18 Questions
What is the phase change that occurs at 0°C and 1 atm for pure water?
Freezing
Which of the following is a property of liquid water at room temperature?
High density
What is the shape of water molecules?
Bent
Why does liquid water have a high boiling point compared to other substances?
Formation of H-bonds
What is the only substance that contracts when cooled in its liquid form?
Water
In which state of water, liquid or solid, is the hydrogen bonding more extensive?
Solid state
What property of water is responsible for water moving upward in plants?
High Surface Tension
Which type of solid has particles arranged in a regular geometric pattern with a highly ordered and repetitive structure?
Crystalline Solid
What is the main characteristic of amorphous solids?
Particles not arranged in a regular geometric pattern
Which property of liquids is related to the significant drop in temperature during evaporation?
High heat of vaporization
What type of crystals have unit cells that repeat themselves in a definite pattern?
Sugar crystals
Which property is associated with solids having very strong forces of attraction between particles?
High densities
Which statement best describes the critical point in a phase diagram?
It is the point where the liquid and gas phases become indistinguishable.
What does the triple point in a phase diagram represent?
The point where solid, liquid, and gas phases coexist at equilibrium.
In a phase diagram, what is indicated by the normal freezing point?
The temperature and pressure at which a substance freezes under standard conditions.
What happens to CO2 when the temperature is increased from 200K to 300K at 1 atm?
Melting
In the phase diagram of carbon dioxide, what does the triple point represent?
The point where solid, liquid, and gas phases coexist at equilibrium.
What does the normal sublimation point in a phase diagram represent?
The temperature at which a solid directly transitions to gas.
Study Notes
Liquids and IMF
- Inter Molecular Forces (IMF) affect surface tension, viscosity, boiling point, heat of vaporization, and vapor pressure.
- Increasing IMF results in increased surface tension, viscosity, boiling point, and heat of vaporization, and decreased vapor pressure.
Structure and Properties of Water
- Water is a colorless, odorless, and tasteless liquid at room temperature.
- It has a bent shape, with two partially positive hydrogen atoms and a partially negative oxygen atom, making it a polar molecule.
- Water has a high boiling point, specific heat, and density in its liquid form.
- It is the only substance that contracts when cooled, due to more extensive hydrogen bonding in its solid state.
Properties of Water
- High boiling point due to strong intermolecular forces caused by hydrogen bonding.
- High specific heat (1 cal/g°C) allows water to absorb or release a large amount of heat without a change in temperature.
- High surface tension due to hydrogen bonding among water molecules, causing water to move upward.
- High heat of vaporization, requiring a large amount of heat to vaporize a given amount of water, resulting in a significant drop in temperature during evaporation.
Properties and Types of Solids
- Solids have very strong forces of attraction, definite shape and volume, and closely packed particles that vibrate in place.
- Crystalline solids have particles arranged in a regular geometric pattern, are highly ordered and repetitive, and have a fixed shape and volume.
- Amorphous solids have particles that are not arranged in a regular geometric pattern, are "supercooled liquids" with very high viscosity, and appear to have been cooled at very low temperatures.
- Unit cells are definite patterns that repeat themselves in solid crystals.
Phase Diagrams
- A phase diagram shows the relationship between temperature and pressure, and the phase changes that occur as a result of changes in these variables.
- The triple point is the point at which a substance exists as a liquid, gas, and solid all at the same time, at equilibrium.
- The critical point is the maximum temperature and pressure at which a liquid can be liquefied.
- The normal boiling point is the temperature at which a liquid boils at a pressure of 1 atm.
- The normal freezing point is the temperature at which a liquid freezes at a pressure of 1 atm.
Phase Diagram of Water
- Normal boiling point: 100°C or 373 K at 1 atm.
- Normal freezing point: 0°C or 273 K at 1 atm.
Phase Diagram of Carbon Dioxide
- Normal sublimation point: -78.5°C or 194 K at 1 atm.
- It directly goes from solid to gas, thus subliming.
Test your knowledge on the properties of water such as high surface tension and heat of vaporization, as well as the characteristics of different types of solids including crystalline and amorphous solids.
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