In a solid state, the molecules have the least amount of energy. They just stick close together and vibrate in place. As the molecules gain more energy, they are able to move around more freely. In the liquid state, the molecules have enough energy to sort of tumble over each other.
Döbereiner grouped the known elements into <em>triads</em> (sets of three) so that
• The <em>atomic mass of the middle element</em> was approximately the average of the other two
• The <em>chemical properties of the middle element</em> were between those of the other two
• The <em>physical properties of the middle element</em> were between those of the other two
One example of a triad is Li – Na – K.
(a) Atomic mass of Na = 23.0 u
Average atomic mass of Li and K = (6.9 u + 39.1 u)/2 = 46.0 u/2 = 23.0 u
(b) Li reacts slowly with water. Na reacts rapidly. Potassium reacts violently.
(c) Melting point of Na = 371 °C.
Average melting point of Li and K = (454 °C + 330 °C)/2 = 784 °C/2
= 392 °C
Answer:
Explanation:
The reaction is given as:

The reaction quotient is:
![Q_C = \dfrac{[NH_3]^2}{[N_2][H_2]^3}](https://tex.z-dn.net/?f=Q_C%20%3D%20%5Cdfrac%7B%5BNH_3%5D%5E2%7D%7B%5BN_2%5D%5BH_2%5D%5E3%7D)
From the given information:
TO find each entity in the reaction quotient, we have:
![[NH_3] = \dfrac{6.42 \times 10^{-4}}{3.5}\\ \\ NH_3 = 1.834 \times 10^{-4}](https://tex.z-dn.net/?f=%5BNH_3%5D%20%3D%20%5Cdfrac%7B6.42%20%5Ctimes%2010%5E%7B-4%7D%7D%7B3.5%7D%5C%5C%20%5C%5C%20NH_3%20%3D%201.834%20%5Ctimes%2010%5E%7B-4%7D)
![[N_2] = \dfrac{0.024 }{3.5}](https://tex.z-dn.net/?f=%5BN_2%5D%20%3D%20%5Cdfrac%7B0.024%20%7D%7B3.5%7D)
![[N_2] = 0.006857](https://tex.z-dn.net/?f=%5BN_2%5D%20%3D%200.006857)
![[H_2] =\dfrac{3.21 \times 10^{-2}}{3.5}](https://tex.z-dn.net/?f=%5BH_2%5D%20%3D%5Cdfrac%7B3.21%20%5Ctimes%2010%5E%7B-2%7D%7D%7B3.5%7D)
![[H_2] = 9.17 \times 10^{-3}](https://tex.z-dn.net/?f=%5BH_2%5D%20%3D%209.17%20%5Ctimes%2010%5E%7B-3%7D)
∴

However; given that:

By relating
, we will realize that 
The reaction is said that it is not at equilibrium and for it to be at equilibrium, then the reaction needs to proceed in the forward direction.
When you want to melt an ice, you only need the latent energy of fusion, <span>δhfus. We use the given value, then multiply this with the given amount to determine the amount of energy. Since the energy is per mole basis, use the molar mass of ice which is 18 g/mol. The solution is as follows:
</span>ΔH = 5.96 kJ/mol * 1 mol/18 g * 500 g
<em>ΔH = 165.56 kJ</em><span>
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