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3 years ago

Arrange the events in the life of a star in the correct order.

Chemistry

1 answer:

tatiyna3 years ago

3 0

Answer:

1. The temperature increases in the center of a nebula, and nuclei begin to fuse.

2. As the nuclear fusion sets off a chain reaction, the nebula gets hotter and brighter and turns into a star.

3. The star stays in the main sequence stage for a long time.

4. The star runs out of hydrogen and turns into a planetary nebula or a supernova, depending on its mass.

5. Heavy elements are created when the supernova explodes.

6. All that remains of the star now is the core. In some cases, the star turns into a black hole.

Explanation:

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An electrochemical cell has the following standard cell notation: Al(s) | Al3+(aq) || Mg2+(aq) | Mg(s)

Soloha48 [4]

Answer:

a. Al(s) ⇄ Al⁺³(aq) + 3e⁻ (oxidation)

Mg²⁺(aq) + 2e⁻ ⇄ Mg(s) (reduction)

b. ΔE° = + 0.715 V

c. It's an electrolytic cell, because it's a nonspontaneous reaction.

d. 2Al(s) + 3Mg²⁺(aq) ⇄ 2Al⁺³(aq) + 3Mg(s)

Explanation:

a. By the notation given, first is represented the oxidation reaction and then the reduction reaction, so they are:

Al(s) ⇄ Al⁺³(aq) + 3e⁻ (oxidation)

Mg²⁺(aq) + 2e⁻ ⇄ Mg(s) (reduction)

b. The standard potential of the cell (ΔE°) is the reduction potential of the oxidation less the reduction potential of the reduction. The reduction potentials are:

Al(s) = -1.66 V

Mg(s) = -2.375 V

ΔE° = -1.66 - (-2.375)

ΔE° = + 0.715 V

c. It's an electrolytic cell.

A galvanic cell is spontaneous, so the cathode (reduction) has a higher E° than the cathode (oxidation). In this case, the oxidation reaction has a higher E°, so the reaction is nonspontaneous and it's necessary an external force to it happen, so it's an electrolytic cell.

d. 2Al(s) + 3Mg²⁺(aq) ⇄ 2Al⁺³(aq) + 3Mg(s)

The number of electrons must be the same, so the oxidation reaction is multiplied by 2, and the reduction reaction by 3.

5 0

3 years ago

Which is stronger - the attractive forces between water molecules and chromium and chloride ions, or the combined ionic bond str

Allisa [31]

Out of the two, the forces between water molecules and chromium and chloride ions is greater. This is proven by the fact that chromium chloride is slightly soluble in water, about 565 grams per liter.
In order for a substance to be soluble, the attraction of the ions to the water molecules must exceed the attraction between its own molecules and the water molecules.

3 0

2 years ago

Write the molecular formula for the following compound.

Sholpan [36]

Answer : The molecular formula of the compound is, $C_8H_9O_3N$

Explanation :

Molecular formula : It is the representation of substance by the symbols and it denotes the number of atoms of each element present in the compound.

Now count the number of carbon, hydrogen, nitrogen and oxygen atoms present in the given compound.

As we see that in the given compound, there are 8 atoms of carbon element, 3 atoms of oxygen element, 1 atom of nitrogen element, 9 atoms of hydrogen element.

Thus, the molecular formula of the compound will be $C_8H_9O_3N$

7 0

2 years ago

Can Iron replace Hydrogen in the following reaction?: Fe(s) + HCl(aq) ---> H2(g) + FeCl2(aq)

Elenna [48]

It can because Iron is more reactive than Hydrogen and a more reactive metal always replaces a less reactive one in a single replacement reaction

3 0

3 years ago

Sulfuric acid (H₂SO₄), is formed when sulfur dioxide (SO₂) reacts with oxygen and water. Using the balanced chemical reaction ab

Lynna [10]

Answer:

8.5 mol H₂SO₄

Explanation:

It seems the balanced reaction the problem is referring to is absent, however the description matches the following balanced reaction:

2SO₂ + O₂ + 2H₂O → 2H₂SO₄

Now we can convert 8.5 moles of SO₂ into moles of H₂SO₄, using the stoichiometric coefficients of the balanced reaction:

8.5 mol SO₂ * $\frac{2molH_2SO_4}{2molSO_2}$ = 8.5 mol H₂SO₄

5 0

3 years ago