Chemistry 534 Chemistry 534 Chemistry 534 Chemistry 534 Chemistry 534 Chemistry
Chapter 9: States of Matter Name:______
Chapter Notes & Exercise: Solutions
A) Kinetic Theory & the Nature of Gases:
- molecules spread through space because of the kinetic theory; what does this theory basically say:
…tiny particles in all forms of matter are in constant motion……
- The first basic assumption of the kinetic theory is that a gas is composed of molecular or atomic particles.
- T/F: _F__ There is a force of attraction/repulsion between the particles.
- T/F: _T__The particles are hard, with little volume and very far apart.
- The second assumption states: particles in a gas move constantly in random motion….
- Finally, all particle collisions are elastic meaning that..E is transferred; total KE is constant..
- If a bottle of perfume is opened in Vancouver, B.C., in 3 hours the gas particles will be in Washington, D.C. (T/F) F Why not, if false? …strike air molecules…….
- What 2 things affect the volume of a gas? ……temperature & pressure……
B) Kinetic Energy & Temperature:
- The energy an object has because of its motion is termed …kinetic energy…
- In a collection of molecules, some have very high and very low speeds. As a result, scientists use the ……average kinetic E….. This energy is proportional to the ……T…….. of the substances. Particles of substances at the same temperature have the same ……average kinetic energy….
- What can be said of the average energies in a block of ice at 0°C and the energy in a gas filled dirigible at 0°C? ……………average kinetic energy is equivalent……..
- What is different between molecules at high temperature compared to molecules at low temperatures when compared in an energy distribution curve? ……range of KE for molecules at low T is less than the range of KE for molecules at the high T….
- What is the temperature called when the motion of molecules ceases? …absolute zero..
- What is superconductivity? ……substances having no electrical resistance at temperatures close to absolute zero…… (p.688…chemdirections)
- Diamagnetism results in what phenomena? ..Levitation.... Which means what? …a magnet placed on a superconductor remains suspended in the air since it repels the magnetic field with a force exactly equal to the force of the field….
- Why is the Kelvin scale so useful? …is a direct measure of the average kinetic energy of the particles of a substance…
C)
Pressure:
- The result of simultaneous collisions of billions upon billions of gas particles upon an object is termed …gas pressure…..
- If no gas particles are present, this is termed a …vacuum….. . Commonly used to measure atmospheric pressure is the …barometer……. .
- STP stands for …standard temperature & pressure……. Numerically, this is equivalent to… ….0°C… and a pressure of …101 kPa…..
- The inventor of the barometer was ____Evangelista Torricelli______
- Equivalences: 1 atm = _101__ kPa = __760__ mm = __76__ cm = __760_ torr
- 190 mm = __25.25__ kPa
- Why, on the top of Mt. Everest, does air pressure support a column of mercury that is only 253 mm high? ______pressure decreases with altitude______
- Today’s barometers do not contain mercury but are based on a metal diaphragm controlling a pointer. They are called _____aneroid____ barometers.
D) Avogadro’s Hypothesis:
- Avogadro’s hypothesis states that:______equal volumes of gases at the same temperature
and pressure contaion equal numbers of particles______(**imp. Concept)______
- One mole of any gas at STP occupies what volume? _____22.4 L ____
- Find the volume of a container that holds 10.0 g of CO2 at STP?
10 g X 1 mol CO2 / 44 g X 22.4 L / 1 mol = 5.09 L
- What is the volume occupied by 0.50 mol of a gas at STP?
0.50 mol X 22.4 L / 1 mol = 11.2 L
- A gas has a volume of 2.24 L at STP. How many moles of gas is this?
2.24 L X 1 mol / 22.4 L = 0.1 moles
E)
The Nature of Liquids:
- Unlike gases, the particles of liquids are held together by ___weak attractive ___ forces. These forces also reduce the __space__ between the particles. Both liquids and gases _flow__.
- Liquids are much __denser___ than gases.
- Increasing the ___pressure___ on liquids has hardly any affect on their volumes. Hence, liquids and solids are known as ___ condensed states ____ of matter.
- Particles in a liquid do not usually escape from the liquid by themselves because of the _____attractive____ forces between them.
- Properties of liquids are based on the ____disruptive___ motion of the particles and the ____attractive____ forces between the particles.
F)
Vaporization:
- The conversion of a liquid to a gas or a vapor below its boiling point is termed _____vaporization__. When this process occurs with an uncontained liquid, it is termed ____evaporation___.
- T/F: _T__ Equilibrium cannot be established in an open container when a liquid’s molecules evaporate from its surface.
- What method should be used in the laboratory to evaporate flammable liquids?
- ______use a steam bath or electric hot plate ______
- Why does heating a liquid allow it to evaporate faster? ______
______kinetic energy of its particles increases ______
- If the liquid in a closed container begins to evaporate and condense at the same rate, we say that the system is in __ equilibrium __.It is actually termed to be _dynamic equilibrium__.
- As vaporized particles collide with the walls of a sealed container, they produce what is called a ____ vapor pressure ____ above the liquid.
- T/F: _T__ A terrarium exhibits equilibrium.
- It is general knowledge that liquids, upon evaporating, create a vapor pressure. (T/F) __T__ The same can be said about solids. The general rule is that increases in temperature will _____increase___ the vapor pressure.
- Similar to a barometer is a ___manometer__ which can also be used to measure the pressure of a gas sample.
- Draw a small graph to illustrate this fact based on the temperatures (°C) and vapor pressures (kPa) for ethanol:
G) The Boiling Point of a Liquid: (read continuously going across)
- The temperature at which the vapor pressure of the liquid is just equal to the external pressure is termed the ____boiling point___. (bp) The vapor begins to escape to the atmosphere and this stage marks the onset of ____boiling__.
- Evaporation is the process that occurs only at the ___surface___ of a liquid whereas boiling occurs ___throughout____ the liquid.
- The boiling point of a liquid at a pressure of 101 kPa is called the ______normal boiling point____ .
- The boiling point of a liquid changes with ______pressure___changes.
- The boiling point will decrease with lower ___ pressure____ since the particles will need less kinetic energy to escape from the liquid.
- What is the boiling point of ethanol and its formula? _____ 78.5 °C____ and C2H5OH______.
- At about what temperature would ethanol boil in Banff where the atmospheric pressure is 89.3 kPa? ____ 75 °C____ (use graph on page 208)
- T/F: _T__ The temperature of a boiling liquid never rises above its boiling point.
- Why do pressure cookers reduce cooking time? ______at high pressure water boils well above 100 °C______.
- A pressure cooker is similar to an ____autoclave____ which is used to sterilize medical instruments.
- Usually, when solids melt, they change from an orderly pattern to a more disorderly pattern. What are substances called that flow like liquids yet are still orderly? ______liquid crystals_____
- The molecules in these substances are shaped like rods with the rods organized in 3 different ways. The __ neumatic __ substances contain rod like molecules that are parallel to each other. In ___smectic___ substances, the rods are parallel and in layers, moving back and forth with certain molecules stationary in the layer. In ___cholesteric____ crystal liquids, the moving molecules are in layers, parallel to each other in the layers but each layer is not parallel to the other layers.
- What 2 things determine the color & color changes in the crystals? __distance between layers & temperature changes____ .
- In a calculator, what types of liquid crystals are used? ___ neumatic___. The crystals, sandwiched between 2 layers of glass, are oriented to prevent light from passing through which we see as the numbers. This is due to the top layer of glass being __electrified__ causing segmentation for the numbers.
H) The Nature of Solids:
- What is the motion of molecules in a solid? _____ vibrate & rotate about fixed points____
- How are vibrations, increased temperature and kinetic energy related to the (mp) of a solid?
__disruptive vibrations overcome interactions that hold them together; kinetic energy of the of the particles increase and the solid begins to melt ______
- Why do ionic solids have high (mp)? ____held together by strong forces _____whereas ___ molecular solids____ have relatively low melting points. (T/F) __F__ Wood melts when heated.
- Most solids are ___ crystalline ____in nature. The atoms, ions or molecules are arranged in an orderly, repeating, 3-D pattern in _ a crystal_____.
- This arrangement/array is called a _____crystal lattice____.
- Crystal solids occur in _7__crystal systems depending upon the __angles__ between the faces and how many of the edges are ___equal__.
- The smallest group of particles within a crystal that retains the geometric shape of the crystal is called a _____ unit cell____. The lattice is one of fourteen types of these. The seven types of crystal systems are : 1)______cubic______2) ______tetragonal____
3) _____ orthorhombic____ 4) ____ monoclinic____ 5) _____ triclinic_____
6) _____ hexagonal ______and 7) ____ rhombohedral___.
- ___ carbon__ is an example of an element that can exist in more than one type of solid state.
- The three types are ___diamond___, ___graphite___ and ____soot___.
- Solids that lack an ordered internal structure are called ___amorphous____ such as soot, rubber, plastic and asphalt.
- Glasses are amorphous solids called ____ supercooled liquids___. They are transparent, fusion products, of inorganic materials, cooled to a solid, but not having crystallized. Glasses do not have a definite __ melting point___.
- When crystalline substances break the pieces have surface __angles___ the same as the original but glasses, being ___ amorphous___, do not.
I) Phase Changes:
- These occur when the physical state of a substance changes. What does not change when the physical change is occurring is the ___temperature___.
- An element that sublimates is ___iodine___, going from a solid to gas without going through the liquid state.
J)
Energy and Phase Changes:
- What does the number 4.19 really tell you? _4.19 J of heat raise the temp. of 1 g of H2O, 1°C
- What does the slope on a heating curve tell one? __the specific heat capacity of the substance
- The heat required to melt 1 g of a solid at its melting point is its ___heat of fusion_____.
- The amount of heat given up as 1 g of liquid changes to a solid at the melting point is called the heat of __solidification____. We likewise have the heat of vaporization and the heat of condensation.
- When a gas is heated to a very high temperature, the molecules will separate into __atoms__. Next, upon continued heating, the __electrons___ will separate from the atoms. This forms a mixture of __electrons___ and positive __ions__ formed from the __ionization___ of the atom. We now have the 4th state of matter termed _____plasma____.
- The creation of highly ionized plasmas requires a lot of __energy___ and high ___temperature_____.
- Since no known material can contain plasma at these high temperatures, scientists use strong ____magnetic field____ in a device called a ____tokamak___ to confine the plasma.
- Metal surfaces could be coated with protective coverings because of plasma’s ___corrosive___ property. Because plasma conducts_ __electricity___ and creates a ____magnetic___ field, plasma could be used to make ___plasma motors and ____electrical generators____.
- An alternative form of electricity generation could come about from MHD or ___magnetohydrodynamic power generation__. This is an expanding field of plasma ___physics___.
Review Questions: circle the best answer
1. How far can a molecule travel in the air before it collides with another molecule?
a. much less than a metre b. about a metre c. much more than a metre
2. What is the SI unit of pressure?
a. candela b. mole c. Pascal d. Newton e. Joule
3. What happens to the range of energies of the molecules in matter when the temperature is increased?
a. it becomes narrower b. it becomes broader c. it does not change
4. Which temperature scale provides a direct measure of the average kinetic energy of a substance?
a. Celsius b. Fahrenheit c. Kelvin
5. How does the atmospheric pressure at altitude below sea level compare with atmospheric pressure at sea level?
a. the atmospheric pressure below sea level is higher
b. the atmospheric pressure below sea level is lower
c. the pressures are the same
6. What is the volume occupied by 18 X 10 23 molecules of fluorine at STP?(note correction..18)
a. 22.4 L b. 44.8 L c. 56.0 L d. 67.2 L e. 78.4 L
7. What types of forces exist between particles of a liquid?
a. weak attractive forces b. strong attractive forces c. weak repulsive forces d. strong repulsive forces
8. Which of the following will evaporate fastest?
a. water at 0 degrees C b. 20 c. 40 d. all of the following evaporate at the same rate
9. What is the pressure when a liquid is boiling at its normal boiling point?
a. 0 atm b. 1 atm c. 2 atm d. 5 atm
10. If heat is added to a boiling liquid, what happens to the temperature of the liquid?
a. it increases b. it decreases c. it does not change
11. Liquid crystals are characterized by…..
a. sharp melting points b. a disorganized structure c. the ability to flow d. covalent bonding