answer

watching

views

11 Dec 2019

NH3/NH4 buffer:

Mass NH4Cl used 1.3738g

volume NaOH used 21.2 ml

initial pH (0f the buffer) 9.6, pH after 1 drop HCl 9.03, pH after 10 drops HCl 8.91

Dilute NaOH solution

Initial pH 10.35

pH :1 drop HCl 10.21, 10 drops HCl 2.85

Acetate buffer (0.500)

Mass of CH3COONa * 3H2O 10.935

volume CH#COOH 44.3 ml

initial pH 4.89

1.0 ml of NaOH pH 4.93

initial volume 2.2

final volume 16.2

final pH 5.91

Acetate buffer (0.100)

Mass of CH3COONa * 3H2O 2.1603

volume CH3COOH 8.9 ml

initial volume 6.2

final volume 23.2

Initial pH 4.85

final pH 5.83

1. Show complete calculations for the buffering capacity of both the 0.500 M and 0.100 M acetate buffers.

2. Compare ability of your buffer solution to resist changes in pH with that of the strong base (NaOH). Why can the buffer resist the pH change? Comment on why NaOH does not function as a buffer.

3. How did the concentration of the buffers affect the buffering capacity? Explain your observations.

answer

watching

110

views

For unlimited access to Homework Help, a Homework+ subscription is required.

You have 0 free answers left.
Get unlimited access to 3.8 million step-by-step answers.

Get unlimited access

Already have an account? Log in

Bunny GreenfelderLv2

13 Dec 2019

Unlock all answers

Get 1 free homework help answer.

Already have an account? Log in

Join us on Discord

Chemistry Study Group

Join now

Related questions

i need help graphing this information based on data 1 and data 2 based on information below provided

Activity 1: Buffer Solution Preparation

The following eight solutions are prepared in the eight plastic cups labeled with the solution names.

1. Based on the Preparation calculations, prepared 50 mL of a 0.10 M solution of sodium acetate in the cup labeled sodium acetate. 0.050L x 0.10M= 0.005 x 82.03= .41g CH₃COONa

2. 100 mL of pure water was added to the cup labeled water

3. 50 mL of a 0.1 M acetic acid solution was added to the cup labeled acetic acid.

4. 10 mL of a 0.1 M NaOH solution (0.10M)(10mL)=(1M)(V₂)V₂=1mL NaOH

5. 10 mL of a 0.1M HCl solution (.10M)(10mL)=(1M)(V₂)V₂=1mL HCl

6. 10 mL of a pH 3.7 buffer (9.1 mL of 0.1 M acetic acid and 0.9 mL of sodium acetate)

7. 10 mL of a pH 4.7 buffer (5.0 mL of 0.1 M acetic acid and 5.0 mL of sodium acetate)

8. 10 mL of a pH 5.7 buffer (0.9 mL of 0.1 M acetic acid and 9.1 mL of sodium acetate)

The following amount of Bogenâs Universal Indicator was added to each solution: 10 drops to the acetic acid and the sodium acetate solutions, 20 drops to the 100 mL water, and 2 drops to the NaOH and the HCl solutions.

The 24-well plate was placed on to a sheet of plain white paper as shown below, and one drop of universal indicator was added to each well. The following amount of solutions was transferred the appropriate pipets to each well.

a. 1 mL of 0.1 M acetic acid to all four wells in the first row of the 24-well plate.

b. 1 mL of water to all four wells in the second row of the plate

c. 1 mL of 0.1 M sodium acetate solution to all four wells in the third row

d. 1 mL of the 3.7 pH buffer to all four wells in the fourth row

e. 1 mL of the 4.7 pH buffer to all four wells in the fifth row

f. 1 mL of the 5.7 pH buffers to all four wells in the sixth row

The color of the solution for each row was recorded, and a photo of the plate was taken.

The approximate pH of the solution was determined based on the indicator color chart.

One drop of 0.1 M HCl was added to the second well of each row, 1 drop of 0.1 M NaOH was added to the third well of each row, and 10 drops of 0.1 M NaOH was added to the fourth well of each row.

The color and corresponding pH was recorded.

A photo of the plate showing the colors in each well was taken.

	0.1M Acetic Acid	water	0.1M Sodium Acetate	pH 3.7 Buffer	pH 4.7 Buffer		pH 5.7 Buffer
Initial Color		yellow	green	pink		orange		yellow
Initial pH	4	6	7	4		5		6
Color after 1 drop HCl	Pink	Pink
pH after 1 drop HCl	4	4	7	4		5		6
Color after 1 drop NaOH	Pink	blue	blue					blue
pH after 1 drop NaOH	4	8	8	4		5		8
Color after 10 drops NaOH	Pink	purple	purple					purple
pH after 10 drops NaOH	4	10	10	4		5		10

Activity 2: Buffering Capacity of a Solution

The 24-well plate was placed on to a sheet of plain white paper at 90Â°so that it is four rows by six columns

20 mL of pH 4.7 buffer was prepared by doubling the volumes calculate in from activity 1 in the appropriate cup, and 2 mL of the solution was added into all 6 wells in the first row.

5 mL of the pH 4.7 buffer solution was diluted with 15 mL of purified water containing the indicator and poured into a clean cup. 2 mL of this first dilution was added to all the wells in the second row.

5 mL of the first dilution was diluted with 15 mL of purified water containing the indicator and poured into a clean cup. 2 mL of this second dilution was added to all the wells in the third row.

5 mL of the second dilution was diluted with 15 mL of purified water containing the indicator and poured into a clean cup. 2 mL of this third dilution was added to all the wells in the fourth row.

An additional drop of indicator was added to each well to make the color more visible. The color of the first well of each row was recorded.

One drop of 0.1 M NaOH solution was added to the second well in each row, two drops of 0.1 M NaOH solution was added to the third well of each row, three drops to the fourth well, four drops to the fifth well, and five drops to the sixth well. The color and corresponding pH of each well was recorded, and a photo of the plate showing the colors in each well was taken. The sodium acetate molar concentration of each dilution was calculated.

	pH 4.7 Buffer	First Dilution	Second Dilution	Third Dilution
Initial Color	orange	orange	orange	orange
Initial pH	5	5	5	5
Color after 1 drop NaOH	orange	orange	Blue	purple
pH after 1 drop NaOH	5	5	8	10
Color after 2 drops NaOH	orange	yellow	Blue	purple
pH after 2 drops NaOH	5	6	8	10
Color after 3 drops NaOH	orange	green	purple	purple
pH after 3 drops NaOH	5	7	9	10
Color after 4 drops NaOH	orange	purple	purple	purple
pH after 4 drops NaOH	5	9	9	10
Color after 5 drops NaOH	orange	purple	purple	purple
pH after 5 drops NaOH	5	9	9	10
Concentration of sodium acetate	0.1 M	2.5x10^-2 M	6.3x10^ -3 M	1.6x10^-3 M

Weekly leaderboard

Home

Homework Help 3,900,000

Chemistry 830,000

Unlock all answers

Related textbook solutions

Basic Chemistry

Principles of Chemistry Molecular Approach

Chemistry: Structure and Properties

Principles of Chemistry Molecular Approach

Chemistry: A Molecular Approach

Chemistry: A Molecular Approach

Principles of Chemistry: A Molecular Approach

Chemistry: The Central Science

Related questions

Weekly leaderboard