Question

Problem 16.45

Part A

Calculate [OH−] for 1.0×10⁻³ M Sr(OH)2.

Express your answer using two significant figures.

[OH−] =

2.0×10−3

M

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Correct

Part B

Calculate pH for 1.0×10⁻³ M Sr(OH)2.

Express your answer using two decimal places.

pH =

11.30

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Correct

Part C

Calculate [OH−] for 2.500 g of LiOH in 220.0 mL of solution.

Express your answer using four significant figures.

[OH−] =

0.4745

M

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Correct

Significant Figures Feedback: Your answer 0.4800 M was either rounded differently or used a different number of significant figures than required for this part. If you need this result for any later calculation in this item, keep all the digits and round as the final step before submitting your answer.

Part D

Calculate pH for 2.500 g of LiOH in 220.0 mL of solution.

Express your answer using four decimal places.

pH =

13.6762

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Correct

Part E

Calculate [OH−] for 1.70 mL of 0.150 M NaOH diluted to 1.50 L .

Express your answer using three significant figures.

[OH−] =

  M  

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Part F

Calculate pH for 1.70 mL of 0.150 M NaOH diluted to 1.50 L .

Express your answer using three decimal places.

pH =

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Part G

Calculate [OH−] for a solution formed by adding 5.70 mL of 0.130 M KOH to 10.0 mL of 8.4×10⁻² M Ca(OH)2.

Express your answer using two significant figures.

[OH−] =

  M  

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Part H

Calculate pH for a solution formed by adding 5.70 mL of 0.130 M KOH to 10.0 mL of 8.4×10⁻² M Ca(OH)2.

Express your answer using two decimal places.

pH =

Answer 1

(E) NaOH => Na+ + OH-

Moles of NaOH = 1.70/1000 x 0.160 = 0.000272 mol


[OH-] = [NaOH] = moles/volume of NaOH

= 0.000272/1.50

= 0.000181 M = 1.81 x 10^(-4) M


(F) pOH = -log[OH-] = -log(1.81 x 10^(-4)) = 3.742

pH = 14 - pOH = 14 - 3.74 = 10.258


(G) KOH => K+ + OH-

Ca(OH)2 => Ca2+ + 2 OH-
Moles of KOH = 6.00/1000 x 0.130 = 0.00078 mol
Moles of Ca(OH)2 = 11.0/1000 x 8.4 x 10^(-2) = 0.00084 mol
Total volume = 6.00 + 11.00 = 17.00 mL = 0.017 L
[OH-] = [KOH] + 2 x [Ca(OH)2]

= (moles of KOH + 2 x moles of Ca(OH)2)/total volume

= (0.00078 + 2 x 0.00084)/0.017

= 0.145 M

= 0.145 M