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liubo4ka [24]
3 years ago
10

Which of the following processes is exothermic?

Chemistry
2 answers:
Elodia [21]3 years ago
8 0

Answer:

a. The reaction associated with DHºf for an ionic compound

Explanation:

An exothermic process is a process that loses heat for the surroundings, so the temperature of the system must decrease, and ΔH must be negative.

DHºf or ΔHºf of an ionic compound is always negative because the final energy is always lower than the initial. It happens because of the stability of the bond, the system wants a lower energy state to be stable.

The ionization of a lithium atom occurs with the gain of energy, which is given to the electron, so it may give off the atom. So it's an endothermic process.

To change the state of a solid to a gas (sublimation), the compound must gain heat, its temperature must increase, so it's always an endothermic process.

To break a covalent bond it's necessary the gain of energy, so it's an endothermic process.

Korvikt [17]3 years ago
5 0

Answer:A

Explanation:

The enthalpy change of formation for an ionic compound is calculated from the Born-Haber cycle. Using the Hess law of constant heat summation. The result is always negative (exothermic) because energy is given out when the new lattice is formed.

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Luis is helping his parents paint a border around the walls of a room. He uses a stencil to repeat the same design on each wall
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Answer:

Polymerization.

Explanation:

Polymerization can be defined as a type of chemical reaction in which molecules that are relatively small in size chemically combine to form a huge chain of molecules.

Simply stated, polymerization refers to a chemical reaction where two or more smaller molecules react to produce larger molecules of the same network or repetitive structural units.

In polymerization, the relatively small molecules are generally referred to as monomers while the larger molecules they produce are known as polymers.

Polymerization is given by the chemical formula;

nA -----> A(n).

In this scenario, Luis uses a stencil to repeat the same design on each wall to form one long grapevine with a bunch of grapes every foot along its length.

Hence, the type of chemical reaction this best model is polymerization because it involved repeating the same design (monomers) to form a long grapevine with a bunch of grapes (polymers).

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3 years ago
Conner is testing the pH of a swimming pool and he finds it to be 6.5. Optimal pH for swimming is between 7.0 and 7.6.
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Answer:

The answer is B. I took the test and made a 100

Explanation:

8 0
2 years ago
Which statement is the best example of pseudoscience?
pentagon [3]
Mary thinking her astrological sign, Leo, is a perfect fit for her personality is a belief in pseudoscience because there is not scientific evidence confirming such beliefs.
The answer is the second option.
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3 years ago
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1. In general, the nucleus of a small atom is stable. Therefore, over very short distances, such as those in a small nucleus,
postnew [5]
<h3>1. <u>Answer;</u></h3>

a. the strong nuclear force is much greater than the electric force.

<h3><u>Explanation</u>;</h3>
  • <em><u>For an atom to be stable it means it has enough amount of binding energy to hold its nucleus together permanently. </u></em>
  • Therefore, <em><u>an unstable atom lacks enough amount of binding energy to hold its nucleus permanently and thus undergoes decay to achieve stability. Unstable atoms are therefore referred to being radioactive.</u></em>
  • Small atoms are stable; <u>this is because they have equal number of protons and neutrons and thus the protons and neutrons fill up energy levels while maximizing the strong force binding the nucleus together. </u>

<h3>9.<u> Answer;</u></h3>

b. change into a different element altogether.

Uranium-238 undergoes alpha decay. Therefore, uranium-238 will  <em><u>change into a different element altogether</u></em>.

<h3><u> Explanation;</u></h3>
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  • <em><u>Uranium-238 is an example of such atom, which may undergo decay to achieve stability.</u></em>
  • <em><u>Alpha decay is one of the types of decays,</u></em> others being beta decay and gamma decay. <em><u>In alpha decay the radioactive isotope undergoes decay such that its mass number is decreased by four and its atomic number is decreased by two.</u></em>
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3 years ago
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Answer:

You can infert that it has a mass of 40 grams.It also has desnity of 40 grams per millilieter.

Explanation:

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