6AL Lab 5 Worksheet

Acetic acid, HC2H3O2 (aq), was used to make the buffers in this experiment. Write the ionization equation for this weak acid

Assess the suitability of methyl orange to signal the equivalence point in weak acid and strong base of the experiment. Use the pH range over which the methyl orange changed colors to make this determination. If you conclude that methyl orange would not reliably indicate the equivalence point in this reaction, then suggest an alternative indicator which would be more appropriate.

Complete the flow chart below to describe the separation of an acid and base mixture by providing the necessary chemical structures.

The NaOH titrant in this experiment was prepared to be approximately 0.1 M and then was standardized to determine its exact concentration. What possible reasons could there be for not simply weighing the solid NaOH, dissolving to a known volume and calculating its molarity?

The substance to be analyzed – is white, highly soluble in water salt. Addition of diluted sulfuric acid, or hydrochloric acid, or NaOH, or barium chloride, or silver nitrate doesn't produce any precipitates. Interaction with Nessler's reagent leads to formation of reddish-brown precipitate. Addition of antipyrin in acid medium changes color to red. What kind of substance is this? NH,NO3 KNO3 NaCl NH,CH;COO

Before running a titration, you calculate the expected endpoint. However, when performing the experiment, you pass the expected endpoint with no visible color change. What is the most likely problem with the titration set-up? Select one: There was an air bubble in the buret tip. The buret tip is leaking titrant into the analyte. There is not enough indicator in the analyte. The analyte solution is being stirred too quickly.

Use the data below to determine what cations are present in your unknown sample.  You should use both the procedure and the flow chart to make your determinations.   Cation lab data Upon adding NaOH the red litmus paper remains red. Upon adding HCl no precipitate is formed Now you add NaOH to your sample followed by hydrogen peroxide and a precipitate forms.  You separate this into precipitate 5 and solution 5 To the above precipitate(5) you add HCl and hydrogen peroxide and notice the precipitate has disappeared.  You then add ammonia and a precipitate forms.  You separate the precipitate by centrifugation into precipitate 7 and solution 7.  You then test the precipitate by adding HCl which solublilizies the precipitate, you then add ammonia and a precipitate forms.  Upon addition of KSCN a blood red precipitate is formed. To solution 7 you add potassium acetate and acetic acid.  You separate the resulting solution into 2 parts.  To the first part you add potassium nitrite and a…

Volumetric Analysis  The mass of KHC8H4O4 is measured to the nearest milligram; however, the volume of water in which it is dissolved is never of concern—water is even added to the wall of the Erlenmeyer flask during the titration. Explain why water added to the KHC8H4O4 has no effect on the data, whereas water added to the NaOH solution, may drastically affect the data.

The substance to be analyzed – is white, highly soluble in water salt. When interacting with concentrated sulfuric acid - evolving of some odorless and colorless gas is observed. Reaction with diluted acids or NaOH solution doesn't lead to any precipitation. Interaction with Nessler's reagent leads to formation of reddish-brown precipitate. Addition of barium chloride solution leads to appearance of white precipitate, which soluble in acetic acid. What kind of salt is this? (NH,),CO3 K2CO3 ZNSO3 Na,C204

What factor affects the ‘strength’ of a buffer? Why was benzoic acid used as a solvent when making up the glucose stock standard solution?

In a similar experiment to the one you have performed a student is measuring the equilibrium for an organic acid that is soluble in water and in cyclohexane, a nonpolar organic solvent. When shaken with the solution of water and cyclohexane, it distributes between the organic and aqueous phase. The two phases are separated and titrated with 0.120 M NaOH. Calculate the equilibrium constant for an acid where the titration of the aqueous phase requires 9.92 mL of the base and the organic phase requires 1.51 mL of the base.

Would appreciate help in explaining and showing how to calculate these questions, especially with the different mL concentrations. Thank you.

Which qualitative test for the identification of an anion was most interesting? Briefly justify your answer

1,4‐Dimethoxybenzene (0.642 g) was dissolved in 2.0 mL acetic acid in a 25 mL Erlenmeyer flask using heat from a hot plate. Once the solid dissolved, 1.0 mL tert‐ butanol was added, and the reaction mixture was cooled in an ice bath. Then 2.0 mL concentrated sulfuric acid was added in 2‐3 drop portions,stirring the mixture after each aliquot. After the addition, the flask was removed from the ice bath and allowed to sit at room temperature for 15 minutes. Then 1.0 mL water was added dropwise to dilute the acid and the reaction mixture was added to 40 mL cold water in a 100 mL beaker. The solid was vacuum filtered and washed with 5 mL cold water, giving 52 g filtrate. The product wasrecrystallized from 4.5 mL methanol, yielding 0.317 g purified 1,4‐di‐tert‐butyl‐2,5‐dimethoxy benzene (27.2% yield). What is the atom economy,  e-factor, and effective mass yield?

Suppose your colleague was relying on receiving your purified product in order to prepare a dilute aqueous standard solution of benzoic acid e.g. for a titration. She takes 160 mg of your benzoic acid and dissolves it in just enough water so the solution exactly fills a 250 mL volumetric flask. Given that the acid dissociation constant of benzoic acid Ka = 6.3 x 10-5, calculate the pH of her resulting solution.

25.0 cm3 of sodium hydroxide solution is tritrated against 0.2 mol dm–3 hydrochloric acid until the indicator just changes colour. 27.5 cm3 of the acid are required to reach the end point.Phenolphthalein is used as an indicator in the above experiment. What will be its colour change at the end point?   From pink to yellow From pink to colourless From yellow to colourless From yellow to pink

1. a. Calculate the solubility (S) of lead (II) carbonate, PbCO3 (Ksp = 1.5 x 10-¹³) in water, ignoring other equilibria. Show your work. b. Recalculate the solubility for PbCO3 given that most of the carbonate ion produced subsequently reacts with water to form bicarbonate (and hydroxide). Does the solubility of PbCO3 increase or decrease? Show your work.

1) The question screenshot has been attached down below.

A mixture of the two compounds shown below is dissolved in ether. Using the information given in the experiment, select all the correct statements regarding the extraction and isolation of the two compounds. oja OH X Y QA. Y can be extracted from the organic layer using sodium hydroxide. OB. X can precipitate out of the aqueous layer by the addition of sodium hydroxide to the salt of X. OC. X can be extracted from the organic layer using sodium hydroxide. OD. Y can precipitate out of the aqueous layer by the addition of sodium hydroxide to the salt of Y.

Standard solution : 0.201 grams of acetylsalicylic acid was combined with 10 mL of 0.5 M NaOH, then transfered to a 100 mL flask and filled the rest of the way with water Then 0.500 mLs of the standard solution was transfered to a 10.00 mL flask and diluted to the 10 mL mark with 0.02 M of buffered iron chloride.  Number of moles of NaOH = 0.005 moles Since the reaction between acetylsalicylic acid and NaOH is a 1:1 reaction, the number of moles of acetylsalicylic acid used in the reaction is also 0.005 moles. the concentration from analysis question 5: acetylsalicylic acid in the 100.00 mL volumetric flask is 0.050 M. From your plot, what is the value of εb? From the Beer- Lambert law For the aspirin sample, calculate the concentration of acetylsalicylic acid present using the value of εb that you found   The concentration from analysis question 5 represents the concentration in the 10.00 mL sample that was prepared in the volumetric flask using an aliquot of the solution in the…