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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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Answer:

P = 164 Atm

Explanation:

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R = 0.08206 L·Atm/mol·K

T = 27.0°C = 300 K

V = 1.50 Liters

P = (10.0 mol)(0.08206 L·Atm/mol·K )(300 K)/(1.50 Liters) = 164.12 Atm ≅ 164 Atm (3 sig. figs.)

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3 years ago
Explain why the total amount of energy does not decrease in an exergonic <br> chemical reaction
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Symbolically, the release of free energy, G, in an exergonic reaction (at constant pressure and temperature) is denoted as

{\displaystyle \Delta G=G_{\rm {products}}-G_{\rm {reactants}}<0.\,}

Although exergonic reactions are said to occur spontaneously, this does not imply that the reaction will take place at an observable rate. For instance, the disproportionation of hydrogen peroxide is very slow in the absence of a suitable catalyst. It has been suggested that eager would be a more intuitive term in this context.[2]

More generally, the terms exergonic and endergonic relate to the free energy change in any process, not just chemical reactions. An example of an exergonic reaction is cellular respiration. This relates to the degrees of freedom as a consequence of entropy, the temperature, and the difference in heat released or absorbed.

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3 years ago
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iragen [17]

Answer:

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Explanation:

Solids are one of the three states of matter and, unlike liquids or gases, they have a definite shape that is not easy to change. Different solids have particular properties such as stretch, STRENGTH, or hardness that make them useful for different jobs.

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A plasma is a gas that has been energized to the point that some of the electrons break free from, but travel with, their nucleus.

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