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2 years ago

Calculate the energy of a photon with a frequency of 2.36 x 10-19 Hz.

Chemistry

1 answer:

OlgaM077 [116]2 years ago

6 0

Answer:

Explanation:

energy for photon is calculated in same wasy as for electromagnetic radiation

energy for electromagnetic radiation = hf

where f is the frequency of photon

h is Planck's constant = h = 4.14 × 10−15 eV · s.

thus

energy of photon = 4.14 × 10−15 eV · s * 2.36 x 10-19 Hz

energy of photon = 9.77 * 10−(-15+ -19) eV

energy of photon = 9.77 * 10−34eV answer

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The slight positive charges on the hydrogen atoms in water molecules attract the slight negative charges on the oxygen atoms of the other water molecules

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3 years ago

What is the electronegativity of this and how do you get it?

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3 years ago

Determine the percent ionization of a 0.225 M solution of benzoic acid. Express your answer using two significant figures.

Assoli18 [71]

Answer:

1.68% is ionized

Explanation:

The Ka of benzoic acid, C₇H₆O₂, is 6.46x10⁻⁵, the equilibrium in water of this acid is:

C₇H₆O₂(aq) + H₂O(l) ⇄ C₇H₅O₂⁻(aq) + H₃O⁺(aq)

Ka = 6.46x10⁻⁵ = [C₇H₅O₂⁻] [H₃O⁺] / [C₇H₆O₂]

<em>Where [] are concentrations in equilibrium</em>

In equilibrium, some 0.225M of the acid will react producing both C₇H₅O₂⁻ and H₃O⁺, the equilibrium concentrations are:

[C₇H₆O₂] = 0.225-X

[C₇H₅O₂⁻] = X

[H₃O⁺] = X

Replacing:

6.46x10⁻⁵ = [X] [X] / [0.225-X]

1.4535x10⁻⁵ - 6.46x10⁻⁵X = X²

1.4535x10⁻⁵ - 6.46x10⁻⁵X - X² = 0

Solving for X:

X = -0.0038. False solution, there is no negative concentrations.

X = 0.00378M. Right solution.

That means percent ionization (100 times Amount of benzoic acid ionized over the initial concentration of the acid) is:

0.00378M / 0.225M * 100 =

<h3>1.68% is ionized</h3>

8 0

2 years ago

Phenolphthalein is an indicator that turns from colorless (acidic form) to magenta (basic form) and has a pKa of 9.40. What is t

frosja888 [35]

Answer:

40:1 is the ratio of the magenta phenolphthalein concentration to the colorless phenolphthalein concentration.

Explanation:

To calculate the pH of acidic buffer, we use the equation given by Henderson Hasselbalch:

$pH=pK_a+\log(\frac{[salt]}{[acid]})$

$pH=pK_a+\log(\frac{[magenta(Php)]}{[Php]})$

We are given:

$pK_a$ = negative logarithm of acid dissociation constant of phenolphthalein = 9.40

$[magenta(Php)]$ = concentration of magenta phenolphthalein

$[Php]$ = concentration of colorless phenolphthalein

pH = 11

Putting values in above equation, we get:

$11=9.40+\log(\frac{[magenta(Php)]}{[Php]})$

$\log(\frac{[magenta(Php)]}{[Php]})=11-9.40=1.6$

$\frac{[magenta(Php)]}{[Php]}=10^{1.6}=39.81 :1 \approx 40:1$

40:1 is the ratio of the magenta phenolphthalein concentration to the colorless phenolphthalein concentration.

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3 years ago