Homework 1_Key BCH2333 Winter 2015 Topics covered: review‚ Chemical Evolution‚ Water‚ Non-covalent bonds‚ Acid/base‚ pH 1. i) Convert using scientific notation to liters: 4 nanoliters‚ 4 x 10-9 L‚ 20 microliters‚ 2x10-5 L‚ 35 milliliters‚ 3.5 x 10-2 L‚ 10 deciliters‚ 1 L‚ 7 kiloliters 7 x 103 L ii) Convert using scientific notation to grams: 6 mg‚ 6 x 10-3 g‚ 21 µg‚ 2.1 x 10-5 g‚ 503 ng‚ 5.03 x 10-7 g‚ 10 kg‚ 1 x 104 g 2. Which of the following properties of water explains its ability to dissolve
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Feb. 19‚ 2015 Liangting Lin 1-4 Lab Partner: Sunny Zhao 20C: Acid-Base Titration Purpose/Objective: 1. To titrate a hydrochloric acid solution of unknown concentration with 0.50M sodium hydroxide‚ and determine the molarity of the hydrochloric acid 2. To titrate an acetic acid solution with 0.50M sodium hydroxide‚ and determine the molarity and percentage composition of the vinegar. Apparatus
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I did this lab to find out the differences between chemical and physical changes. I also did this lab to learn the signs that would indicate the chemical reactions and physical changes. I needed to learn the odor change‚ color change‚ bubbles or gas‚ irreversible‚ temperature changes and finger prints. By the end of the lab‚ my goal was to be able to didtinguish easily the difference between chemical and physical changes. Question #1 answer. 1. Gas. 2. Dissolved in water. 3
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Being able to identify unknowns is important in chemistry because it allows chemists to identify what chemicals they are working with if they have been improperly labeled or if they are trying to determine substances in a compound. Molecular weight and pKa are two properties that help to identify unknown compounds. To find the pKa of an unknown‚ pH meters are used during titrations to measure the potential difference in a solution by measure the difference of hydrogen-ion activity in a solution and
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Figure 1 shows the average amount of absorbance for each tube‚ containing different levels of pH. Tube 2 had an acidic pH level‚ Tube 3 had a neutral pH level‚ and Tube 4 had a basic pH level. It is indicated that the absorbance rates were the highest for the neutral pH level‚ with a final absorbance rate of 0.166. This was followed by a basic pH (0.106). The acidic pH level had the least amount of absorbance with a final absorbance rate of 0.069. This reinforces the idea that the ALP enzyme worked
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Figure 1: Titration curve of 0.160 grams of an unknown diprotic acid that was dissociated in distilled water. Shown is the pH versus the volume in milliliters of 0.1 M NaOH‚ a strong base‚ added to the solution. The initial pH reading of the solution was a pH of 2.60. Although the pH of the ½ equivalence point was unknown‚ it could be estimated by halving the volume of NaOH used at the first equivalence point. At the first equivalence point‚ 13.63 milliliters of NaOH had been added to the unknown
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Research Question: To investigate how varying the pH of bromothymol blue affects the absorbance value of the solution which determines the equilibrium constant (pKa) of the indicator. Variables: Variables Variables Measured Method of measurement Independent pH of the six buffer solution A pH probe attached to a data-logger will be used to measure pH Dependent Absorption of the buffer solutions at wavelength 435.0nm and 617.0 nm A spectrophotometer (±0.001) will be used to measure absorbance
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In this lab‚ we were able to determine measuring the pH of liquids work. We were able to compare the liquids based on their pH level and determine which liquid was acidic or basic. Our results showed that if something came out to be seven or less‚ according to the pH scale‚ it means that an acid is a substance that donates hydrogen ions. Because of this‚ when an acid is dissolved in water‚ the balance between hydrogen ions and hydroxide ions is shifted. Now there are more hydrogen ions than hydroxide
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During the preparation of the 0.100M Tris buffer‚ the calculated amount of ingredients brought the solution to a pH of 7.0‚ but the desired pH was 7.50. Discrepancies between the theoretically calculated amounts and the actual measured amounts of ingredients are likely to be the biggest source of error. Dilution affected our 0.0100M Tris buffer by decreasing its pH. The buffer was originally set to a pH of 7.48‚ but the pH gradually moved down by a pH unit of about 0.1 after each dilution. This is
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Conclusion Both Kool Aid and Gatorade contain buffers. For the buffer in Kool Aid‚ pKa1 ≈ 3.70‚ pKa2 ≈ 4.90‚ pKa3 ≈ 6.50 and for the buffer in Gatorade‚ pKa1 ≈ 4.50‚ pKa2 ≈ 5.40‚ pKa3 ≈ 6.70. Discussion of Theory A buffer capacity is the maximum amount of hyrdrogen or hydroxide ion that can be added to a buffered solution before a significant change in the pH occurs. Increasing the concentration of the buffer can increase the buffer capacity of a solution. At the half equivalence point‚ the moles
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