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3 years ago

Yo can someone explain the heat of fusion and heat of vaporization thing to me?

Chemistry

1 answer:

tamaranim1 [39]3 years ago

8 0

Answer:

The heat of fusion is the amount of energy required to change a solid into a liquid at its melting point. When a liquid becomes a solid, freezing or solidification has occurred. The heat of vaporization is the energy required to change a liquid into a gas at its boiling point.

Explanation:

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Leya [2.2K]

Answer:

V₂ = 530.5 mL

Explanation:

Given data:

Initial temperature = 20.0°C

Final temperature = 40.0 °C

Final volume = 585 mL

Initial volume = ?

Solution:

Initial temperature = 20.0°C (20+273 = 293 K)

Final temperature = 40.0 °C (40+273 = 323 K)

Solution:

The given problem will be solve through the Charles Law.

According to this law, The volume of given amount of a gas is directly proportional to its temperature at constant number of moles and pressure.

Mathematical expression:

V₁/T₁ = V₂/T₂

V₁ = Initial volume

T₁ = Initial temperature

V₂ = Final volume

T₂ = Final temperature

Now we will put the values in formula.

V₁/T₁ = V₂/T₂

V₁ = V₂T₁ /T₂

V₂ = 585 mL × 293 K / 323 K

V₂ = 171405 mL.K / 323 K

V₂ = 530.5 mL

6 0

3 years ago

A Saint Bernard and a Chihuahua are of the same species but look very different. It is possible to breed the two and get a puppy

iVinArrow [24]

Answer:

Because of the breeds

Explanation:

Like in humans, the dogs belong to the same scientific group, but through the passing of time, there has been some changes in their DNA, slightly differences that make the size, the hair, and another traits to be different.

In humans all the "breeds" suffer the same changes, that is the reason that spite we are homo sapiens, there are different groups of humans as the oriental, Caucasian, etc.

7 0

4 years ago

Energy is just like any other chemical or physical process, where it cannot be created or destroyed. Which Law states this fact?

Studentka2010 [4]

The answer should be law of conservation of energy

3 0

3 years ago

What is acid rain and which fossil fuels causes acid rain?

Alekssandra [29.7K]

Answer:

Acid rain this results when gaseous emissions of sulphur oxide, nitrogen oxide etc come in contact with water vapour and sunlight and are chemically converted to strong acidic compounds such as sulphuric acid, nitric acid etc, and are carried to the earth by rain drops, snow flakes, flog or dew.

7 0

3 years ago

A 1-liter solution contains 0.494 M hydrofluoric acid and 0.371 M potassium fluoride. Addition of 0.408 moles of hydrochloric ac

UkoKoshka [18]

Answer:

Option f: an addition of HCl will exceed the buffer capacity. The option d is also correct since it is a consequence of the option f.

Explanation:

The pH of the buffer solution before the addition of HCl is:

$pH = pKa + log(\frac{[KF]}{[HF]})$

$pH = -log(6.8 \cdot 10^{-4}) + log(\frac{0.371}{0.494}) = 3.04$

The hydrochloric acid added will react with the potassium fluoride as follows:

H₃O⁺(aq) + F⁻(aq) ⇄ HF(aq) + H₂O(l)

The number of moles (η) of potassium fluoride (KF) and the HF before the addition of HCl is:

$\eta_{KF}_{i} = C_{KF}*V = 0.371 M*1 L = 0.371 mol$

$\eta_{HF}_{i} = C_{HF}*V = 0.494 M*1 L = 0.494 moles$

The number of moles of the HCl added is 0.408 moles. Since the number of moles of HCl is bigger thant the number of moles of KF, the moles of HCl that remains after the reaction is:

$\eta_{HCl} = \eta_{HCl} - \eta_{KF}_{i} = 0.408 moles - 0.371 moles = 0.037 moles$

Hence, the KF is totally consumed after the reaction with HCl and thus, exceding the buffer capacity.

We can calculate the pH after the addition of HCl:

HF(aq) + H₂O(l) ⇄ F⁻(aq) + H₃O⁺(aq) (1)

The number of moles of HF after the reaction of KF with HCl is:

$\eta_{HF} = 0.494 moles + (0.408 moles - 0.371 moles) = 0.531 moles$

And the concentration of HF after the reaction of KF with HCl is is:

$C_{HF} = \frac{\eta_{HF}}{V} = \frac{0.531 moles}{1 L} = 0.531 moles/L$

Now, from the equilibrium of equation (1) we have:

$Ka = \frac{[H_{3}O^{+}][F^{-}]}{[HF]}$

$Ka = \frac{x^{2}}{0.531 - x}$ (2)

By solving equation (2) for x we have:

x = 0.0187

Finally, the pH after the addition of HCl is:

$pH = -log (H_{3}O^{+}) = -log (0.0187) = 1.73$

Therefore, the addition of HCl will exceed the buffer capacity and thus, lower the pH by several units. The correct option is f: an addition of HCl will exceed the buffer capacity. The option d is also correct since it is a consequence of the option f.

I hope it helps you!

8 0

4 years ago