the sample in 38 mL of hydrochloric acid and heating the solution to boiling point. Upon reaching just below boiling point‚ decolorizing carbon was added to the solution‚ and the solution was allowed cooled for 2-3 minutes. The dark black solution was filtered through a gravity filtration system‚ leaving dark residue behind on the filter paper‚ and colorless to slightly pink liquid in the beaker. Then‚ 9 mL of sodium acetate buffer‚ to maintain a relatively constant pH and 1.8 mL of acetic anhydride
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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 ions in the solution (2). A base can increase the pH level by providing hydroxide and then being removed. The buffer section of this lab was used to stabilize the level of pH using 4 different types of samples. The pH levels of the
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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 and Materials: Please refer to P.236 of Health Chemistry Laboratory Experiments. Procedure: Part I Determination of molarity of Hydrochloric Acid Solution
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Increasing the concentration of the buffer can increase the buffer capacity of a solution. At the half equivalence point‚ the moles of base added to the acid is equivalent to half the moles of acid originally present. Thus‚ the amount of the weak acid and its conjugate base are equal. According to the Henderson-Hasselbach equation‚ when [Conjugate Base]/[Acid] is equal to 1‚ then
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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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Lab on pH Levels Purpose: Throughout this experiment we are trying to learn how to take proper pH measurements using a pH meter. We also want to see the pH of different common liquids and record the change in pH when we add acids and alkaline liquids. The last reason we are conducting this experiment is to explain and show how fresh milk spoils by the change in pH. Materials: In this experiment we used graduated cylinders and glass beakers and added variety of ingredients including 50 mL of; soda
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Chemistry 521 Exam I‚ Spring Quarter 7:30 - 9:00 PM‚ 25 April 2000 NAME 1. [10 points] What are the concentrations of HSO− ‚ SO2− ‚ and H+ in a 0.20 M KHSO4 solution? (Hint: 4 4 H2 SO4 is a strong acid; Ka = 1.3 × 10−2 for HSO− .) 4 2. [15 points] Calculate the pH of 1.00 L of the buffer 1.00 M CH3 COONa/1.00 M CH3 COOH (pKa = 4.74) before and after the addition of (a) 0.080 moles NaOH and (b) 0.12 moles HCl. (Assume there is no change in volume). 3. [10 points] The following reaction
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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 acid solution. Once divided by two
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2. The average pH change for the 30 drops of HCl added to the biological material is 4.3. 3. The average pH change for the 30 drops of NaOH added to the biological material is 8.3. 4. (Q2/Q3) compare to the changes in tap water with both the acid and base because its like putting 30 drops in water the first time when you actually put in just 5 drops. The pH changes drastically. 5. The biological materials respond to changes in pH by getting weaker and weaker at a steady pace. 6. The buffer
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Jillian Mulrooney & Emma Zika Test Questions Concept 1: Write the name of the acids and bases from given formula Q-1-1: Name the following base: NaOH Q-1-2: Name the following acid: HCN Concept 2: Write the formula form given name of acids and bases Q-2-1: Write the formula for the following acid: lithium hydroxide Q-2-2: Write the name for the following base: hydrobromic acid Concept 3: Distinguish between acid‚ base‚ neutral compounds based on their properties which can be tested in a lab
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