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balu736 [363]
2 years ago
11

A pH change can be evidence that

Chemistry
1 answer:
olganol [36]2 years ago
7 0

Answer:

Explanation:The pH scale ranges from 0 to 14. The pH of a solution is a measure of its acidity or alkalinity (base). ... A change of one unit on the pH scale represents a change in the concentration of hydrogen ions by a factor of 10, a change in two units represents a change in the concentration of hydrogen ions by a factor of 100.

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Consider the following reaction:
iren [92.7K]

Answer:

A. ΔG° = 132.5 kJ

B. ΔG° = 13.69 kJ

C. ΔG° = -58.59 kJ

Explanation:

Let's consider the following reaction.

CaCO₃(s) → CaO(s) + CO₂(g)

We can calculate the standard enthalpy of the reaction (ΔH°) using the following expression.

ΔH° = ∑np . ΔH°f(p) - ∑nr . ΔH°f(r)

where,

n: moles

ΔH°f: standard enthalpy of formation

ΔH° = 1 mol × ΔH°f(CaO(s)) + 1 mol × ΔH°f(CO₂(g)) - 1 mol × ΔH°f(CaCO₃(s))

ΔH° = 1 mol × (-635.1 kJ/mol) + 1 mol × (-393.5 kJ/mol) - 1 mol × (-1206.9 kJ/mol)

ΔH° = 178.3 kJ

We can calculate the standard entropy of the reaction (ΔS°) using the following expression.

ΔS° = ∑np . S°p - ∑nr . S°r

where,

S: standard entropy

ΔS° = 1 mol × S°(CaO(s)) + 1 mol × S°(CO₂(g)) - 1 mol × S°(CaCO₃(s))

ΔS° = 1 mol × (39.75 J/K.mol) + 1 mol × (213.74 J/K.mol) - 1 mol × (92.9 J/K.mol)

ΔS° = 160.6 J/K. = 0.1606 kJ/K.

We can calculate the standard Gibbs free energy of the reaction (ΔG°) using the following expression.

ΔG° = ΔH° - T.ΔS°

where,

T: absolute temperature

<h3>A. 285 K</h3>

ΔG° = ΔH° - T.ΔS°

ΔG° = 178.3 kJ - 285K × 0.1606 kJ/K = 132.5 kJ

<h3>B. 1025 K</h3>

ΔG° = ΔH° - T.ΔS°

ΔG° = 178.3 kJ - 1025K × 0.1606 kJ/K = 13.69 kJ

<h3>C. 1475 K</h3>

ΔG° = ΔH° - T.ΔS°

ΔG° = 178.3 kJ - 1475K × 0.1606 kJ/K = -58.59 kJ

5 0
3 years ago
Electrons returning to the ground state from varying excited states always:
nata0808 [166]

Answer:

produce characteristic sets of energies, depending on the differences in energy between the excited states and ground state

Explanation:

The electron is jumped into higher level and back into lower level by absorbing and releasing the energy.

The process is called excitation and de-excitation.

Excitation:

When the energy is provided to the atom the electrons by absorbing the energy jump to the higher energy levels. This process is called excitation. The amount of energy absorbed by the electron is exactly equal to the energy difference of orbits.  For example if electron jumped from K to L it must absorbed the energy which is equal the energy difference of these two level. The excited electron thus move back to lower energy level which is K by releasing the energy because electron can not stay longer in higher energy level and comes to ground state.

De-excitation:

When the excited electron fall back to the lower energy levels the energy is released in the form of radiations. this energy is exactly equal to the energy difference between the orbits. The characteristics bright colors are due to the these emitted radiations. These emitted radiations can be seen if they are fall in the visible region of spectrum

6 0
3 years ago
Please please help me with this chemistry question over limiting reactants it’s due by midnight! I’ll mark you BRAINIEST!!!
OverLord2011 [107]

Answer: 1.5 moles

Explanation: one mole Zn uses 2 moles HCl.

1.5 moles Zn uses 3.0 mol HCl. Then Zn is a limiting reactant

And produces equal amount of H2.

4 0
2 years ago
If an atom gains an electron it is known as what ? And has a negative charge
bekas [8.4K]
If an atom gains an electron and gets a negative charge because of it, it is a negatively charge ion AKA an anion.
6 0
3 years ago
Which of the following characteristics do all of the outer planets have in common? A. They lack moons. B. They are small and den
Bogdan [553]
I think the correct answer from the choices listed above is option D. Outer planets are mostly made up of gases and are huge in size. These gases are hydrogen and helium. <span>These outer planets are Saturn, Jupiter, Uranus, and Neptune. Hope this answers the question.</span>
8 0
2 years ago
Read 2 more answers
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