Intermolecular Forces & Solubility

13.3

Select the solubility simulation

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Considering parts 4-5 of the simulation, which of the molecules will dissolve together? Why?

1. “Like dissolves like”

1. Compounds with similar attractive forces dissolve together.
2. Polar dissolves polar (& ionic); nonpolar dissolves nonpolar.

Oil - nonpolar

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Draw the structure for octane (C₈H₁₈). Will ammonia (NH₃) dissolve in octane? Explain.

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Solubility simulation part 6: how does temperature affect the rate and amount of solute dissolved? Why?

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2. Effect of Temperature

1. Amount and speed of solvation for solid substances increases with temperature
2. Higher temperature → more motion → more dissolving

2. Effect of Temperature

c. Amount and speed of solvation for gas substances decreases with temperature

d. Higher temperature → more motion → vaporization

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Why does the color spread out? Why doesn’t it just stay where it started?

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3.Entropy

1. Entropy = a measure of order
2. Disorder is more likely than order, so random processes tend to go into disorder over time.

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Order

Disorder

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NH₄NO₃(s) → NH₄⁺(aq) + NO₃^-(aq) ΔH = 25.41 kJ/mol

Dissolving ammonium nitrate requires energy (endothermic). Why would the process happen naturally (spontaneously)?

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4. Solutions & Entropy

1. May be exothermic OR endothermic → driven by increase in entropy.