Sign In Sign Up Ask an AI advisor
KariSupreme
KariSupreme
08.02.2021 • 
Chemistry

Preparation of Phosphate BufferRxn: Purpose:
The purpose of lab this week is to prepare a 0.05M sodium phosphate buffer, use a pHmeter to adjust the pH of this buffer, and to calculate theoretical pH changesupon addition of acid/ base. Your theory will then be correlatedagainst your actual observational pH changes.
Solutions to be made
Molecular Weight Table
Solution
Volume
1.0M HCL
10ML
1.0 M NaOH
20ml
0.05M Sodium Phosphate: *?g NaH2PO4 H2O + *?g Na2HPO4 7H2O, pH 7.0 (buffer)
100ml
*Do the calculation of grams needed
Chemical
Molecular Weight or Stock Concentration
NaH2PO4 H2O (Monosodium phosphate, monohydrate)
137.99 g/mol
Na2HPO4 7H2O (Disodium phosphate, heptahydrate)
268.07 g/mol
NaOH
40.00 g/mol
HCl
36.46 g/mol
Notes :
Prepare the solution to ~25-50 ml less than the final volume when you anticipate adjusting the pH of the solution to allow volume for adding the acid or base. This will allow some wiggle room for adding the acid or base and won’t cause changes to your overall concentration. Once the pH is correct, add more water to bring the solution up to the final volume. 

Measure volumes in graduated cylinders; volumes marked on beakers and bottles are inaccurate. 

Stir bars are valuable and love to go down the drain. Remove your stir bar and rinse it separately from your beaker. 

Calculation
Do the following calculation: to 50 ml of sodium phosphate buffer at pH 7.0 is added 2 mL of 0.5M NaOH. Calculate the resulting pH change and show all of your working

(ii) Now actually add the 2 ml of 0.5M NaOH to 50 ml of your buffer solution and stir carefully. Measure the new pH. Compare the experimental with the theoretical result. Is the sodium phosphate still acting as a buffer? 

Preparation of Phosphate Buffer Rxn:
Purpose:
The purpose of lab this week is to prepare a 0.05M sodium phosphate buffer, use a pH meter to adjust the pH of this buffer, and to calculate theoretical pH changes upon addition of acid/ base. Your theory will then be correlated against your actual observational pH changes.
Solutions to be made
Molecular Weight Table
Solution
Volume
1.0M HCL
10ML
1.0 M NaOH
20ml
0.05M Sodium Phosphate: *?g NaH2PO4 H2O + *?g Na2HPO4 7H2O, pH 7.0 (buffer)
100ml
*Do the calculation of grams needed
Chemical
Molecular Weight or Stock Concentration
NaH2PO4 H2O (Monosodium phosphate, monohydrate)
137.99 g/mol
Na2HPO4 7H2O (Disodium phosphate, heptahydrate)
268.07 g/mol
NaOH
40.00 g/mol
HCl
36.46 g/mol
Notes :
Prepare the solution to ~25-50 ml less than the final volume when you anticipate adjusting the pH of the solution to allow volume for adding the acid or base. This will allow some wiggle room for adding the acid or base and won’t cause changes to your overall concentration. Once the pH is correct, add more water to bring the solution up to the final volume. 

Measure volumes in graduated cylinders; volumes marked on beakers and bottles are inaccurate. 

Stir bars are valuable and love to go down the drain. Remove your stir bar and rinse it separately from your beaker. 

Calculation
Do the following calculation: to 50 ml of sodium phosphate buffer at pH 7.0 is added 2 mL of 0.5M NaOH. Calculate the resulting pH change and show all of your working

(ii) Now actually add the 2 ml of 0.5M NaOH to 50 ml of your buffer solution and stir carefully. Measure the new pH. Compare the experimental with the theoretical result. Is the sodium phosphate still acting as a buffer? 

Please answer all of the QUESTIONS and do the calculation needed to start the lab. Don't just give the formula show the work also to better understand.

Solved
Show answers

Ask an AI advisor a question

I want advice