Question

Calculate the [H3O+] and pH of each of the following H2SO4 solutions.

Part A Part complete Calculate the [H3O+] for 0.50 Msolution. Express your answer using two significant figures. [H3O+] = 0.51   M   SubmitPrevious Answers Correct Significant Figures Feedback: Your answer .500 M was either rounded differently or used a different number of significant figures than required for this part. Part B Calculate pH for 0.50 M solution. Express your answer using two decimal places pH= . 30.30 SubmitPrevious AnswersRequest Answer Incorrect; Try Again; 5 attempts remaining Not quite. Check through your calculations; you may have made a rounding error or used the wrong number of significant figures. Part C Calculate the [H3O+] for 0.10 Msolution. Express your answer using two significant figures. [H3O+]= 9.69.6 M SubmitPrevious AnswersRequest Answer Incorrect; Try Again; 5 attempts remaining Part D Calculate pH for 0.10 M solution. Express your answer using two decimal places pH= nothing SubmitRequest Answer Part E Calculate the [H3O+] for 0.05 Msolution. Express your answer using two significant figures. [H3O+]= nothing M SubmitRequest Answer Part F Calculate pH for 0.05 M solution. Express your answer using two decimal places pH= nothing

Answer 1

Ans. #A. Balanced reaction:            H₂SO₄(aq) + 2H₂O ----> 2 H₃O⁺(aq) + SO₄^2-(aq)

Following stoichiometry of balanced reaction, 1 mol H₂SO₄ yields 2 mol H3O+ upon complete dissociation.

So,

            [H₃O⁺] = 2 x [H₂SO₄] = 2 x 0.50 M = 1.00 M

#B. From #A, we have [H₃O⁺] in 0.50 M H₂SO₄ soln. = 1.00 M

Now, pH = -log [H₃O⁺] = -log 1.00 = 0.00

#C. Given, [H₂SO₄] = 0.10 M

So, [H₃O⁺] = 2 x [H₂SO₄] = 2 x 0.10 M = 0.20 M

#D. From #C, we have [H₃O⁺] in 0.10 M H₂SO₄ soln. = 0.20 M

Now, pH = -log [H₃O⁺] = -log 0.20 = 0.70

#E. Given, [H₂SO₄] = 0.05 M

So, [H₃O⁺] = 2 x [H₂SO₄] = 2 x 0.05 M = 0.10 M

#D. From #E, we have [H₃O⁺] in 0.05 M H₂SO₄ soln. = 0.10 M

Now, pH = -log [H₃O⁺] = -log 0.10 = 1.00