Imagine that you are in chemistry lab and need to make 1.00 L of a solution with
ID: 1015402 • Letter: I
Question
Imagine that you are in chemistry lab and need to make 1.00 L of a solution with a pH of 2.60. You have in front of you 100 mL of 6.00×102 M HCl, 100 mL of 5.00×102 M NaOH, and plenty of distilled water. You start to add HCl to a beaker of water when someone asks you a question. When you return to your dilution, you accidentally grab the wrong cylinder and add some NaOH. Once you realize your error, you assess the situation. You have 81.0 mL of HCl and 85.0 mL of NaOH left in their original containers. Part A Assuming the final solution will be diluted to 1.00 L , how much more HCl should you add to achieve the desired pH? Express your answer to three significant figures and include the appropriate units. Imagine that you are in chemistry lab and need to make 1.00 L of a solution with a pH of 2.60. You have in front of you 100 mL of 6.00×102 M HCl, 100 mL of 5.00×102 M NaOH, and plenty of distilled water. You start to add HCl to a beaker of water when someone asks you a question. When you return to your dilution, you accidentally grab the wrong cylinder and add some NaOH. Once you realize your error, you assess the situation. You have 81.0 mL of HCl and 85.0 mL of NaOH left in their original containers. Part A Assuming the final solution will be diluted to 1.00 L , how much more HCl should you add to achieve the desired pH? Express your answer to three significant figures and include the appropriate units. Imagine that you are in chemistry lab and need to make 1.00 L of a solution with a pH of 2.60. You have in front of you 100 mL of 6.00×102 M HCl, 100 mL of 5.00×102 M NaOH, and plenty of distilled water. You start to add HCl to a beaker of water when someone asks you a question. When you return to your dilution, you accidentally grab the wrong cylinder and add some NaOH. Once you realize your error, you assess the situation. You have 81.0 mL of HCl and 85.0 mL of NaOH left in their original containers. Part A Assuming the final solution will be diluted to 1.00 L , how much more HCl should you add to achieve the desired pH? Express your answer to three significant figures and include the appropriate units. Imagine that you are in chemistry lab and need to make 1.00 L of a solution with a pH of 2.60. You have in front of you 100 mL of 6.00×102 M HCl, 100 mL of 5.00×102 M NaOH, and plenty of distilled water. You start to add HCl to a beaker of water when someone asks you a question. When you return to your dilution, you accidentally grab the wrong cylinder and add some NaOH. Once you realize your error, you assess the situation. You have 81.0 mL of HCl and 85.0 mL of NaOH left in their original containers. Part A Assuming the final solution will be diluted to 1.00 L , how much more HCl should you add to achieve the desired pH? Express your answer to three significant figures and include the appropriate units.
Explanation / Answer
PH = 2.60
PH = -log10 [H+]
[H+] = 10-PH
[H+] = 10-2.60
[H+] = 100.4 x 10-3
[H+]= 2.511 x 10-3
According to the question After the addition of the NaOH
HCl volume (v1)= 81 mL NaOH volume (v2) = 85 mL
HCl concentration (M1) = 6 x 10-2 M NaOH concen (M2) = 5 x 10-2 M
The resultant concentration (M) is
M1V1 - M2V2 = MV [ V = Total concentration (v1 +v2) ]
(0.06 x 81) - (0.05 x 85) = M (V1+V2)
4.86 - 4.25 = M (81 +85)
0.61 = M x 166
M = 0.61/166 = 0.00367
166 mL (V 1)of 0.00367 M (M1) solution we have to make it in to 2.511 x 10-3 M (M) concentrated 1 litre (V) or 1000 mL of solution then the will get the PH 2.60
M1V1 +M2V2 = MV M2V2 is the added HCl values ( Take From the question)
(0.00367 x 166) + (0.06 x V2) = 0.002511 x 1000
0.60922 + 0.06 V2 = 2.511
0.06 V2 = 2.511 -0.60922
0.06 V2 = 1.90178
V2 = 31.696 mL.
Hence 31.696 mL of the HCl is need to add to get the PH 2.60 of 1 litre solution.