Hey! I need some chemistry homework help please.?

2016-05-09 8:45 pm

7. Calculate the pH of each of the following solutions.
(a) 5.3 ✕ 10-4 M Ba(OH)2
(b) 4.1 ✕ 10-4 M HNO3

10. The pOH of a solution is 8.80. Calculate the hydrogen ion concentration of the solution.

11. A solution is made by dissolving 16.3 g of HCl in 703 mL of water. Calculate the pH of the solution. (Assume that the volume remains constant.)

回答 (1)

胡雪8°

2016-05-09 9:16 pm

✔ 最佳答案

7.
(a)
The dissociation of 1 mole of Ba(OH)₂ gives 2 moles of OH⁻ ions.
[OH⁻] = (5.3 × 10⁻⁴) × 2 = 1.06 × 10⁻³

pH = 14.0 - pOH = 14 - (-log(1.06 × 10⁻³) = 11.0

(b)
1 mole of HNO₃ gives 1 mole of H⁺ ions.
[H⁺] = 4.1 × 10⁻⁴

pH = -log(4.1 × 10⁻⁴) = 3.4

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10.
pOH = 8.8
pH = 14 - pOH = 14 - 8.8 = 5.2

[H⁺] = 10⁻⁵·² = 6.31 × 10⁻⁶ M

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11.
Molar mass of HCl = 1.01 + 35.45 = 36.46 g/mol
Number of moles of HCl = (16.3 g) / (36.46 g/mol) = 16.3/36.46 mol

Volume of the solution = 703 mL = 0.703 L

[HCl] = (16.3/36.46 mol) / (0.703 L) = 0.636 M

The dissociation of 1 mole of HCl gives 1 mole of H⁺ ions.
[H⁺] = 0.636 M
pH = -log(0.636) = 0.2

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