2 myp Chemistry states and energy

M4 Chemistry Matter II: M4 Chemistry Matter II: State and EnergyState and Energy

M4 Chemistry Matter: State and Energy Slide 2 of 33

Learning objectivesLearning objectives

• Concepts:

– Kinetic theory, solid, liquid, gas, sublimation, melting, vaporization, condensation, deposition, freezing (fusion)

– Vibration, rotation, translation, energy, force, kinetic energy, potential energy, temperature

– Electromagnetic (electrostatic) force

• Skills:

– All energy is an atom can be classified as kinetic or potential.

– State that matter is always in constant motion (kinetic theory).

– Distinguish between the kinetic forms of energy that atoms/molecules contain: translation, rotation, and vibration.

– Explain the relationship between the motion of atoms and the temperature of atoms.


Learning objectivesLearning objectives

– Describe that the potential energy between atoms in arrays or between molecules condensed forms of matter is due to electrical forces (electromagnetic or electrostatic forces)

– Explain that electromagnetic or electrostatic forces are much stronger than gravitational forces and explain why you cannot put your hand through a wall.

– State the difference between the macroscopic, microscopic, and sub-microscopic views of mater.

– Explain that macroscopic matter is made up of sub-microscopic particles packed together in large arrays.


Kinetic TheoryKinetic Theory

• The three different states of matter and the way in which they behave is derived from and is explained by the kinetic theory.

The main ideas behind the theory are:

– All matter is made up of tiny particles, sub-microcopic particles, in motion all the time.

– The particles are in motion at all time and changes with temperature—higher the temperature the faster their speed on average.

– The lighter particles mover faster than heavier ones at the same temperature.

• The above three statements of the kinetic theory is used in Chemistry to explain how the arrangement of particles in matter relate to the properties of the three states of matter.


Characteristics of Solid State: Solid Characteristics of Solid State: Solid ElementsElements

Solid atomic element

• Kinetic theory says that the particles in a solid substance attract one another very strongly and hold them close together.

Therefore atoms and molecules in a solid have regular arrangements.

Atoms/molecules fixed in position, the particles therefore do not have as much freedom of movement.

All they are able to do is vibrate in place, without changing position.

Solid diatomic molecular element


Characteristics of Solid State: Solid Characteristics of Solid State: Solid ElementsElements

• That is why solids at the macroscopic level have fixed shape

– Example of solid atomic elements: sodium, carbon, sulfur, phosphorus.

– Examples of solid diatomic elements: iodine.


Characteristics of Liquid State: Liquid Characteristics of Liquid State: Liquid ElementsElements

liquid atomic element

liquid diatomic molecular element

• Kinetic theory says that the particles in a liquid are still close together and attracted each other but not as strongly as in a solid.

As the forces are weaker, the particles are able to move around more freely than in a solid, and as they do they collide with one another.

– Atoms/molecules can vibrate as well as rotate and translate.

• Since, atoms/molecules in a liquid aren’t fixed in position a liquid takes the shape of the container and can flow as well.


Characteristics of Liquid State: Liquid Characteristics of Liquid State: Liquid ElementsElements

– Example of liquid atomic elements: mercury.

– Example of liquid diatomic elements: bromine.


Characteristics of Gaseous State: Gaseous Characteristics of Gaseous State: Gaseous ElementsElements

• Kinetic theory says that the particles in a gas far apart and very weakly attracted to each other.

So weakly as a matter of fact that the particles have complete freedom of movement and so move randomly at very high speeds in any and all direction colliding with each other and the container walls.

– Atoms/molecules are in random motion, vibrating, rotating and translating at all times.

Gaseous atomic element

Gaseous molecular element


Characteristics of Gaseous State: Gaseous Characteristics of Gaseous State: Gaseous ElementsElements

• Consequently a gas takes up the shape of the container as well.

– Example of gases atomic elements: argon, neon, helium.

– Example of gaseous diatomic elements: hydrogen, nitrogen, oxygen, chlorine.


CompoundsCompounds

Gaseous Molecular compound

Another gaseous molecular compound

Solid compound Liquid Molecular compound


Element, compound and mixtureElement, compound and mixture

Mixture of two solid elements

e.g. Alloys, sand and salt

Mixture of two gaseous elements

e.g. argon and helium

Mixture of two gaseous elements one of which is molecular

Mixture of an element and compound Mixture of two gaseous compounds

e.g. carbon dioxide and carbon monoxide


Compound and mixtureCompound and mixture

• A compound is different from a mixture in that the atoms in a compound are chemically bonded together, and that’s why the physical and chemical properties of the compound is markedly different from the elements from which it is made.


Characteristics of the Three States of MatterCharacteristics of the Three States of Matter


Physical State and EnergyPhysical State and Energy• The gaseous state of a substance have more energy than the liquid

state, which in turn has more energy than the solid state.

Let’s take steam for instance.

To convert steam at 100C to water, it has to be cooled indicating that energy has to be taken out of it to change it to water.

Similar, to convert water to ice, it also has to be cooled, again indicating that it has more energy than ice.


Phase ChangePhase Change

• Conversely, ice has to be heated to convert it to water and water has to be heated to change it to steam. Phase change, change from one physical state to another, takes place due to changes in the energy content of a substance.

Changing the temperature changes the energy of a substance.

Increasing the temperature of a substance increases the motion of the particles in the substance, thus increasing the kinetic energy of the particles and therefore the total energy of the substance. Additionally, continuing to heat water at 100C (the boiling temperature) causes the water molecules to escape from the container and change in to gaseous molecules of water also at 100C.


Physical State and EnergyPhysical State and Energy

• The energy provided here is able to force the molecules of water to separate.

– Phase change at a constant temperature thus involves causing the particles to be farther apart and thus contain more potential energy.

• Kinetic energy is energy due to motion of the object.

Potential energy is energy due to the position of an object relative to another or other objects.

– Gaseous water molecules at 120C have higher kinetic energy than gaseous water molecules at 100C, but the same potential energy.

– Gaseous water molecules at 100C have the same kinetic energy as (liquid) water molecules at 100C because they are both at the same temperature.

– Similarly, water molecules at 80C have less kinetic energy than one at 100C, but the same potential energy.


Physical State and EnergyPhysical State and Energy

• In general when a solid is heated, the particles in it vibrate more vigorously until the temperature reached the melting point.

When it is heated further, the solid starts to melt at the constant temperature (of melting point).

During the time that it melts, the particles gain potential energy.

Further heating of the liquid increase the vibrational, rotational and translational motion of the particles in the liquid.

At the boiling point, the liquid starts changing into the gas phase.

The heat that converts the liquid into gas at the constant temperature of the boiling point increases the potential energy of the particles.

Further heating of the gaseous particles increases the translational motion of the gaseous particles considerably.


Heating curveHeating curve

t1 t2 t3 t4

Time / min

t0

TEMPERATURE

/K

mp

bp

in p.e.

in p.e.

in k.e.

in k.e.

in k.e.


Electromagnetic ForceElectromagnetic Force

• The origin of kinetic and potential energy in substances is the force of attraction between the particles arising from the charges in the sub-microscopic particles. Since atoms and molecules are made up of negative electrons and positive protons, they attract each other. Attraction between charged particles, attraction originating from the interaction of oppositely charged particles, is referred to as electromagnetic or electrostatic force of attraction. Electromagnetic forces between and within sub-microscopic particle (atom, molecules and ion) are extremely strong forces. It is for that very reason that the most our enduring of energy sources is the sun the reaction in which is electromagnetic in nature.


Electromagnetic ForceElectromagnetic Force

• It is for that very reason that the most destructive of the weapons created by man the atom bomb also relies on electromagnetic forces. Nuclear power plants depend on elements (Uranium) which generates energy due to processes taking place in its nuclei also involving electromagnetic forces.


Terms Associated with State ChangesTerms Associated with State Changes


Practice QuestionsPractice Questions

• 1. The water from the natural springs in Bath is hot. The Romans made use of this water in the famous baths.

Artist’s drawing of the bath at Aquae Sulis (Bath), Britain. Built by the Romans, 1st century AD.

• The water is heated by rocks deep underground. The rocks are hot because they contain radioisotopes. When the radioisotopes split up they give out energy. At a depth of 1000 metres the rocks are hot enough to make water boil.



• (a) (i) Complete the diagram below to show how the particles might be arranged in a solid such as rock. Use circles like the one already drawn for you to represent the particles in the solid.



(ii) Describe the movement of the particles in the solid rock. [1]

(iii) How does the energy released from the radioisotopes affect the movement of the particles in the solid rock?

[1]

• (b) The water from the hot springs would evaporate faster than cold water. Explain, as fully as you can, in terms of the water particles and the forces between them why this is so.

[4]



• 2. The pie chart shows the amount of tin and lead in an alloy.

t in le ad(a) Use the pie chart to work out the

mass of lead needed to make 10g of this alloy.

Mass of lead needed .................. g [1]

(b) When this alloy is heated it melts to form a liquid. Some of the alloy also evaporates to form a gas.The three diagrams below show how the atoms in the alloy are arranged in the three states solid, liquid and gas.

Label each diagram as solid, liquid or gas.



•....................... ..................... .........................[2]

(c) Explain why liquid alloy can be poured but solid alloy cannot be poured. [2]



• 3. Bottled water is sold throughout the world.

P la stic b o ttle

A ir

W ate rW ate r

H 0

P a rt A rr an g em e n to f p a r tic les

2

(a) Draw a line to join each labelled part to the arrangement of its particles. [2] (b) Use one of the words in the box to complete the sentence.

ice liquid steam vapour

• The bottle of water was put into a freezer to cool it down. It was left too long, so the water changed to .............................. . [1]


Practice Questions: Multiple ChoicePractice Questions: Multiple Choice

• 1) Which states of matter are significantly compressible?

A) gases only B) liquids only

C) solids only D) liquids and gases E) solids and liquids

• 2) The law of constant composition says __________.

A) that the composition of a compound is always the same

B) that all substances have the same composition

C) that the composition of an element is always the same

D) that the composition of a homogeneous mixture is always the same

E) that the composition of a heterogeneous mixture is always the same

• 3) Which of the following is an illustration of the law of constant composition?

A) Water boils at 100C at 1 atm pressure.

B) Water is 11% hydrogen and 89% oxygen by mass.

C) Water can be separated into other substances by a chemical process.

D) Water and salt have different boiling points.

E) Water is a compound.



• 4) Gases and liquids share the property of __________.

A) compressibility B) definite volume

C) incompressibility D) indefinite shape E) definite shape

• 5) "Absolute zero" refers to __________.

A) 0 Kelvin B) 0 Fahrenheit

C) 0 Celsius D) C + 9/5(F - 32) E) 273.15C

• 6) For a given substance such as water,

A) the liquid state has more energy than either the gaseous or solid state

B) the solid state has more energy than either the gaseous or liquid state

C) the gaseous state has more energy than either the solid or liquid state

D) the liquid state has the least energy of the three states

E) the solid state does not have any energy



• 7) An object moving at a high speed always has

A) more potential energy than one at rest

B) less potential energy than one at rest

C) more kinetic energy than one at rest

D) less kinetic energy than one at rest

E) equal potential and kinetic energy as one at rest

8) Water at 70C has ________________ one at 90C.

A) less potential energy than B) more kinetic energy than

C) more potential energy than D) less total energy than

E) the same total energy as



• 9. Ice at 0C and ice cold water also at 0C have

A) particles that have different type of motion

B) particles that on average have same amount of potential energy

C) particles that are absolutely still

D) particles that are of different sizes

E) particles that are different

• 10. Steam at 100C

A) will have the same potential energy as water at water at 100C

B) will scald more badly than water at 100C

C) will need heat to condense to water

D) will consist of regularly arranged water molecules

E) will consist of molecules moving very very slowly



• 11. Particles in alcohol at 50C on average ___________ water at 50C

A) be moving at the same speed as those in

B) will have the same kinetic energy as those in

C) will have the same potential energy as those in

D) will have fewer freedom of movement than those in

E) will have greater freedom of movement than those in

Education

2 myp Chemistry states and energy