Caffeine post lab

11.An acid-base equilibrium system is created by dissolving 0.20mol CH3COOH in water and diluting the resulting solution to a volume of 1.0 L. What is the effect of adding 0.020 mol CH3COO (aq) to this solution? How will pH change (calculate pH before and after the addition. Ka of CH3COOH is 1.76 x10-5)? How will concentrations of CH3COOH and CH3COO at equilibrium change?

Disulfides are compounds that have S¬ S bonds, like peroxides have O¬ O bonds. Thiols are organic compounds that have the general formula R¬ SH, where R is a generic hydrocarbon. The SH- ion is the sulfur counterpart of hydroxide, OH-. Two thiols can react to make a disulfide, R¬ S¬ S¬ R. If you wanted to convert a disulfide to two thiols, should you add a reducing agent or oxidizing agent to the solution?

When the reversible reaction HC2H;O2 (aq) E> H(aq) + C2H3O2 (aq) is at equilibrium at room temperature, pH of the reaction mixture is 5. What will be the change in pH when you add a large amount of NaOH (aq) to the reaction mixture? a) pH will not change because NaOH is not a part of the reaction equation. b) pH will not change because acetic acid and NaOH form a buffer. c) pH will increase because NaOH will completely neutralize acetic acid. d) pH will decrease because NaOH will completely neutralize acetic acid. In the reversible reaction A (aq) + B(aq) E > C(aq), reactant A is very expensive. What are two ways to get it to react as fully as possible to form as much C as possible? a) remove C as it forms, and use an excess of A b) add another reactant that will form a precipitate with B c) remove C as it forms, and use an excess of B d) add another reactant that will form a precipitate with A

The preparations of two aqueous solutions are described in the table below. For each solution, write the chemical formulas of the major species present at equilibrium. You can leave out water itself. Write the chemical formulas of the species that will act as acids, the formulas of the species that will act as bases, and the formulas of the species that will act as neither acids nor bases. You will find it useful to keep in mind that NH3 is a weak base. A. 1 mol of HBr is added to 1 L of a 0.8M NH3 solution. B. 0.34 mol of HBr is added to 1 L of a solution that is 1.3 M in both NH3 and NH4Br

The equilibrium expression for any weak acid can be written as HA (aq) + H20 (1) = A- (aq) + H;O+ (aq) 1. Write the K value expression based on the equation above (remember that pure liquids are not included in the K expression). This is given the special symbol Ka. 2. In this experiment, you will be using pH to find [H3O+]. The relationship is [H3O*] = 10-PH . For a pH of 7.4, find the [H3O+].

1,2-Dichloroethane is a volatile organic compound that was once added to gasoline along with the heavy metal lead. At many former gasoline storage sites, the unsaturated soil and groundwater are still contaminated with 1,2-dichloroethane. One of the concerns with volatile organic compounds in the unsaturated zone of soil is that they can diffuse into buildings and contaminate the air. Calculate the concentration of 1,2- dichloroethane in air that will result in a carcinogenic risk of 104, based on a breathing rate of 11.3 m/d, exposure for 10 hours per day, and an inhalation PF of 9.1x102 kg•d/mg. Express your answer in µg/m³. А. Calculate the concentration of 1,2-dichloroethane in groundwater that will result in a hazard quotient of 1, based on drinking 2 L of water per day for a lifetime and an oral RfD of 0.012 mg/(kg d). Express your answer in ppb. В.

An experiment to determine the standard molar enthalpy of neutralization of a strong acid by a strong base is to be performed. Standard laboratory equipment and a supply of standardized 1.00-molar HCl and standardized 1.00-molar NaOH are available. What equipment is necessary for this experiment? What measurements should be recorded? Without performing calculations, describe how the resulting data should be utilized to obtain the standard molar enthalpy of neutralization. When a class of students performed this experiment, the average of their results was –55.0 kJ/mol. The accepted value for the standard molar enthalpy of neutralization of a strong acid by a strong base is –57.7 kJ/mol. Propose two likely sources of experimental error that could account for the result obtained by the class.

You have a 18 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 8.35. You incubate this sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid dissociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has decreased to 6.03. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in the original 18 mL sample.

Please help answer these questions, I'm stuck on them

You have a 16 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 7.66. You incubate this sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid dissociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has decreased to 5.52. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in the original 16 mL sample. Acetylcholine CH₂ acetycholine in original sample: CH,—C−O−CH,—CH,AN-CH, HO–CH,—CH,*N–CH, + CHy H₂O I CH3 CH3 Choline CH₂ CH,-GO + H Acetate nmol

DETERMINATION OF TOTAL AMOUNT OF ACID IN WINE C4H6O6 + 2 NaOH → (C4H4O6) Na2 + 2 H2O A sample of 10 mL of wine was taken and the volume was completed to 50 mL by adding pure water. This solution was titrated with 0.1 M NaOH and 24 mL of NaOH was spent. According to this Calculate the amount of tartaric acid in wine as g / L.

The following 4 questions involve the titration of a 100.00 mL sample of 0.500 M methylamine, CH3NH2, with 1.00 M HCl (aq., 25 oC). The Kb CH3NH2 = 4.40 x 10–4 1. Calculate the pH of the solution before any HCl has been added. 2. Calculate the pH of the solution after 25.00 mL of HCl has been added. 3) Calculate the pH of the solution after 50.00 mL HCl has been added.

Mola and Rity were tasked to analyze the acidity of a 10.0-mL fermented milk sample diluted with water in a 250-mL volumetric flask. Mola obtained a 15.0-mL aliquot of this solution, diluted it to 50.0 mL, and then titrated this diluted sample. Titration data were given to Rity and she found out that the 50.0-mL diluted sample contains 0.21 mmol of lactic acid. What is the lactic acid concentration (in M) of the titrated sample?

Mola and Rity were tasked to analyze the acidity of a 10.0-mL fermented milk sample diluted with water in a 250-mL volumetric flask. Mola obtained a 15.0-mL aliquot of this solution, diluted it to 50.0 mL, and then titrated this diluted sample. Titration data were given to Rity and she found out that the 50.0-mL diluted sample contains 0.21 mmol of lactic acid. MW: Lactic Acid (90.08) a. What is the lactic acid concentration (in M) of the titrated sample? b. Determine the lactic acid content (in M) of the 10.0-mL fermented milk sample. c. What is the lactic acid concentration (in %w/v) of the 10.0-mL fermented milk sample?

You have a 12 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 8.14. You incubate this sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid dissociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has decreased to 6.55. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in the original 12 mL sample. Acetycholine in original sample:________ nmol

Calculate the concentration of an aqueous solution of Ca(OH)2Ca(OH)2 that has a pHpH of 11.52. Express your answer using two significant figures.

The acid dissociation constant K of hydrocyanic acid (HCN) is 6.2 × 10 10 Calculate the pH of a 3.0M solution of hydrocyanic acid. Round your answer to 1 decimal place. pH = 0

Once upon a time, Tricia and her sister Jillian are doing titration to assess the molarity of the sample's total acid content. Using the pH measurements to report acidity, they were ordered to study a clear aqueous solution of an unknown monoprotic acid.They decided to use two methods of experiments to gather essential data for their Chemistry Class.The first method is through a pH strip. To estimate the pH of the sample, Tricia used a pH strip. Tricia collected 1 mL of the sample, which came out to have a pH of around 3.3. Furthermore, Tricia made a new setup in which 1 mL of the same sample was diluted with 9 mL of water, and the pH taken was now around 3.8.The second method is Titration, and Jillian used this method. Jillian prepared a 10 mL aliquot of the sample and diluted it with 25mL of distilled water. After this, Jillian added 2 drops of phenolphthalein, and it was titrated 3.54 mL of 0.048 mmol standardized NaOH to the endpoint.1. Determine of the unknown is a strong acid a…

Once upon a time, Tricia and her sister Jillian are doing titration to assess the molarity of the sample's total acid content. Using the pH measurements to report acidity, they were ordered to study a clear aqueous solution of an unknown monoprotic acid. They decided to use two methods of experiments to gather essential data for their Chemistry Class. The first method is through a pH strip. To estimate the pH of the sample, Tricia used a pH strip. Tricia collected 1 mL of the sample, which came out to have a pH of around 3.3. Furthermore, Tricia made a new setup in which 1 mL of the same sample was diluted with 9 mL of water, and the pH taken was now around 3.8. The second method is Titration, and Jillian used this method. Jillian prepared a 10 mL aliquot of the sample and diluted it with 25mL of distilled water. After this, Jillian added 2 drops of phenolphthalein, and it was titrated 3.54 mL of 0.048 mmol standardized NaOH to the endpoint. With this, answer the following questions.1.…

Once upon a time, Tricia and her sister Jillian are doing titration to assess the molarity of the sample's total acid content. Using the pH measurements to report acidity, they were ordered to study a clear aqueous solution of an unknown monoprotic acid.They decided to use two methods of experiments to gather essential data for their Chemistry Class.The first method is through a pH strip. To estimate the pH of the sample, Tricia used a pH strip. Tricia collected 1 mL of the sample, which came out to have a pH of around 3.3. Furthermore, Tricia made a new setup in which 1 mL of the same sample was diluted with 9 mL of water, and the pH taken was now around 3.8.The second method is Titration, and Jillian used this method. Jillian prepared a 10 mL aliquot of the sample and diluted it with 25mL of distilled water. After this, Jillian added 2 drops of phenolphthalein, and it was titrated 3.54 mL of 0.048 mmol standardized NaOH to the endpoint.1. Using the data in the titration method,…

You have a 20 mL sample of acetylcholine (a neurotransmitter) with an unknown concentration and a pH of 8.17. You incubate this sample with the enzyme acetylcholinesterase to convert all of the acetylcholine to choline and acetic acid. The acetic acid dissociates to yield acetate and hydrogen ions. At the end of the incubation period, you measure the pH again and find that it has decreased to 6.70. Assuming there was no buffer in the assay mixture, determine the number of nanomoles of acetylcholine in the original 20 mL sample. -Å-—•- CH,—C−O−CH,—CH,—*N–CH, Acetylcholine CH₂ acetycholine in original sample: CH₂ H₂O CH₂ I HO–CH,—CH,—*N–CH, + CH Choline CH₂ CHO Acetate H* nmol

You are studying a clear solution and you added the pH indicator methyl violet. The colour range of the indicator methyl violet in a clear solution when changing from acidic to basic is yellow (pH 0) to blue purple (pH 1) to violet (pH 2). You initial pH of the solution when tested with a pH meter is O.2. You are going to add 250 drops of 0.1 M HCI. Please select the most appropriate answers to the following two questions. What is the initial colour of the solution at pH 0.2? What is the colour of the solution and what will the pH be after the addition of the HCI? Select 2 correct answer(s) The colour of the solution after the addition of HCI will be clear and the pH will be less than 0.2. The colour of the solution after the addition of HCI will be violet and the pH will be higher than 0.2.

A Dashboard 101 Chem101 + а ap.101edu.co Question 10 of 16 Submit Complete the balanced chemical reaction for the following weak base with a strong acid. In this case, write the resulting acid and base as its own species in the reaction. NH:(aq) + HCI(aq) - 14- O3- |2+ 3+ 14+ 1 2 3 4 7 9. 1 I5 16 (s) (g) (aq) H3O+ H2O OH- CI Reset • x H2O Delete + 10:24 PM P Type here to search 65°F Mostly sunny 10/31/2021 1L

An acid-base equilibrium system is created by dissolving 0.50 mol CH3CO2H in water to a volume of 1.0 L. What is the effect of adding 0.50 mol CH3CO2–(aq) to this solution? 1.The pH of the solution will equal 7.00 because equal concentrations of a weak acid and its conjugate base are present. 2.Some CH3CO2H(aq) will ionize, increasing the concentration of CH3CO2–(aq) and increasing the pH.3.Some CH3CO2–(aq) will react with H3O+, increasing the concentration of CH3CO2H(aq) and reestablishing the solution equilibrium. b. 2 only c. 3 only d. 1 and 3 e. 1, 2, and 3

In the laboratory, a general chemistry student measured the pH of a 0.527 M aqueous solution of methylamine, CH3NH₂ to be 12.159. Use the information she obtained to determine the Kb for this base. Kb (experiment) = Show Transcribed Text In the laboratory, a general chemistry student measured the pH of a 0.524 M aqueous solution of pyridine, C,HSN to be 9.461. Use the information she obtained to determine the K, for this base. Kb (experiment) =

2

Consider the following chemical equilibrium: HCOO¯¯ (aq) + H₂O(aq) = HCOOH(aq) + OH¯(aq). Which of the following graphs represents the perturbation on the system and the change of pH when HCI is added to the container? | pH time || III pH ↑ time Select an answer and submit. For keyboard navigation, use the up/down arrow keys to select an answer. C Q a || = III = d IV pH IV pH time time K Open Χ Your answer

In Experiment 4, we used titration to determine the total acid content of samples, which we reported in terms of molarity. Reporting acidity through pH measurements is quite different, in that we can only measure the amount of the acid in its ionized form. You were tasked to investigate a clear aqueous solution of an unknown monoprotic acid. You decided to use two Chem 16.1 methods to gather data.Method 1 – TITRATION: A 10. mL aliquot of the sample was diluted with 25 mL distilled water. Two drops of phenolphthalein were added and then it was titrated 3.54 mL of 0.048 M standardized NaOH to the endpoint.Method 2 – pH STRIP: You took 1 mL of the sample and used a pH strip to estimate the pH, which turned out to be around 3.3. Another 1 mL of the sample was diluted with 9 mL of water. The pH was taken again and is now around 3.8 d) Based on your answer in a) and c), do you think the unknown is really a strong acid or is it a weak acid instead? Defend your answer in one sentence.e)…

In Experiment 4, we used titration to determine the total acid content of samples, which we reported in terms of molarity. Reporting acidity through pH measurements is quite different, in that we can only measure the amount of the acid in its ionized form. You were tasked to investigate a clear aqueous solution of an unknown monoprotic acid. You decided to use two Chem 16.1 methods to gather data.Method 1 – TITRATION: A 10. mL aliquot of the sample was diluted with 25 mL distilled water. Two drops of phenolphthalein were added and then it was titrated 3.54 mL of 0.048 M standardized NaOH to the endpoint.Method 2 – pH STRIP: You took 1 mL of the sample and used a pH strip to estimate the pH, which turned out to be around 3.3. Another 1 mL of the sample was diluted with 9 mL of water. The pH was taken again and is now around 3.8 a) Calculate the molarity of the acid using the titration data.b) If we assume that the titrated unknown is a strong acid, predict the pH of the sample.c) Using…