Chapter 8 Solids, liquids and gases

There are exactly ========= torr in 1 atm.

760

Pascal

One pascal is not a very large amount of pressure.

Initial advances in the understanding of gas behavior were made in the mid 1600s by

Robert Boyle

Name a common substance that forms a crystal in its solid state.

Sodium chloride

According to the kinetic theory of gases, the individual gas particles are (always, frequently, never) moving.

always

The ideal gas law

elates the four independent properties of a gas under any conditions.

What are the general properties of solids?

hard, specific volume and shape, high density, cannot be compressed

nonpolar covalent bond

has an equal sharing of electrons, as in a covalent bond with the same atom on each side

Arrange the following pressure quantities in order from smallest to largest: 1 mmHg, 1 Pa, and 1 atm.

1 Pa < 1 mmHg < 1 atm

Write a conversion factor to determine how many atmospheres are in 1,547 mmHg.

1 atm = 760 torr 1,547 torr x 1 atm ------- = 2.04 atm 760 tor

In weather forecasting, barometric pressure is expressed in inches of mercury (in. Hg), where there are exactly 25.4 mmHg in every 1 in. Hg. What is the barometric pressure in millimeters of mercury if the barometric pressure is reported as 30.21 in. Hg

1 inch of HG = 25.4 mmhg 25.4 mmhg x 30.21 Hg _______________ = 767 hg 1 mmhg

Convert 760 torr into pascals.

1 torr = 133.322 pas 760 torr x 133.322 pas -------------- = 101325 pas 1 torr

What state or states of matter does each statement, describe? 1. This state has a definite volume. 2. This state has no definite shape. 3. This state allows the individual particles to move about while remaining in contact.

1. This statement describes either the liquid state or the solid state. 2. This statement describes either the liquid state or the gas state. 3. This statement describes the liquid state.

What intermolecular forces besides dispersion forces, if any, exist in each substance? Are any of these substances solids at room temperature? 1. potassium chloride (KCl) 2. ethanol (C2H5OH) 3. bromine (Br2)

1. ionic forces 2. dipole - dipole interaction 3. nonpolar covalent bond. London Forces

How many torr are there in 1.56 atm?

1..185 torr - round up to 1,190 torr

Blood pressures are expressed in millimeters of mercury. What would be the blood pressure in atmospheres if a patient's systolic blood pressure is 120 mmHg and the diastolic blood pressure is 82 mmHg? (In medicine, such a blood pressure would be reported as "120/82," spoken as "one hundred twenty over eighty-two.")

120 ----------- = 0.158 atm 760 atm 82 --------- = 1.108 atm 760

Write a conversion factor to determine how many millimeters of mercury are in 9.65 atm.

9.65 atm x 760 mmhg ----------- = 7,334 mmhg 1atm

Why does a gas exert pressure?

A gas exerts pressure as its particles rebound off the walls of its container.

polar molecule

A molecule with a net unequal distribution of electrons in its covalent bonds

Other common units of pressure are the atmosphere (atm)

A unit of pressure equal to the average atmospheric pressure at sea level.

Why does the kinetic theory of gases allow us to presume that all gases will show similar behavior?

According to the kinetic theory of gases, all gases will show similar behavior because a gas that follows these statements perfectly is called an ideal gas. Most gases show slight deviations from these statements and are called real gases.

Are substances with strong intermolecular interactions likely to be solids at higher or lower temperatures? Explain.

At higher temperatures, their intermolecular interactions are strong enough to hold the particles in place.

What is the kinetic theory of gases?

Gases are composed of tiny particles that are separated by large distances. Gas particles are constantly moving, experiencing collisions with other gas particles and the walls of their container. The velocity of gas particles is related to the temperature of a gas. Gas particles do not experience any force of attraction or repulsion with each other.

Charles's law is sometimes referred to as

Gay-Lussac's law, after the scientist who promoted Charles's work.)

Are substances with weak intermolecular interactions likely to be liquids at higher or lower temperatures? Explain.

If the intermolecular interactions are weak, a low temperature is all that is necessary to move a substance out of the solid phase.

What happens to the volume of a gas if its pressure is increased? Assume all other conditions remain the same.

If the pressure of a gas is increased, the volume decreases in response.

What happens to the volume of a gas if its temperature is decreased? Assume that all other conditions remain constant.

If the temperature of a gas sample is decreased, the volume decreases as well.

What happens to the pressure of a gas if its volume is increased? Assume all other conditions remain the same.

If the volume of gas is increased , the pressure of the gas decreases

State two differences between the solid and liquid states.

In solid state ; relative particle positions are : in contact but not fixed. Liquid state ; the relative particle are : n contact and fixed in place In solid ; relative intermolecular interaction strength are strong In liquid ' relative intermolecular interaction is moderate.

covalent network bonding

In these substances, all the atoms in a sample are covalently bonded to other atoms; in effect, the entire sample is essentially one large molecule. Many of these substances are solid over a large temperature range because it takes a lot of energy to disrupt all the covalent bonds at once. One example of a substance that shows covalent network bonding is diamond, which is a form of pure carbon. At temperatures over 3,500°C, diamond finally vaporizes into gas-phase atoms.

List these intermolecular interactions from weakest to strongest: London forces, hydrogen bonding, and ionic interactions.

London forces, hydrogen bonding, and ionic interactions

What is pressure, and what units do we use to express it?

Pressure is the force per unit area; its units can be pascals, torr, millimeters of mercury, or atmospheres.

If individual particles are in contact with each other, a substance may be in either the ______ or _______ state but probably not in the ______ state.

Solid or liquid ; gas state

ionic interactions

Substances that contain ionic interactions are relatively strongly held together, so these substances typically have high melting and boiling points. Sodium chloride is an example of a substance whose particles experience ionic interactions

pressure

The force generated by gas particles is divided by the area. Force divided by area. Pressure is a property we can measure for gas, but we typically do not consider pressure for solids or liquids. The basic unit of pressure is the newton per square meter (N/m2). The combined unit is re-defined as a pascal (Pa):

Kinetic theory of gases

The fundamental theory of the behavior of gases: • Gases are composed of tiny particles that are separated by large distances. • Gas particles are constantly moving, experiencing collisions with other gas particles and the walls of their container. • The velocity of gas particles is related to the temperature of a gas. • Gas particles do not experience any force of attraction or repulsion with each other. A gas that follows these statements perfectly is called an ideal gas. Most gases show slight deviations from these statements and are called real gases.

What phase or phases have a definite volume? What phase or phases do not have a definite volume

The states that have definite volume are : Solid and liquids. Gas state has no definite volume.

Exhaling air requires that we relax the diaphragm, which pushes against the lungs and slightly decreases the volume of the lungs.

This slightly increases the pressure of the air in the lungs, and air is forced out; we exhale.

mmHg (millimeters of mercury) ( Torr )

a unit of pressure equal to the pressure generated by a column of mercury 1 mm high. The unit millimeters of mercury is also called a torr

What type of intermolecular interaction is predominant in each substance? a. water (H2O) b. sodium sulfate (Na2SO4) c. decane (C10H22)

a. Hydrogen bond b. Ionic bond c. temporary dipole attractions?

Torr ( mmHg)

another name for millimeters of mercury, in honor of Evangelista Torricelli, inventor of the barometer in the 1600's.

dispersion forces (or London forces)

are forces between all molecules that are caused by electrons being in different places in a molecule at any one time, which sets up a temporary separation of charge that disappears almost as soon as it appears

Combined gas law

brings Boyle's and Charles's laws together to relate pressure, volume, and temperature changes of a gas sample: Because of the dependence on three quantities at the same time, it is difficult to tell in advance what will happen to one property of a gas sample as two other properties change.

For air to move in and out of the lungs, the pressure inside the lungs must change ( Boyl's Law

forcing the lungs to change volume—just as predicted by Boyle's law. The pressure change is caused by the diaphragm, a muscle that covers the bottom of the lungs. When the diaphragm moves down, it expands the size of our lungs. When this happens, the air pressure inside our lungs decreases slightly.

polar covalent bond

has an unequal sharing of electrons (δ+H - δ− F )

State two similarities between the solid and liquid states.

high density; definite volume

gas phase

in which individual particles are separated from each other by relatively large distances. Has neither a definite volume nor shape.

What are the general properties of liquids

indefinite shape. defined volume , low density and cant be compressed .

Liquid phase

individual particles are in contact but moving with respect to each other. Has a definite volume but no definite shape.

solid phase

individual particles can be thought of as in contact and held in place;has definite volume and shape.

Phase

is a certain form of matter that includes a specific set of physical properties. A form of matter that has the same physical properties throughout.

R is called the ideal gas law constant

is a proportionality constant that relates the values of pressure, volume, amount, and temperature of a gas sample.

Charles's Law Another simple gas law relates the volume of a gas to its temperature. Experiments indicate that as the temperature of a gas sample is increased

its volume increases as long as the pressure and the amount of gas remain constant.

If individual particles are moving around with respect to each other, a substance may be in either the -----or -----state but probably not in the ------ state.

liquid , gas - solid state

dipole-dipole interaction.

oppositely charged ends of different molecules will attract each other.

Ideal Gas

relates all the independent properties of a gas under any particular condition, rather than a change in conditions.

Which unit of pressure is larger—the torr or the atmosphere?

the atmosphere

Charles' law:

the gas law that relates volume and absolute temperature.

Boyle's Law is between the pressure of a gas and its volume. If the amount of gas in a sample and its temperature are kept constant,

then as the pressure of a gas is increased, the volume of the gas decreases proportionately.

What are the general properties of gases?

variable volume and shape, low density, compressible