CHEMISTRY COLLEGE

What mass of benzoic acid would you dissolve in 350.0 mL of water to produce a solution with a pH = 2.85?

Answers

Answer 1
Answer:

The mass of the benzoic acid involved is 1.3 g.

What is pH?

The pH shows the degree of acidity or alkalinity of the solution. We have been told that the pH of this solution is 2.85. We have the reaction;

C6H5COOH ⇄C6H5COO- + H^+

Ka = [C6H5COO-] [H^+]/[C6H5COOH]

[H^+] = Antilog (-2.85) = 1.4 * 10^-3 M

6.3 x 10-5 = [1.4 * 10^-3]^2/ [C6H5COOH]

[C6H5COOH]  =  [1.4 * 10^-3]^2/ 6.3 x 10-5

[C6H5COOH]  = 1.96 * 10^-6/6.3 x 10-5

= 3.1 * 10^-2 M

number of moles = concentration * volume

number of moles = mass/molar mass

mass/molar mass = concentration * volume

mass = concentration * volume * molar mass

mass = 3.1 * 10^-2 M * 0.35 L * 122 g/mol

mass = 1.3 g

Learn more about pH: brainly.com/question/1190311

Answer 2
Answer:

Answer:

14.1391 g

Explanation:

The pH of a solution is defined as the negative of the hydrogen ion's concentration.

Thus,

pH = - log [H⁺]

Given that:

pH = 2.85

2.85 = - log [H⁺]

So,

[H⁺] = 0.0014125 M

Also, benzoic acid exists in equilibrium in water as:

C₆H₅COOH ⇄ C₆H₅COO⁻ + H⁺   Ka = 6.3×10⁻⁵

The ICE table is:

                 C₆H₅COOH ⇄ C₆H₅COO⁻ + H⁺

At t = 0             a                        0             0

At t = teq         a-x                        x            x

The expression for Ka is:

Ka = 6.3×10⁻⁵ = [C₆H₅COO⁻][H⁺] / [C₆H₅COOH]

Also,

6.3×10⁻⁵ = x.x / (a-x)

x = [H⁺] = 0.0014125 M

6.3×10⁻⁵ = (0.0014125)² / (a-0.0014125)

Solving, a = 0.3308 M

Given volume = 350.0 mL = 350.0×10⁻³ L

So, Moles of benzoic acid = Concentration×Volume

Moles = 0.3308×350.0×10⁻³ = 0.11578 moles

Mass = Molar mass × moles

Molar mass of benzoic acid = 122.12 g/mol

So,

Mass = 122.12 g/mol × 0.11578 moles = 14.1391 g


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Answers

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A compound decomposes by a first-order process. if 25.0% of the compound decomposes in 60.0 minutes, the half-life of the compound is _________. a. 65 minutes
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Answers

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Nt= N0 (1/2)^ t/h

Nt= the final mass
N0= the initial mass
t= time passed
h= half-life

If 25.0% of the compound decomposes that means the final mass would be 75% of initial mass. Then the half-live for the compound would be:
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3) Explain the difference between CO2 and C204.

Answers

Answer:

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Explanation:

Answer:

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Explanation:

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