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anygoal [31]
3 years ago
10

A 29.2 mL sample of a 0.458 M aqueous hydrofluoric acid solution is titrated with a 0.337 M aqueous sodium hydroxide solution. W

hat is the pH at the start of the titration, before any sodium hydroxide has been added
Chemistry
1 answer:
Svetach [21]3 years ago
4 0

Answer:

3.51

Explanation:

Before any sodium hydroxide has been added, the pH is that of the aqueous hydrofluoric acid solution.

HF is a weak acid that dissociates according to the following equation.

HF(aq) ⇄ H⁺(aq) + F⁻(aq)      Ka = 6.76 × 10⁻⁴

We can find [H⁺] using the following expression.

[H⁺] = √(Ca × Ka)

where

Ca: concentration of the acid

Ka: acid dissociation constant

[H⁺] = √(Ca × Ka)

[H⁺] = √(0.458 × 6.76 × 10⁻⁴)

[H⁺] = 3.10 × 10⁻⁴ M

The pH is:

pH = -log [H⁺]

pH = -log 3.10 × 10⁻⁴ = 3.51

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For the following reaction KClO4 → KCl + 2O2 Assign oxidation states to each element on each side of the equation.
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In the given reaction, potassium perchlorate decompose into potassium chlorate and oxygen.

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b)Potassium perchlorate is the reactant, Potassium chloride and Oxygen are the products.
 Reactants -----> Products

c) Check out change of OSN of elements.
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4 years ago
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Answer:

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Explanation:

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3 years ago
Cho một thực phẩm có độ ẩm tương đối là 81%, hỏi hoạt độ của nước của thực phẩm đó là bao nhiêu?
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