Lesson 3 - Properties of Liquids

Liquids

Do not have a simple or regular structure, but many of their properties can be explained qualitatively by viewing them at the particulate level

Surface Tension

Property of a liquid to resist an external force and thus assume a lesser surface area

Surface Tension

Attributed to the strong attractive and cohesive forces between and among the molecules, particularly at the surface of the liquid

Surface Tension

Several manifestations of this property are the ability of water to hold a relatively heavier paper clip on int surface and to allow striders to walk on its surface

Surface Tension

Moreover, the strong cohesive forces explain why spherical water droplets form on leaves

Viscosity

Resistance of a liquid to flow

Viscosity

Loosely referred to as the thickness or thinness of a liquid

Viscosity

A glassful of water is relatively faster to pour than a glass full of oil or honey

Water is less viscous or thinner than oil or honey.

viscous

The greater the intermolecular forces, the more ___ the substance

oil

Long-chained substances like ___ have greater intermolecular forces because there are more atoms that can attract one another, contributing to the substance’s total attractive forces

Honey

__ , a concentrated solution of sugar, is also highly viscous because of the hydrogen bonding that forms as a result of the numerous –OH groups of the sugar molecules

Vapor Pressure

Pressure exerted by its vapor when in equilibrium with its liquid or solid

Vapor Pressure

This means that when a liquid or a solid substance is made to evaporate in a closed container, the gas exerts a pressure above the liquid

low vapor pressure

Substances with relatively strong intermolecular forces will have ____ because the particles will have difficulty escaping as a gas

Boiling Point

Pressure at which its vapor pressure is equal to the external or atmospheric pressure

Boiling Point

Increasing the temperature of a liquid raises the kinetic energy of its molecules until such point where the energy of the particle movement exceeds the intermolecular forces that hold them together

Boiling Point

The liquid molecules then transform to gas and are seen as bubbles that rise to the surface of the liquid and escape to the atmosphere

Normal boiling point

temperature at which a liquid boiled under an atmospheric pressure of 760 mm Hg (1 atm)

100 Celsius

Normal boiling point of water

lower, decrease

At higher altitudes, the atmospheric pressure is _____ ; hence, the boiling point will subsequently ____

Boiling Point

Influenced by the strength of its intermolecular forces

higher

The greater the attractive forces, the ____ the energy needed to increase the kinetic energy of the molecules to break these forces (Boiling Point)

(60 Celsius)

This explains why the boiling point of water is higher than that of hexane

hexane

Stronger hydrogen bonding exists in water, while a weaker dispersion force acts in ___

Molar Heat of Vaporization (ΔHvap)

Amount of heat required to vaporize one mole of a substance at its boiling point

Molar Heat of Vaporization (ΔHvap)

The application of heat disrupts the intermolecular forces of attraction of the liquid molecules and allows them to vaporize

Molar Heat of Vaporization (ΔHvap)

Also determined by the strength of the intermolecular forces between molecules

increases

Boiling point generally increases as molar heat of vaporization ____

diethyl ether

Values for ethanol are higher than those for _____ due to the former’s hydrogen bonding, dipole-dipole, and London dispersion forces

hydrogen bonding, dipole-dipole attraction

The high value for water is attributed to _____ and ____

0 Celsius, 1 atm

It turns to ice, its solid form, at ___ and ___

100 Celsius

degree when water becomes gas, or steam

bent shape

A water molecule has ___, with two partially positive hydrogen atoms and a partially negative oxygen atom. These dipoles make the overall molecule polar

hydrogen bonding

The molecules in solid and liquid water are linked by

decreases

As temperature increases, the number of linked molecules ____ because the increased kinetic energy of some of the molecules make intermolecular interaction more difficult to establish

hexagonal arrangement

The water molecules in ice have more defined ___

low density

The ___ of ice is attributed to the larger (hollow) space occupied by this arrangement

move faster

When ice is heated, the increase in energy of the molecules causes them to ___

more mobile

When the melting point is reached, the rigid open structure of the ice crystals breaks down, turning the ice into liquid water in which molecules are ____

denser

As a result, molecules can move closer together, making liquid water ___ than ice

0.917 g/cm3, 0.99984 g/cm3

At 0 Celsius, the density of ice is ___ and that of liquid water is ____