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Example: Given the following reaction, 2Na + Cl ₂ -> 2NaCl, and following mixture, [Na]=0.50M, [Cl ₂]=0.30M, [NaCl]=0.40M, what is the value of reaction quotient Q?

Q = 0.4²/(0.5²)(0.3) = 0.192

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Example: Find number of atoms in 117gr NaCl

(Calculated on the right): 117gr NaCl = 2 moles
(2mol NaCl) (6.022x10^23/1mol) = 1.20x10^24 atoms NaCl

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Example: Convert 2 moles of NaCl to grams.

(2 moles NaCl)(58.4gr/mol NaCl) = 117gr NaCl

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Example: How many moles Cl 2  needed to completely react with 15.0gr of Na(s) to form NaCl(s)?

Grams Na->Moles Na: (15.0gr Na)(1mol Na/22.9gr Na) = 0.655mol Na
Moles Na->Moles Cl2 : (0.655mol Na)(1Cl₂/2Na)= 0.328 mol Cl₂

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Amu of Na: 22.9
Amu of Cl₂: 70.8
Amu of NaCl:  58.4

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Δ𝐻∘f of Na and Cl = 0 kJ mol–1

Δ𝐻∘f of NaCl = –411.2 kJ mol–1

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ΔG = ΔH - TΔS

-ΔH and -ΔS, so ΔG can be positive at high temperature and negative & spontaneous at low temperature.

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ΔS = 2(72.1) - [2(51.3) + 223.1] = -181.5

-ΔS --> Entropy decreases, less disordered

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S°(Na) = 51.3 J/(mol·K)
S°(Cl₂) = 223.1 J/(mol·K)
S°(NaCl) = 72.1 J/(mol·K)

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Not reversible, but external intervention of electrolysis can lead to the reverse process, the decomposition of NaCl. In water, NaCl also dissolves leading to dissolution of NaCl.

2Na⁺ + Cl₂⁻ --> 2NaCl

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6.022x10^23

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According to the coefficients in equation, double the moles of Na is needed for a given quantity of moles of Cl₂ to yield desired quantity of NaCl.

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Unbalanced Equation: Na + Cl₂ -> NaCl
Cl₂ is a diatomic molecule in elemental form, it exists as 2 atoms on the left side.

Balance Cl on the right: Na + Cl₂ -> 2NaCl
Balance Na on the left: 2Na + Cl₂ -> 2NaCl

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Na and Cl combine to form a single substance, NaCl

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"Solid Sodium combines with Aqueous Chlorine to yield Solid Sodium Chloride."

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No catalyst needed due to how spontaneous the reaction between Na and Cl is. Occurs readily at room temperature with no extra application of heat.

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Increasing temperature and adding more NaCl would shift the equilibrium right (to dissolution/decomposition into ions)

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K = [NaCl]² / [Na]²[Cl₂]
Concentrations at equilibrium

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q = [NaCl]² / [Na]²[Cl₂]
Given concentrations; If Q=K, reaction is at equilibrium

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Non-spontaneous in reverse reaction due to how stable NaCl is. The ionic bond between Na⁺ and Cl⁻ ions are too strong for the reaction to spontaneously occur in the reverse direction.

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Highly spontaneous in room temperature due to large difference in electronegativity between Na⁺ and Cl₂⁻

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ΔH = 2(-411.2) - [2(0) + 0 ] = -822.4 kJ mol–1

-ΔH --> exothermic reaction with release of heat energy

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NaCl(s) → Na⁺(aq) + Cl⁻(aq)
No spectator ions

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Ionic bond between metal cation, Na+, and nonmetal anion, Cl-

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Transfer of 1 electron from Na (+1 charge) to Cl (-1 charge) in order to form stable electron configuration. Since Na has a valence shell with only 1 electron, it is more likely to transfer to the nearly-full valence shell of Cl with 7 electrons to stabilize it.

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Na is a metal, Cl is a nonmetal
Na exists in group 1 and Cl in group 17

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Empirical: 2Na(s) + Cl₂(g) --> 2NaCl(s)

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Na: +1 charge, highly reactive, silvery-white metallic, soft, malleable
Cl: -1 charge, highly reactive, greenish-yellow gas
NaCl: neutral charge, white crystalline, high melting point, soluble, neutral pH

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At room temperature, Na is a solid, Cl is a gas; combined together forms a solid, NaCl (Table salt)

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Understood through the formation of Table Salt, NaCl