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3 years ago

MARKING BRAINLEIST + 20 POINTS Explain why energy must be added to a solid to cause it to melt?

1 answer:

4 0

Energy is required to melt a solid because the cohesive bonds between the molecules in the solid must be broken apart so that the molecules can move around at comparable kinetic energies

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Calculate ∆G ◦ r for the decomposition of mercury(II) oxide 2 HgO(s) → 2 Hg(ℓ) + O2(g) ∆H◦ f −90.83 − − (kJ · mol−1 ) ∆S ◦ m 70.

bagirrra123 [75]

Answer:

4. +117,1 kJ/mol

Explanation:

ΔG of a reaction is:

ΔGr = ΔHr - TΔSr (1)

For the reaction:

2 HgO(s) → 2 Hg(l) + O₂(g)

ΔHr: 2ΔHf Hg(l) + ΔHf O₂(g) - 2ΔHf HgO(s)

As ΔHf of Hg(l) and ΔHf O₂(g) are 0:

ΔHr: - 2ΔHf HgO(s) = 181,66 kJ/mol

In the same way ΔSr is:

ΔSr= 2ΔS° Hg(l) + ΔS° O₂(g) - 2ΔS° HgO(s)

ΔSr= 2* 76,02J/Kmol + 205,14 J/Kmol - 2*70,19 J/Kmol

ΔSr= 216,8 J/Kmol = 0,216 kJ/Kmol

Thus, ΔGr at 298K is:

ΔGr = 181,66 kJ/mol - 298K*0,216kJ/Kmol

ΔGr = +117,3 kJ/mol ≈ 4. +117,1 kJ/mol

I hope it helps!

5 0

3 years ago

BRAINLIEST PLEASE HELP!!!

Natalka [10]

Answer : first opinion and also last
Expiation : Note that these last two reactions, and 2H + 2H → 4He + γ, .Nuclear fusion is a reaction in which two nuclei are combined to form a larger nucleus. Nuclear fusion is a reaction in which two nuclei are combined, or fused, to form a larger nucleus. We know that all nuclei have less mass than the sum of the masses of the protons and neutrons that form them. The missing mass times c2 equals the binding energy of the nucleus—the greater the binding energy, the greater the missing mass.

5 0

3 years ago

State the oxidation number assigned to each bold element in the formula: NH4+1 a 3 b -3 c -1 d 6

Leya [2.2K]

The fomula is NH4 (1+)

There are only two elements N and H.

As per oxidation state rules, the most electronegative element will have a negative oxidation state and the other element will have a positive oxidation state.

N is more electronative than H, so H will have a positive oxidation state and nitrogen will have a negative oxidation state.

You can also use the rule that states the hydrogen mostly has 1+ oxidation state,except when it is bonded to metals.

In conclusion the oxidation state of H in NH4 (1+) is 1+.

Now you must know that the sum of the oxidations states equals the charge of the ion, which in this case is 1+.

That implies that 4* (1+) + x = 1+

=> x = (1+) - 4(+) = 3-

Answer: the oxidation state of N is 3-, that is the option b.

8 0

3 years ago

As shown by the periodic table, why do the elements potassium and sodium have similar chemical properties?

nadya68 [22]

Hey mate
This is the answer

The elements potassium and sodium have similar chemical properties because they have the same number of valence electrons and form +1 ions.

Plsssssss mark me as brainliest

3 0

3 years ago

A balloon filled with air has a volume of 6.50 L, a pressure of 0.900 atm, and a temperature of 25.0oC. If it is left out overni

kari74 [83]

Answer:

4.92 L

Explanation:

Rearrange ideal gas law and solve.

Change C to K.

- Hope that helps! Please let me know if you need further explanation.

8 0

3 years ago