Aim: | The aim of this experiment is to analyse a sample of vinegar and determine it’s concentration. | | | Hypothesis: | It’s expected that the aceatic acid will have the concentration of 0.1mol as this is the molarity of the NaOH as they have a 1:1 ratio of moles as it states in their chemical equations. | | | Apparatus: | * 1 x retort stand * 1 x retort burette clamp * 1 x burette * 1 x pipette * 1 x glass funnel * 2 x Conical Flasks * Sheet of filter paper * 200mL of 0.1 mol L-1 NaOH * 200mL of acetic acid of unknown concentration | | | Procedure: | 1. WARNING: Wear safety glasses and gloves! 2.
Intro to Biology Bio 101-51 3/25/2014 Abstract: The pH levels of four different types of shampoos were tested to compare them to the pH range (4.5-5.5) of untreated hair. The pH levels of three shampoos commonly found in salons were tested, while the pH of one generic shampoo was tested. The effects of human hair and using shampoo that is highly alkali or acidic are discussed. Introduction: This experiment tested the pH levels of four different shampoos. The shampoos’ pH levels were compared to the range of pH levels found in untreated hair.
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.
Chemistry 75a | Experiment1: Solubility | George Sayegh | | Dr. Tjandra | 9/3/2013 | | Purpose: To be able to gain a good understanding in solubility behaviors through polarity and Acid-Base techniques. In the experiment we will gain an understanding of the structural futures of a substance that determines its solubility in various solvents. Experimental and Data/Result: Part A: Solubility of Solid Compounds: In this Part A of the experiment we will test the solubility of 3 organic compounds, Benzophenone, Succinic Acid, and Biphenyl in the same method for all three. To each organic compound we will add water (highly polar), Methyl Alcohol (intermediate polar), and Hexane (non-polar). Using these 3 testers we will see the solubility of each organic compound and also how it relates to the
Most differential stains have a challenge step that follows staining with a primary dye. In the Gram stain the challenge step is a rinse with either ethanol or acetone (either may be used). This step dehydrates and tightens the cell wall of Gram positives (mainly peptidoglycan) such that the rinse does not enter the cell. Gram negatives have mainly a lipid cell wall (even though they do contain peptidoglycan) that allows the challenge rinse to penetrate the cell and rinse out the crystal violet-iodine complex rendering the Gram negative cell colourless. Thus, the Gram negative cells must be stained to be seen, and this is done with the counter stain.
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.
Reactivity: Caustic on organic matter Electric conductivity: Aqueous solutions or molten bases dissociate in ions and conduct electricity Common Bases Ammonia base is a weak base and can be found in window and floor cleaners. Brief Explanation of Experiment We have tested household substances to determine their pH level and description of pH(strong/weak, acid/base or neutral) Indicator An indicator is a substance that determines whether a substance is an acid/base/neutral. It changes the colour of the substance depending on how much water the substance contains. The pH measures the acidity in a solution. Prediction: Water: 7.0, Green, neutral.
At this point the volume of base used to neutralized the acid can be determined. Phenolphthalein is the indicator which is colorless in an acid but changes to a faint and permanent pink color in base. The purpose of this experiment is to prepare a sample for titration with a base, become familiar with a buret while using proper titration technique in reaching an end point. Hypothesis : If I titrate a base of known concentration with an acid of unknown concentration then I can determine the concentration can be calculated because of the titration calculation. Materials : • Vinegar • Two small beakers (150mL) • 250-mL Erlenmeyer flask • 10-mL graduated cylinder • 50-mL buret • Buret clamp • Small funnel • M NaOH Hazards : • Chemical spill • Broken glass
Indicator | Initial Volume of NaOH solution (ml) ±0.05 | Final Volume of NaOH solution (ml) ±0.05 | Difference Between the Final and Initial Burette Readings (Volume of NaOH used) (ml) ±0.1 | Qualitative Observations | Phenolphthalein | 0.0 0 | 0.90 | 0.9 | The indicator is clear and transparent at first. However, when the base is added and the endpoint has been reached, the color changes to a light pink. If over titration occurs, the solution will be a fluorescent pink color. | | 0.90 | 2.30 | 1.4 | | | 2.30 | 3.20 | 0.9 | | | 3.20 | 4.10 | 0.9 | | Bromothymol Blue | 8.00 | 9.50 | 1.5 | The indicator is yellow at first. However, when the base is added and the endpoint has been reached, the color changes to olive green.
Hydrogen chloride (HCl acid) and sodium hydroxide (NaOH base) – sodium chloride and water Beryllium hydroxide ( Be(OH)2 not to acids ) One of the first things that you will learn in your high school or college chemistry class is that an acid always neutralizes a base, and a base always neutralizes an acid. Acids include vinegar, muriatic and citric fruits like lemons, and will turn a litmus paper red. Bases include sodium hydroxide, calcium hydroxide, ammonia water and many bleaches, and will turn litmus paper blue. Although neutralizing acids and bases is simple in theory, you have to be extremely careful when working with chemicals in order to prevent serious burns NaOH (sodium hydroxide) HCl + NaOH --> NaCl + H2O NaCl is table salt which is neutral A salt is any compound which can be derived from the neutralization of an acid and a base. The word "neutralization" is used because the acid and base properties of H+ and OH- are destroyed or neutralized.