P3

Question 1

What is matter?

Answer 1

anything that occupies space and has mass

Question 2

What are the properties of solids?

Answer 2

Rigid
Fixed shape
Fixed volume
Cannot be compressed
Strong bonds
No flow

Question 3

What are the properties of a liquid?

Answer 3

Not rigid
No fixed shape
Cannot be compressed
Weak bonds
Flow

Question 4

What are the properties of gases?

Answer 4

Not rigid
No fixed shape
No fixed volume
Can be compressed
No bonds
Flow

Question 5

What do forces between particles affect?

Answer 5

Magnitude of forces -> affect relative distance and motion of particles

Affects ability of substance to:
Change shape, volume, flow

Question 6

How do intermolecular forces and the motion of particles affect the state of matter?

Answer 6

Solids:
Molecules -> held in place via strong intermolecular force
Only vibrate in position
Distance between -> fixed -> rigid shape and fixed volume

Liquids:
Molecules -> enough energy to overcome forces, still held close together
Volume is rigid but molecules can slide past each other -> change shape and flow

Gases:
Molecules -> overcome intermolecular forces -> more energy and move randomly at high speeds
Large space between molecules -> easily compressed and expanded + easily flow

Question 7

Describe the molecular structure of a solid, liquid and gas (including energy levels)

Answer 7

Solid:
Molecules are close (high density)
Arranged in a regular pattern
Molecules vibrate in a fixed position
Low energy

Liquid:
Molecules are relatively still close together (medium density)
No regular pattern
Molecules able to slide past each other
Medium energy

Gas:
Molecules are very separated
No regular pattern
Molecules move at random and high speeds
High energy

Question 8

How does the temperature of a gas relate to the amount of pressure it exerts?

Answer 8

Gas particles gain kinetic energy as their temp increases -> molecules are more likely to hit the sides of the container

Higher temp, higher pressure

Question 9

What is absolute zero?

Answer 9

The temperature at which gas exerts no pressure (no longer moves) -273°C or 0K (k because Lord Kelvin discovered it)

Question 10

How does the temperature of a solid liquid or gas relate to the motion of the particles? How can this explain a change in state as a result of changing temp?

Answer 10

Heat of substance increase -> kinetic energy increase -> rise in temp

As particles move faster -> vibrations take up more space -> expansion in distance -> change in states

Question 11

Describe pressure caused by gas in term of the motion of molecules

Answer 11

Gas molecules are constantly and randomly moving -> collide with things like: walls of contain and other molecules

Pressure is caused by collisions with the walls of the container
Collisions produce force at right angle to the walls -> gas at high pressure exert greater force

Higher pressure -> higher force exerted/unit area

Question 12

What is Brownian motion? How was it discovered and what did it show?

Answer 12

Brownian motion-> the random movement of particles in a liquid/gas produced by large numbers of collisions with smaller particles (too small to see)

Scottish scientist Robert Brown first described the random motion of pollen grains in water, which he saw under a microscope

Later found to show substance are made of particles that are constantly moving

Question 13

What are three types of thermometers?

Answer 13

Hot wire
Mercury
Color change

Question 14

How are celcius scale thermometers calibrated?

Answer 14

By putting in freezing (0°C) then boiling water (100°C), marking changes in temp

Question 15

How do thermometers work?

Answer 15

Most liquids expand when heated -> used in thermometers filled with alcohol and mercury

Question 16

How are thermometers engineered to measure temperature?

Answer 16

Sensitivity:
Narrower tube -> more liquid moves -> more sensitive to change in temp
Alcohol expands more than mercury -> mercury tube thinner

Range:
Mercury -> -39°C - 356°C (bigger range)
Alcohol -> -115°C - 78°C

Responsiveness:
Thermometers with thick glass or large bulb -> responds less quickly

Question 17

What changes when matter changes state?

Answer 17

The amount of energy it has

Question 18

Define melting

Answer 18

Melting happens when a solid turns into a liquid

Question 19

Define freezing

Answer 19

Occurs when a liquid turns into a solid

Question 20

Define boiling

Answer 20

Occurs when a liquid turns into a gas
Also called evaporating

Question 21

Define condensing

Answer 21

Occurs when a gas becomes a liquid

Question 22

Why does the substance not change temp when changing state?

Answer 22

Although energy is transferred away from thermal energy store, heat is used to break intramolecular forces instead of rising temps

Question 23

What is internal energy?

Answer 23

total energy stored inside a system by the particles that make up the system due to their motion and position

Kinetic energy + potential energy = internal energy

Question 24

Explain boiling+condensation in terms of energy transfer

Answer 24

Liquid water heated by adding thermal energy -> temp rising until boiling point, doesn’t get hotter (internal energy doesn’t change) -> added thermal energy used to overcome intermolecular forces -> forces overcome, water becomes vapor (evaporation)

Repeated backwards for condensation (cooling)

Question 25

Explain melting and freezing in terms of energy transfer

Answer 25

Solid heated (adding thermal energy) -> melting point (internal energy is not changed) -> added thermal energy overcomes intermolecular forces -> forces overcome -> solid becomes liquid Process goes backwards for freezing

Question 26

Define melting point

Answer 26

Melting point -> temp at which its solid and liquid phases are balanced

Question 27

Define boiling point

Answer 27

The temp at which a substance changes state from liquid to gas

Question 28

What is the difference between evaporation and boiling?

Answer 28

Evaporation -> on the surface of the liquid Any temp Boiling -> within the liquid (change of state all throughout the liquid (bubbles)) Only happens at boiling point

Question 29

Describe condensation in terms of energy transfer

Answer 29

Gas loses heat energy -> lose kinetic energy and move more slowly -> don’t have enough energy to overcome intermolecular forces -> particles get closer together -> only have enough energy to slide -> liquid REMEMBER -> doesn’t change TEMPPPP

Question 30

Describe solidification in terms of energy transfer

Answer 30

Liquid lost heat energy -> lose kinetic energy -> move slower, no enough energy to overcome forces -> particles get closer -> only enough energy to vibrate -> solid

Question 31

Explain evaporation in terms of more energetic molecules escaping

Answer 31

Molecules in liquid -> range of energies (average energy is temp) Evaporation -> more energetic molecules moving near surface have enough energy to escape Average (heat) energy reduced -> Liquid cooled by evaporation

Question 32

How do temp, surface area and draught influence evaporation?

Answer 32

Increased temp -> increased evaporation: More energy -> more likely to overcome forces Increased surface area -> increased evaporation: Only escape at surface -> more surface, more evaporation Increased air movement/draught -> increased evaporation: Air movement carries away water vapor -> new air, more evaporation

Question 33

How does a change of temp at a constant volume effect the pressure of a gas?

Answer 33

Average speed of molecules increases as temp increase Increased temp -> increased kinetic energy in same amount of space -> collide with walls more often -> increase pressure Increased temp -> increased pressure

Question 34

How does a change of volume at a constant temp effect the pressure of a gas?

Answer 34

Compressed -> decreased volume, increased pressure Expanded -> increased volume, decreased pressure

Question 35

How does a change in pressure cause a change in volume? (Balloon but say like DA MOOOOON)

Answer 35

Vacuum pump used to remove air Gas compressed (deflated) -> molecules hit walls of container more -> higher pressure Absence of gas -> less pressure -> volume of ex. Balloon increases

Question 36

What happens to materials when heated? Why?

Answer 36

They expand Molecules move/vibrate faster -> knock into each other and push apart -> space taken up increases

Question 37

What state of matter tends to expand the most when heated? Why?

Answer 37

Gas-> expand most High energy molecules have enough energy to completely overcome forces Liquid-> expand moderately Molecules have enough energy to overcome forces Solid-> expand least Low energy molecules cannot overcome forces

Question 38

What is an everyday use of thermal expansion?

Answer 38

Thermometers rely on expansion of liquids Temp activated switched work with a bimetallic strip

Question 39

How does a temp activated switch work?

Answer 39

bimetallic strip -> 2 metals that expand at different rates, bending at predicable amounts at a given temp Low expansion metal + high expansion metal -> as it is heated the high expansion metal expands more and bends

Question 40

What are some bad consequences of thermal expansion?

Answer 40

Metal railway tracks, road surfaces and bridges -> Buckling, space of expansion in cracks or spaces

Question 41

What physical properties can change with temp?

Answer 41

The volume/density The electrical resistance

Question 42

What is important to understand linearity?

Answer 42

Most often, there is an assumption the properties change linearly/ at a steady rate Can be useful for data and relationships -> but important to know that it can be nonlinear

Question 43

Describe the structure of a thermocouple

Answer 43

2 different types of wire attached to each other Joint of wires heated -> voltage is created between the wires Increased temp -> increased voltage

Question 44

Why is a thermocouple more preferable for measuring high temps and those that change rapidly?

Answer 44

Not as sensitive and liquid in glass thermometer -> but metals have higher melting point -> can be used to measure higher temps Also responsive the rapidly changing temps

Question 45

What is a fixed point?

Answer 45

A temp where an easily identifiable change occurs (ex: melting or boiling points)

Question 46

Why is it important to identify fixed points when building a thermometer?

Answer 46

Fixed points allow you to know temp without measuring 2 fixed points used: Lower -> melting point (high on a resistance:temp graph) Upper -> boiling temp (lower on a resistance:temp graph) Once a property has been measured at 2 fixed points -> figure out at other temps

Question 47

How does the structure of liquid in glass thermometers relate to sensitivity, range and linearity?

Answer 47

Sensitivity: Liquid expands more Thin glass capillary tube -> heat transfers better Larger glass build -> more liquid -> larger change Narrow tube -> small change in volume results in liquid moving a larger distance Linearity: Liquid chosen expands linearly Range: Low freezing and high boiling point

Question 48

Describe the structure of a thermometer

Answer 48

Thin glass capillary tube Contains liquid -> expands with temp Glass bulb -> contain liquid which when heated goes up the tube Scale on the side -> allows temp to be measured

Question 49

What is conduction?

Answer 49

Particles that are close transfer heat energy as they vibrate

Question 50

What are some good thermal conductors?

Answer 50

Metal pan or ceramic tea cup

Question 51

What are some bad heat conductors (and what is their alternative name)?

Answer 51

Insulators Woollen blanket or layers of cardboard

Question 52

Why are metals such good conductors?

Answer 52

Metals have free electrons which can move with heat very easily When a metal is heated the electrons gain kinetic energy and move quickly

Question 53

Explain (procedure and explaination) an experiment: Comparing conduction in tiles and textiles

Answer 53

In the same room (must have tiled floor) but a textile (must be thick) But stay are a few hours to ensure thermal equilibrium Stand with bare feet, one foot one each Observe apparent temp of 2 materials through feet Feel like tiles are cold while rug is warm -> but they are the same temp Explanation: Tiles are good conductors Foot touches tiles -> heat transfer away -> feels cold Textiles are good insulators Foot touches textile -> heat not transfer -> feels warm (in comparison)

Question 54

Explain (procedure and explanation) an experiment: Comparing conduction in wood and metal

Answer 54

Cylindrical rod of half wood half metal wrapped in paper Gentle flame with rod above the tip of the flame heat paper at the join of the 2 materials (turn rod) Stop when paper is clearly discolored Observe burn pattern on paper -> paper touched metal -> un damaged -> paper touch wood -> charred Explanation: Metal -> good conductor Paper touched metal -> heat transferred to metal -> paper prevented from getting hot Wood -> good insulator Paper touched wood -> heat not transferred -> paper burned

Question 55

Explain (procedure and explanation) an experiment: Demonstrating different rates of thermal conduction in metals

Answer 55

Stand holding a conduction ring ‘Cross’ of four metals stuck to ring -> meeting point is at the center of the circle Ball bearing at the ends+underside of each metal using wax Bunsen burner under the center Center heated with a candle/bunsen burner Metals heated -> wax melt -> ball bearing dropped Amount of time shows their relative thermal conductivity

Question 56

Explain conduction in terms of energy transfers and vibrations

Answer 56

Conduction -> main form of thermal energy transfer in solids Conduction occurs when 2 solids of different temps come into contact -> Thermal energy transferred When substance heated -> atoms/ions vibrate more -> atoms of hotter material bumps into atoms of cooler material -> energy transferred -> internal energy transferred until equilibrium is reached

Question 57

What does convection rely on? Why does this affect what state of matter it occurs most in?

Answer 57

Convection uses density of the substance Main way heat travels through liquids and gases -> atoms can flow (cannot happen in solids)

Question 58

What is/how does a convection current work?

Answer 58

Liquid heated -> molecules pushed apart -> expansion -> less dense -> hot substance rises because it is les dense -> eventually it cools -> contracts -> sinks back down Remember: convections currents can be cause by heating or cooling

Question 59

Describe an experiment designed to show convection in liquids/gases

Answer 59

Beaker of water with few crystals of potassium permanganate When water is heated on bottom -> potassium permanganate dissolves in heated water Rises with the heated water, showing convection current

Question 60

What are properties of (thermal) radiation?

Answer 60

Doesn’t require a medium to travel thought Part of em Spectrum -> infrared Only way heat travels through a vacuum -> like space Color of object will affect how good it is at emitting+absorbing radiation

Question 61

How does color and texture affect the emission/absorption/reflection of radiation?

Answer 61

Color: Black -> good absorber, good emitter Darker colors -> reasonable absorber, reasonable emitter White -> poor absorber, poor emitter Texture: Shiny -> very poor absorber (reflects), very poor emitter Emits little so it takes longer to cool

Question 62

Describe an experiment that can investigate the properties of good/bad emitters/absorbers (including variables, equipment, experiment, analysis, results)

Answer 62

Variables: Independent -> color Dependent-> temp Control -> flask, amount of water, starting temp of water, time Equipment: kettle (boil water) 4 thermometer (measure temp) Flask (one gray, black, white silver) Heatproof mat (protect surface and prevent heat loss) Stopwatch (record time) Experiment: set up 4 flask (identical), all painted different colors Fill flask with hot water (same amount and temp) Cover top and add thermometer Note starting temp, measure temp at regular intervals for 10min (in a table) Analysis: Intensity of radiation depends on temp, surface area, color Most heat lost via conduction and convection -> but doesn’t matter because the amount will be the same for all flask To compare heat loss-> graph (temp against time) with curve of best fit Results: Black -> fastest -> good at both Dull gray -> 2nd fastest -> reasonable at both White -> 2nd slowest - >poor at both Silver -> slowest -> very poor at both

Question 63

Pt.2 Describe an experiment that can investigate the properties of good/bad emitters/absorbers (possible errors, safety considerations)

Answer 63

Systemic errors: Hard to ensure that water in each flask is the same temp -> cools quickly Digital thermometer can be used for most accurate reading Random errors: Hole for thermometer isn’t too big Repeated readings Read thermometer at eye level -> no parallax error Safety: Keep away from electrical equipment Don’t touch hot water Do not overfill kettle Avoid knocking over equipment Carry out while standing -> faster reaction

Question 64

Explain and give an example of an everyday application of (+consequences): Conduction

Answer 64

Conduction: main form of thermal energy transfer in solids Heated -> atoms vibrate -> collide -> transfer energy Mention metal -> usually conduction Metal good conductor Non metal bad conductor Hot coffee transfers heat to cool mug -> heat up mug -> mug become hot -> heat transferred to cold hand -> warm hands

Question 65

Explain and give an example of an everyday application of (+consequences): Convection

Answer 65

Convection: main means of thermal energy transfer in liquids and gases Heated -> expand -> less dense -> rise -> cools -> falls If heat source at bottom/cooling at top -> usually convection Steam rises away from coffee

Question 66

Explain and give an example of an everyday application of (+consequences): Of all three types of thermal energy transfer at same time

Answer 66

In irl situations -> usually more that one form at once Conduction: heat lost from cup via contact Convection: steam rises away from tea (air above tea) Radiation: emitted from surface of any hot object, ex: cup of tea Heat loss until thermal equilibrium

Question 67

How is a rise in temp related to the internal energy?

Answer 67

Internal energy is all energy stored in the system (kinetic and potential) Heat -> increased kinetic energy -> increase internal energy

Question 68

What factors determine how much the temp of a system will increase?

Answer 68

Mass of substance Type of material Amount of thermal energy transferred

Question 69

What is specific heat capacity?

Answer 69

The amount of energy required to raise the temp of 1kg of a substance by 1°C Also called c

Question 70

What does low and high c mean?

Answer 70

Low: Heats up and cools down quick (takes less energy to change temp) Ex: copper High: Heats and cools slowly (takes more energy to change temp) Ex: water

Question 71

How can specific heat capacity be calculated?

Answer 71

ΔE=mcΔθ ΔE = change in thermal energy, in joules (J) m = mass, in kilograms (kg) c = specific heat capacity, in joules per kilogram per degree Celsius (J/kg °C) Δθ = change in temperature, in degrees Celsius (°C)

Question 72

What is thermal equilibrium?

Answer 72

Object absorbs thermal radiation -> hotter -> emit more radiation Temp of body increase when body absorbs more than it emits Temp of body decreases when body absorbs less than it emits Eventually -> reach a point of constant temp where absorbing and emitting rates are the same

Question 73

What is boyles law?

Answer 73

Pressure is inversely proportional to volume of a(n ideal) gas

Question 74

What is the equation for the relationship between pressure and volume for gas at a constant temp?

Answer 74

P1V1=P2V2 X1 -> initial X2-> final Note: orignal units can be used, but must remain the same