Secure https://session.masteringchemistry. Chem 102 Winter 2017 Buters Mixing St

Question

Secure https://session.masteringchemistry. Chem 102 Winter 2017 Buters Mixing Strong Acids and Bases t Mixing Strong Acids and Bases Imagine that you are in chemistry lab and need to make 1.00 L of a solution with a pH of2.70. You have in front of you 100 mL bf 6.00x10 2 MHC, mL of 5.00x10 2 M NaOH, and plenty of distilled water, You start to add HCIto a beaker of water when someone asks you a question. When you retum to your dilution, you accidentally grab the wrong cylinder and add some NaOH Onoe you realize your error, you assess the situation You have 85.0 mL of HCI and B5.0 mL of NaOH left in their original containers. Mastoringchemistry Buffers assignmentProblemID: 76268723 Close previous 4 of 5 next Part A Assuming the final solytion wi be dauted to 1.00 L,how much more HCI should you add to achieve the desired pH? Express your answer to three significant figures and inelude the appropriate units. 27.9 mL Submit Hints My Answers Giveup Review Part Incorrect: Try Again: 5 attempts remaining Eeedback Continue

Explanation / Answer

Given that; pH = 2.70

NaOH = 85.0 mL of 6.00*10^-2 M

HCl = 85.0 mL of 6.00*10^-2 M

Final volume of solution = 1.0 L

Moels of acid = moalrity * volume in L

= 6.00*10^-2 M *0.085 L

= 5.1*1^-3 moles

Moels of base = moalrity * volume in L

= 6.00*10^-2 M *0.085 L

= 5.1*1^-3 moles

Reaction of acid and base

HCl + NaOH = NaCl + H2O

Both HCl and NaOH are strong electrolytes and ionizes completely.

Here all HCl reacted with NaOH and the solution is neutral.

pH = - log (H+)

H+ = 10^-pH

= 10^-2.70

= 1.99*10^-3 Moles HCl or H+ in 1 L

Thus to maintain the pH 2.70 we need 1.99*10^-3 Moles HCl or H+ in 1 L

Molarity = number of moles / volume in L

6.00*10^-2 Moles / L = 1.99*10^-3 Moles / volume in L

volume in L= 0.0333 L

=33.3 ml HCl

Thus add 33.3 ml HCl and make 1 L solution with water

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