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kolezko [41]
3 years ago
5

in 4 season countries, the temperatire may drop till below 0°c during the peak of winter. why does the surface of the river or l

ake freeze?​
Chemistry
1 answer:
nikitadnepr [17]3 years ago
4 0

Answer:

Explained below

Explanation:

Normally, when the temperature of water gets colder than 4° C, it starts expanding and will become less dense the colder it becomes. As the temperature gets closer to freezing point, the colder water will float to the top and the warmer water sinks to the bottom. This is mainly because of how the density of water behaves with falling temperatures.

Thus, the lake/river water will freeze from top to down as a a result of that phenomenon of colder water floating to the top and the warmer water sinking to the bottom.

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What mineral property is illustrated by this photograph?​
lbvjy [14]
<h2>Hardness, lustre, and colour.</h2>

Explanation:

These Rocks shown in photographs are made of different types of minerals which have properties as follows:

●The color of the rock is grey, brown and yellow after it is ground into a powder its color is streak.

● The lustre of the rock tells how shiny the rocks are.

● Other properties include hardness, texture, shape, and size.

7 0
3 years ago
Calculate the pH of a solution prepared by mixing: (Show your work for these calculations) pk of acetic acid is 4.75 a. two mole
kupik [55]

Answer:

Explanation:

To calculate pH you need to use Henderson-Hasselbalch formula:

pH = pka + log₁₀ \frac{[A^-]}{[HA]}

Where HA is the acid concentration and A⁻ is the conjugate base concentration.

The equilibrium of acetic acid is:

CH₃COOH ⇄ CH₃COO⁻ + H⁺ pka: 4,75

Where <em>CH₃COOH </em>is the acid and <em>CH₃COO⁻ </em>is the conjugate base.

Thus, Henderson-Hasselbalch formula for acetic acid equilibrium is:

pH = 4,75 + log₁₀ \frac{[CH_{3}COO^-]}{[CH_{3}COOH]}

a) The pH is:

pH = 4,75 + log₁₀ \frac{[2 mol]}{[2 mol]}

<em>pH = 4,75</em>

<em></em>

b) The pH is:

pH = 4,75 + log₁₀ \frac{[2 mol]}{[1mol]}

<em>pH = 5,05</em>

<em></em>

I hope it helps!

7 0
4 years ago
exactly 1mol of n2o4 is placed in an empty 1 l container. if at equilibrium n2o4 is dissociated 20%, what is the value of equili
egoroff_w [7]

Answer:

K = 0.2

Explanation:

Based on the chemical dissociation of N₂O₄:

N₂O₄ ⇄ 2NO₂

The equilibrium constant, K, of the reaction is:

K = [NO₂]² / [N₂O₄]

Now, if 20% of N₂O₄ is dissociated, 80% remains as N₂O₄ = 0.8mol/L = 0.8M

as 20% is dissociated, 0.2moles of N₂O₄ were dissociated and 0.2*2 = 0.4mol/L of NO₂ are produced.

Replacing in K:

K = [0.4M]² / [0.8M]

<h3>K = 0.2</h3>
5 0
3 years ago
An acid, like HCI, would...
frosja888 [35]

Answer: melt

Explanation:

6 0
4 years ago
Read 2 more answers
How is the mantle different from the core?​
Pepsi [2]

Answer:The Earth's mantle is made up of semisolid rocks. ... The core consists of extremely hot metal layers instead of rock. Iron and nickel make up the outer section of the core, while the interior is almost entirely iron. The inner core is almost totally solid and shaped like a ball.

Explanation:

3 0
4 years ago
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