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3 years ago

Calculate the pH of a solution prepared by mixing 50.0 mL of 0.125 M KOH and 50.0 mL of 0.125 M HCl .

Chemistry

1 answer:

Nitella [24]3 years ago

6 0

Answer: 7

Explanation:

50 ml 0.125 M KOH = (50 * 0.125) = 6.25 ml 1 M KOH

similarly 50 ml 0.125 M HCl = 6.25 ml 1 M HCl

so KOH will fully neutralize the HCl so the pH of the medium will be 7

H+ + OH- = H2O

so Kw = [H=][OH-]

= [H+]^2 = 10-14

SO [H+] = 10-7

pH = -log [H+]

pH = -log[10-7]

pH = 7

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Which isomer of 1-tert-butyl-3-ethyl-5-methylcyclohexane below is thermodynamically the most stable?

Agata [3.3K]

<h2>Answer:</h2>

Option A is correct.

<h3>Explanation:</h3>

In the options given below the isomer given in the option A of 1-tert-butyl-5-methylcyclohexane is the most stable of all. The IUPAC name for this compound is 1-tert-butyl-3-ethyl-5-methylbenzene.

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3 years ago

a bright violet line occurs at 435.8 nm in the emission spectrum of mercury vapor. What amount of energy, in joules, must be rel

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<h3>Answer:</h3>

4.56 × 10^-19 Joules

<h3>Explanation:</h3>

We are given;

Wavelength of the wave as 435.8 nm

We are required to calculate the amount of energy released by an electron.

We know that the speed of the wave, c is 2.998 × 10^8 m/s
But, c = f × λ , where f is the frequency and λ is the wavelength
Energy of a wave is given by the formula;

E = hf , where h is the plank's constant, 6.626 × 10^-34 J-s

But, f = c/λ

Therefore;

f = (2.998 × 10^8 m/s) ÷ (4.358 × 10^-7 m)

= 6.879 × 10^14 Hz

Thus;

Energy = 6.626 × 10^-34 J-s ×6.879 × 10^14 Hz

= 4.558 × 10^-19 Joules

= 4.56 × 10^-19 Joules

Therefore, the energy that must be released by the electron is 4.56 × 10^-19 Joules

7 0

3 years ago

Consider the reaction below for which K = 78.2 atm-1. A(g) + B(g) ↔ C(g) Assume that 0.386 mol C(g) is placed in the cylinder re

borishaifa [10]

Answer:

1.65 L

Explanation:

The equation for the reaction is given as:

A + B ⇄ C

where;

numbers of moles = 0.386 mol C (g)

Volume = 7.29 L

Molar concentration of C = $\frac{0.386}{7.29}$

= 0.053 M

A + B ⇄ C

Initial 0 0 0.530

Change +x +x - x

Equilibrium x x (0.0530 - x)

$K = \frac{[C]}{[A][B]}$

where

K is given as ; 78.2 atm-1.

So, we have:

$78.2=\frac{[0.0530-x]}{[x][x]}$

$78.2= \frac{(0.0530-x)}{(x^2)}$

$78.2x^2= 0.0530-x$

$78.2x^2+x-0.0530=0$

Using quadratic formula;

$\frac{-b+/-\sqrt{b^2-4ac} }{2a}$

where; a = 78.2 ; b = 1 ; c= - 0.0530

= $\frac{-b+\sqrt{b^2-4ac} }{2a}$ or $\frac{-b-\sqrt{b^2-4ac} }{2a}$

= $\frac{-(1)+\sqrt{(1)^2-4(78.2)(-0.0530)} }{2(78.2)}$ or $\frac{-(1)-\sqrt{(1)^2-4(78.2)(-0.0530)} }{2(78.2)}$

= 0.0204 or -0.0332

Going by the positive value; we have:

x = 0.0204

[A] = 0.0204

[B] = 0.0204

[C] = 0.0530 - x

= 0.0530 - 0.0204

= 0.0326

Total number of moles at equilibrium = 0.0204 + 0.0204 + 0.0326

= 0.0734

Finally, we can calculate the volume of the cylinder at equilibrium using the ideal gas; PV =nRT

if we make V the subject of the formula; we have:

$V = \frac{nRT}{P}$

where;

P (pressure) = 1 atm

n (number of moles) = 0.0734 mole

R (rate constant) = 0.0821 L-atm/mol-K

T = 273.15 K (fixed constant temperature )

V (volume) = ???

$V=\frac{(0.0734*0.0821*273.15)}{(1.00)}$

V = 1.64604

V ≅ 1.65 L

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4 years ago

Read 2 more answers

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Marrrta [24]

Explanation:

The sulfonation of the naphthalene yield 2 products under different conditions:

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The products are shown in image below.

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4 years ago