help please, the answer is not 17.14 You have in front of you 100 mL of 7.00×10

Question

help please, the answer is not 17.14

You have in front of you

100 mL of 7.00×102M HCl,

100 mL of 5.00×102M NaOH, and

plenty of distilled water.

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 2.70.

You have in front of you

100 mL of 7.00×102M HCl,

100 mL of 5.00×102M 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 80.0 mL of HCl and 86.0 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

Final pH needed = 2.70

[H+] = 2 x 10^-3 M

We have added,

20 ml of 0.07 M HCl

moles of HCl = 0.07 M x 20 ml = 1.4 mmol

14 ml of 0.05 M NaOH

moles of NaOH = 0.05 M x 14 ml = 0.7 mmol

HCl left in solution = 0.7 mmol/34 ml = 0.02 M

So, we need to make this to 0.002 M in 1 L solution

Volume of additional HCl to be added

                                                            = 18.811 ml

Related Questions

Navigate

• Browse (All)
• Browse H
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.