Unit 4: Phase Changes

Intermolecular Forces

100

Define intermolecular force

The invisible forces between molecules/particles that hold them together

200

How many hydrogen bonds does this molecule have?

https://drive.google.com/file/d/14D5U80r7c4Pf8Ru0JM_hFQWgCeU8w0_G/view?usp=sharing

1

300

Explain why intermolecular forces and kinetic energy are inverse (as one goes up, the other goes down) of each other

Intermolecular forces hold molecules/particles together. When they molecules/participles are given kinetic energy, they use the energy to pull away from their IMFs, weakening then strength of them

400

Name 4 physical properties substances with STRONG intermolecular forces would have

- high boiling point

- high melting point

- high density

- low vapor pressure

- if liquid, high viscosity

- if liquid, slow evaporation

- if liquid, high surface tension

500

Rank the following in order of increasing intermolecular forces:

- dense liquid

- amorphous solid 

- molecular solid

- not dense liquid

- ionic solid

- gas

- metallic solid

gas --> not dense liquid --> dense liquid --> amorphous solid --> molecular solid --> ionic solid --> metallic solid

States of Matter

100

Which state of matter has the highest density? Explain why.

Solids because they have the strongest intermolecular forces so they are very close together and compacted

200

Draw what a substance would look like as a solid, liquid, and gas

Solid - close together, pattern

Liquid - more spread out

Gas - very spread out

300

Identify 2 differences between liquids and gasses

- liquids have stronger IMFs

- liquids have less kinetic energy

400

What type of particles make up an ionic solid? Name 2 physical properties of an ionic solid based on this

Made of ionic particles (metal + non-metal). Conductive, brittle, higher melting point

500

What type of particles make up a molecular solid? Name 2 physical properties of a molecular solid based on this

Covalent particles (non-metals). Not conductive, brittle, low melting point

Phase Changes and Phase Diagrams

100

Name the following phase changes:

- liquid --> solid

- liquid --> gas

- solid --> liquid

- gas --> liquid

- freezing

- evaporation

- melting

- condensation

200

Describe the difference between endothermic and exothermic changes

Endothermic changes absorb energy (heat), exothermic changes release energy (heat)

300

Name the two processes happening at part D of this phase change diagram:

https://drive.google.com/file/d/1UTjB7BaU5pbTDMswP20fcA32Qiwsttmn/view?usp=sharing

<-- is condensation

--> is evaporation

400

Boiling occurs when _______________ equals _______________

Vapor pressure, atmospheric pressure

500

Label all of the letters (except for b and g) on this diagram:

https://drive.google.com/file/d/1GJf5_Dsy4xv0R9nbMF-ZDQd05Ekoybjl/view?usp=sharing

a - melting/freezing

c - solid

d - liquid

e - gas

f - triple point

Heat Calculations and Dimensional Analysis

100

Elephants eat about 200 kilograms of food a day. How many grams is this?

200,000 grams

200

Identify the following phase changes as fusion or vaporization: 

- evaporation

- melting

- freezing

- condensation

- evaporation (vaporization)

- melting (fusion)

- freezing (fusion)

- condensation (vaporization)

300

Calculate the amount of heat needed in calories, to vaporize 68.2g of heptane.

5217.3cal

400

Calculate the amount of heat needed in Joules, when 4.84mol of carbon tetrachloride melts.

13068J

500

Calculate the amount of heat given off in kilocalories when 82.4kg of water condenses

44496kcal