Lecture 31 Flashcards

1
Q

Explain how LDF affects bp

A

The stronger the LDF the harder it is to distrust forces so the mp & bp will be higher
-an increase in size = a stronger LDF

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2
Q

What does surface tension refer to

A

The resistance of a liquid to increase its surface area; the energy required to increase surface area by a given amount

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3
Q

Why do liquids tend to form spherical droplets

A

A surface molecule is only attracted by below and to the sides, so it experiences a net attraction downward

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4
Q

What does high surface tension imply

A

Strong intermolecular forces; the stronger the intermolecular forces between particles, the more energy it takes to increase the surface area, so the greater the surface tension

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5
Q

How does temperature affect surface tension

A

Increasing temperature: decreasing surface tension
-higher temps mean the liquid molecules have higher KE to disrupt attractions to molecules

Decreasing temperature: increasing surface tension

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6
Q

What is capillarity

A

The rising of a liquid in a tube

If the meniscus is concave: the adhesive forces are stronger than the cohesive forces

If the meniscus is convex: the cohesive forces are stronger than the adhesive forces

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7
Q

What is wetting

A

The spreading of a liquid across a surface

If the cohesive forces are stronger than the adhesive forces the water will retain shape

If the adhesive forces are stronger than the cohesive forces the liquid will spread out

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8
Q

What is viscosity

A

The resistance of liquid to flow. High viscosity implies strong IM forces

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9
Q

How does temperature affect viscosity

A

Increasing temperature: viscosity decreases because faster moving molecules overcome IM forces more easily so the resistance to flow decreases

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10
Q

How is viscosity affected by molecular shape

A
  • smaller spherical molecules make little contact so they flow easily (low viscosity)
  • larger molecules make more contact and flow slowly (high viscosity)
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11
Q

What is solubility

A

A homogeneous mixture in which the solute is dissolved in the solvent

“Like dissolves like”

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