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Harlamova29_29 [7]
3 years ago
8

Freezing involves a chemical reaction

Chemistry
2 answers:
just olya [345]3 years ago
8 0
The two main chemical reactions that are involved in the change of state are exothermic reaction and endothermic.
Just as their name suggests, endothermic is when heat is ‘taken in’ and exothermic when heat is ‘given out’.
Freezing is not a CHEMICAL CHANGE, but indeed a physical one because it goes through change of state.
So in freezing a liquid converts to a solid.
For this change to happen, temperatures need to be lower and molecules in the liquid require less energy to join together, so it releases energy in the form of heat.
This reaction will be known as EXOTHERMIC REACTION.
Bess [88]3 years ago
4 0

The same argument can be made for the process of freezing: energy is put into a liquid during melting, so freezing the liquid into a solid again returns that energy to the surroundings. Like phase changes, chemical reactions can occur with the application or release of heat.

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What is the molar mass of an element?
Vesnalui [34]

The answer is: the mass of 6.02 x 1023 representative particles of the element.

The base SI unit for molar mass is kg/mol, but chemist more use g/mol (gram per mole).

For example, molar mas of ammonia is 17.031 g/mol.

M(NH₃) = Ar(N) + 3 · Ar(H) · g/mol.

M(NH₃) = 14.007 + 3 · 1.008 · g/mol.

M(NH₃) = 17.031 g/mol.

The molar mass (M) is the mass of a given substance (in this example ammonia) divided by the amount of substance.


8 0
4 years ago
Two substances, A and Z, are to be identified. Substance A can not be broken down by a chemical change. Substance Z can be broke
I am Lyosha [343]
The answer is 3). This is because elements are the simplest form of a substance, and cannot be broken down any further. Compounds on the other hand are much more complex than elements and can be broken down INTO elements. For example, Na, sodium, is an element and cannot be broken down further. H2O, water, is a compound and can be broken down into Hydrogen and Oxygen.
4 0
3 years ago
Do ionic compounds or covalent compounds conduct electricity
Liula [17]

None because Covalent compounds don’t conduct electricity because they are formed between the non metal atoms by sharing of electrons. The Covalent compounds haves no free electrons and also no ions and hence they do not conduct electricity. That is why they do not conduct electricity.

4 0
3 years ago
A total of 25.0 mL of 0.150 M potassium hydroxide (KOH) was required to neutralize 15.0 mL of sulfuric acid (H2SO4) of unknown c
Kamila [148]
We are told that KOH is being used to completely neutral H₂SO₄ according to the following reaction:

KOH + H₂SO₄ → H₂O + KHSO₄

If KOH can completely neutralize H₂SO₄, then there must be an equal amount of moles of each as they are in a 1:1 ratio:

0.025 L x 0.150 mol/L = .00375 mol KOH

0.00375 mol KOH x 1 mole H₂SO₄/1 mole KOH = 0.00375 mol H₂SO₄

We are told we have 15 mL of H₂SO₄ initially, so now we can find the original concentration:

0.00375 mol / 0.015 L = 0.25 mol/L

The concentration of H₂SO₄ being neutralized is 0.25 M.
6 0
3 years ago
The specific heat of copper metal is 0. 385 J/(g °C). How much energy must be added to a 35. 0-gram sample of copper to change t
Rus_ich [418]

The amount of heat required for changing the temperature of copper has been 606 J. Thus, option B is correct.

Specific heat has been defined as the amount of heat required to raise the temperature of 1 gram of substance by 1 degree Celsius.

The heat required to raise the temperature has been expressed as:

\rm Heat=mass\;\times\;specific\;heat\;\times\;Change\;in\;temperature

<h3>Computation for the heat energy required</h3>

The given specific heat of copper has been \rm 0.385\;J/g^\circ C

The mass of copper has been, \rm 35\;g

The initial temperature of copper has been, \rm 20^\circ C

The final temperature of copper has been, \rm 65^\circ C

The change in temperature has been, \Delta T

\Delta T=\text{Final\;temperature-Initial\;temperature}\\\Delta T =65^\circ \text C-20^\circ \text C\\\Delta T=45^\circ \text C

Substituting the values for the heat required as:

\rm Heat=35\;g\;\times\;0.385\;J/g^\circ C\;\times\;45^\circ C\\Heat=606\;J

The amount of heat required for changing the temperature of copper has been 606 J. Thus, option B is correct.

Learn more about specific heat, here:

brainly.com/question/2094845

7 0
2 years ago
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