Please help these problems. It is from Acids, Bases, Buffers and Salts lab. c) B
ID: 511382 • Letter: P
Question
Please help these problems. It is from Acids, Bases, Buffers and Salts lab.
c) Buffer Solutions (which contains 1.0M acetic acid and 1.0M sodium acetate and 10mL of 0.10 HCl was added to each solution later.)
Molarity (Buffer)
1.0M
0.1M
0.01M
pH before acid
4.68
4.63
4.62
pH after acid
4.62
4.17
2.27
pH
0.06
0.46
2.35
1. How did diluting the buffer affect the pH of the buffer solution itself?
2. Calculate the change in pH produced by the addition of the HCl to each buffer solution. Why are the results for each of the three solutions different? (They should be)
d) Salt Solutions
Sodium Carbonate
pH 10
Ammonium Carbonate
pH 8
Ammonium Chloride
pH 6
Aluminum Chloride
pH 4
1. Examine the pH of solutions of Na2CO3, NH4Cl, (NH4)2CO3 and AlCl3.
2. Based on the pH you measured for the solution of (NH4)2CO3 is NH4+ a stronger acid or is CO32- a stronger base? Explain.
Molarity (Buffer)
1.0M
0.1M
0.01M
pH before acid
4.68
4.63
4.62
pH after acid
4.62
4.17
2.27
pH
0.06
0.46
2.35
Explanation / Answer
1. pH of the buffer does not change much on dilution
2. On dilution, buffer capacity of a buffer changes (buffer capacity is change in pH on adding acid or base).
------------------------
As the solution is slightly basic, CO3^2- is stronger base
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