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3 years ago

Which is true of ultraviolet rays?

1 answer:

7 0

A is true of UV rays.
B is true not of UV rays but rather of visible light.
C is true not of UV rays but rather of microwaves. (unless you actually toast your toast in a toaster like a normal person)
D is true not of UV rays but rather of radio waves.

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Ka/KbMIXED PRACTICE108.Calculate the [H3O+(aq)], the pH, and the % reaction for a 0.50 mol/L HCN solution. ([H3O+(aq)] = 1.8 x 1

NeTakaya

Answer:

a) [H₃O⁺] = 1.8x10⁻⁵ M

b) pH = 4.75

c) % rxn = 3.5x10⁻³ %

Explanation:

a) The dissociation reaction of HCN is:

HCN(aq) + H₂O(l) ⇄ H₃O⁺(aq) + CN⁻(aq)

0.5 M - x x x

The dissociation constant from the above reactions is given by:

$Ka = \frac{[H_{3}O^{+}][CN^{-}]}{[HCN]} = 6.17 \cdot 10^{-10}$

$6.17 \cdot 10^{-10} = \frac{x*x}{(0.5 - x)}$

$6.17 \cdot 10^{-10}*(0.5 - x) - x^{2} = 0$

By solving the above quadratic equation we have:

x = 1.75x10⁻⁵ M = 1.8x10⁻⁵ M = [H₃O⁺] = [CN⁻]

Hence, the [H₃O⁺] is 1.8x10⁻⁵ M.

b) The pH is equal to:

$pH = -log[H_{3}O^{+}] = -log(1.75 \cdot 10^{-5} M) = 4.75$

Then, the pH of the HCN solution is 4.75.

c) The % reaction is the % ionization:

$\% = \frac{x}{[HCN]} \times 100$

$\% = \frac{1.75 \cdot 10^{-5} M}{0.5 M} \times 100$

$\% = 3.5 \cdot 10^{-3} \%$

Therefore, the % reaction or % ionization is 3.5x10⁻³ %.

I hope it helps you!

6 0

2 years ago

815 yd to km (need 3 sig fig)

SpyIntel [72]

<u>Answer:</u> The correct answer is 0.745 km

<u>Explanation:</u>

We are given:

A numerical value of 815 yards

To convert this into kilometers, we use the conversion factor:

1 km = 1093.6 yards

Converting the given value into kilometers, we get:

$\Rightarrow 815yd\times \frac{1km}{1093.6yd}=0.745km$

Hence, the correct answer is 0.745 km

5 0

3 years ago

Calculate the boiling point of a solution of 500.0 g of ethylene glycol (c2h6o2) dissolved in 500.0 g of water. kf = 1.86Â°c/m a

Bingel [31]

Answer:The boiling point of the solution is 108° C.

Explanation:

Boiling point of pure water=T= $100^oC$

Boiling point of water after addition of 500 g of ethylene glycol= $T_f$

Mass of water = 500g = 0.5 kg (1000 g = 1 kg)

$\Delta T_f=K_b\times \frac{\text{Mass of ethlyene glycol}}{\text{Molar mass of ethylene glycol}}$

$\Delta T_f=0.512^oC/m\times \frac{500 g}{62.07 g/mol\times 0.5 kg}$

$\Delta T_f=8.24 ^oC$

$\Delta T_f=T_f-T$

$8.24^oC=T_f-100^oC$

$T_f=108.24^oC$

The boiling point of the solution is 108° C.

7 0

2 years ago

How many electrons are in the highest occupied energy level of a nuetral silicon atom?

Ludmilka [50]

A). 4
.........................

3 0

3 years ago

What is strong interaction in atoms

insens350 [35]

Answer:

Alternative Titles: nuclear force, strong interaction, strong nuclear force. Strong force, a fundamental interaction of nature that acts between subatomic particles of matter. The strong force binds quarks together in clusters to make more-familiar subatomic particles, such as protons and neutrons.

5 0

2 years ago