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27 Nov 2019

what volumes of 0.200M HNO2 and 0.200 M NaNO2 are requires to make500mL of a buffer solution with pH= 3.00? [Ka forHNO2=4.00x10^-4]

(A) 250mL of each
(B) 143 mL of HNO2 and 357 mL of NaNO2
(C) 200mL of HNO2 and 300mL of NaNO2
(D) 357mL of HNO2 and 143mL of NaNO2

I know the answer is D- I just need help with calculations. I knowwe apply the Henderson-Hasselbalch equation.
Thanks!

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Tod ThielLv2

29 Jan 2019

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Please see the information Iâve provided in bold, then fill in the blanks below #11 (A-G and the following questions). This is not a long question - I only need a few things answered, and all the information you need is here. I am just struggling with what is the "strong acid" and what numbers to put in for pH. Thanks!

Select 4 250-mL Erlenmeyer Flasks from the pictorial or equipment menu. Keep track of which one is which.

Click on the first flask and add 100 mL of distilled water to it. Click on the second flask and add 100 mL of distilled water to it.

Click on the third flask and add 74.0 mL of 0.1 M acetic acid to it. Also add 1.1 g of sodium acetate to the third flask. Finally add 26.0 mL of distilled water to the third flask. Stir the solution.

Click on the fourth flask and add 74.0 mL of 0.1 M acetic acid to it. Also add 1.1 g of sodium acetate to the fourth flask. Finally add 26.0 mL of distilled water to the fourth flask. Stir the solution.

Right click on each of the flasks and choose pH meter. The pH of each solution should appear in blue below the flask.

Record the pH of each solution on a separate WORD document.

My recordings: pH = 7. 2) pH = 7. 3) pH = 5.0127. 4) pH = 5.0127

Add 5.0 mL of HCl to the first flask. Record the pH on the Report sheet. pH 2.3222

Add 5.0 mL of NaOH to the second flask. Record the pH on the Report sheet. pH 11.6778

Add 5.0 mL of HCl to the third flask. Record the pH on the Report sheet. pH 4.9679

Add 5.0 mL of NaOH to the fourth flask. Record the pH on the Report sheet. pH 5.0590

A. Preparation the buffer solution:

initial pH of buffer solution: ____

B. Titration of a weak acid with a strong base:

initial pH of weak acid: ____

final pH of weak acid: ____

Amount of NaOH added: ____

C. Titration Curve for Weak Acid with a Strong Base

(Paste curve here, or tell me how to get it in Excel or elsewhere - this is something I need help with - not something that I can post)

D. Titration of buffer with a strong base:

pH of buffer solution: ____

Amount of NaOH added: ____

E. Titration Curve for Buffer with a Strong Base

(Paste curve here, or tell me how to get it in Excel or elsewhere - this is something I need help with - not something that I can post)

F. Titration of the buffer with a strong acid:

pH of buffer solution: ____

Amount of HCl added: ____

G. Titration Curve for Buffer with a Strong Acid

(Paste curve here, or tell me how to get it in Excel or elsewhere - this is something I need help with - not something that I can post)

Questions:

What conclusions can you draw from looking at the titration curve of the weak acid with a strong base and comparing it to the titration curve for the buffer with a strong base?

What conclusions can you draw from looking at the titration curve of the buffer with a strong base and comparing it to the titration curve for the buffer with a strong acid?

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