a halochromic chemical compound that is added in small amounts to a solution so that the pH (acidity or basicity) of the solution can be determined visually. Hence a pH indicator is a chemical detector for hydronium ions (H3O+) or hydrogen ions (H+) in the Arrhenius model. Normally, the indicator causes the color of the solution to change depending on the pH. At 25° Celsius, considered the standard temperature, the pH value of a neutral solution is 7.0. Solutions with a pH value below 7.0 are considered acidic, whereas solutions with pH value above 7.0 are basic.
Title : Reaction of Carboxylic Acids Objective : To Determine The Reaction of Carboxylic Acids Procedure : As referred to Lab manual. Results: A. Salt Formation |Compound |Solvent |Solubility | |Benzoic Acid |Cold Water |Partially soluble | |Benzoic Acid |10 % NaOH |Soluble | B. Salt Hydrolysis Sodium acetate solution changed the color of litmus from red to blue. C. Reaction With Sodium Carbonate Observation : A lot of gas bubbles was released.
Background: For the entire explanation of this demo see Shakhashiri's Chemical Demonstrations, Vol. 4, pp 42-43. The following is a excerpt from this volume. " The sudden change from colorless to deep blue solutions in this demonstration can be explained with the following sequence of equations[2]: 3 I-(aq) + H202 + 2 H+ (aq) = I3- (aq) + 2 H20 (l) (1) I3- (aq) + 2 S2O3 2- (aq) = 3 I- (aq) + S4O6 2- (aq) (2) 2 I3- (aq) + starch = starch-I5- complex + I- (aq) (3) The first equation indicates that, in an
Method: In this investigation same volume of 3 different types of orange juice are used, to find out which one has the most Vitamin C. This investigation involves using the organic indicator called Dichlorophenolindophenol which abbreviates to DCPIP. The indicator is a dark blue colour which turns colourless when a known amount of it is used neutralize ascorbic acid which is Vitamin C. The amount of juices used to turn the DCPIP colourless will be recorded and the vitamin C content will be determined by measuring the amount of a known vitamin C concentration
This was not a hard lab, but had a lot of new informations involved in it. I learned how to do the quantitative analysis between aldehydes and ketones. Introduction The Laboratory experiment focus on finding the unknown chemical based on those different tests which can eliminate the wrong guess. Both aldehydes and ketones have the carbonyl group, and the two carbon atoms of ketones only bond to carbonyl carbon without the hydrogen, but in the case of aldehydes one of the hydrogen has to bond with the carbonyl carbon. So, those carbonyl group could be aliphatic or part of the aromatic ring because they share carbonyl group.
Exp 3 The purpose of this experiment is to determine the reaction that happens to the calcium carbonate when it is added to HCl acid. Exp 4 The purpose of this experiment is to test 2-3 different indicators in acidic and alkali solution. Exp 5 The purpose of this experiment is to test the pH value of random substances and determine whether they are acidic or alkali. Materials used: Equipments and materials 1) Universal indicator 2) 2 mole/dm3 of Hydrochloric acid (HCl) 3) 2 mole/dm3 of sodium hydrochloric(NaOH) 4) Test tube 5) Magnesium ribbon (Mg) 6) Calcium Carbonate in the form of limestone or marble (CaCO3) 7) 2-3 indicators (bromothyle, litmus and sulfone phthalein) 8) Test tube rack 9) Glass stirring rod 10) Beaker 11) Pipettes 12) Demineralized water 13) Random substances (baking soda, pineapple, pear, orange, sugar etc ) Theory Acids are chemical substances, which have a sour taste. There are two types of acids, weak acids and strong acids.