Grade 7 Chemistry Slideshow presentation

1. Y.H.I.M.S – Mr. Coats
Reference: Science Explorer
Motion, Forces & Energy
Chapter 6, Sections 1&2

2.  There are many
different forms of
energy
◦ Light, sound, chemical,
heat..etc.
 Which of these four
types of energy do
you think represents
thermal energy?

3.  Objects are made up of
particles
 Always moving
 Temperature measures the
kinetic energy (movement)
of these particles.
 As temperature increases
the particles move ________
and their kinetic energy
_____________.
faster
increases

4.  Different units:
◦ Celsius (oC),
◦ Fahrenheit (oF),
◦ Kelvin (K)
 The coldest temperature?
 0K or –273 oC – ABSOLUTE ZERO

5.  alcohol inside a glass tube.
 Kinetic Energy of alcohol
particles match what you are
measuring.
low high
slower faster
increase decrease

6.  Total amount of heat energy an object has
 Different objects can have the same
temperature but different amount of thermal
energy.
 Is it possible for cold water to have more
thermal energy than hot water? How?

7. ◦ The large coffee because it has more particles
◦ The coffee at the higher temperature because even
though it has the same number of particles they
have more kinetic energy

8.  Energy transferred
between objects
◦ Warmer colder
 Measured in Joules

10.  Specific Heat Capacity - amount of
energy needed to raise the temperature
of 1kg of material by 1K.
 The units for specific heat are (J/kg*K)

13. Specific Heat= Change in Energy
Mass x Change in Temperature
J/kg*K
J
kg K
Change in Energy = Specific Heat x Mass x Change in Temp.

14.  209,000J of energy is required to heat 5kg of
water by 10K. What is the specific heat
capacity of water?
◦ Change in energy = 209,000J
◦ Change in temperature = 10K ; mass = 5kg
Specific Heat = Change in Energy
Mass Change in Temperature
Specific Heat = 209,000J / 5kg x 10K
= 4,180 J/kg*K
x

16.  Two objects touch each other and
heat is transferred.
 Heat is transferred from the _______
object to the _______ object.
warmer
colder

17.  The movement of heat by means of
currents in either air or water.

18.  Transfer of energy by electromagnetic
waves.
 It does not need matter to transfer heat
from one object to another - No gas or
liquid required

19.  Convection
◦ http://www.youtube.com/watch?v=5pG-tkbQgMo
 Radiation
◦ http://www.youtube.com/watch?v=wz6wzOtv6rs

22.  Conductors
 A conductor is a material which conducts
heat well.
◦ We would expect a conductor to have a ________
specific heat capacity and require ___________
energy to increase temperature.
low
less

23.  Insulators
 An Insulator is a material which does not
conduct heat well.
◦ We would expect an insulator to have a _________
specific heat capacity and require ___________
energy to increase temperature.
high
more

24. Conductor Insulator

25. Y.H.I.M.S – Mr. P. Coats
Reference: Science Explorer
Chemical Building Blocks,
Chapter 2, Section 1

26. States of Matter
What are the states of matter?

27.  Difference in arrangement and movement
 Temperature increases – particles move
 Identical on the Chemical level
◦ E.g. Water.

28. 1. Closely packed particles
2. Regular Arrangement
3. Definite Shape
4. Definite Volume (can’t
compress)
5. Least amount of Energy
ICE

30. 1. Closely packed particles
2. Not Regular Arrangement
3. No Definite Shape
4. Definite Volume (Not
Compressible)
5. More Energy than Solid
WATER

32. 1. Loosely packed particles
2. Not Regular
Arrangement
3. No definite Shape
4. No definite Volume
(Easily Compressed)
5. High Energy
STEAM

33. 1. Gases at very high
temperature
2. Electrically charged
3. Similar properties to gas
4. Highest Energy
5. Most matter in the
universe is Plasma

34.  Solid to Liquid –
 Temperature at which it changes -
 .
 Liquid to Solid -
 Temperature at which it changes –
 .
Freezing
Melting
Melting point
Freezing point

36. Liquid to Gas: ________________
 Evaporation – Vaporization occurs at
surface of liquid
 Boiling – Vaporization occurs
throughout liquid
 Temperature at which a liquid will
turn into a gas: _________________
 What is the B.P. of water?
Vaporization
Boiling Point
100oC

37.  Gas to Liquid: _ ____________
 What happens when you have
cold Coca-Cola on a hot day?
 Condensation (water) appears
 on surface of the glass.
Condensation

38. • Solid to Gas: ______________
• No liquid phase
• Gas to Solid: _____________
• No liquid phase
Deposition
Sublimation

40. 1. Solid  Liquid
2. Liquid  Solid
3. Liquid  Gas
4. Gas  Liquid
5. Solid  Gas
6. Gas  Solid
Vaporization
Condensation
Sublimation
Freezing
Melting
Deposition

41.  You are cooking some
ramen on your stove and
you leave two spoons in
the boiling water. One is
wooden and the other is
steel. After one minute
which spoon do you
believe will be hot and
which only warm. Why?
◦ The steel spoon will be hot.
It requires less energy to
increase temperature
Temperature(Co)
Time (min)
Gold
(50g)
Nickel
(50g)
0
0
100
10
1 4.15
Which substance requires more
energy to increase temperature?
Nickel requires more than 4 times more
energy than gold.

42. Temperature(Co)
Time (min)
Gold
(50g)
Nickel
(50g)
0
0
100
101 4.15
Q: Which requires more energy to
increase temperature? Gold or Nickel?
A: Nickel: needs more than 4
times more energy than gold!

43.  When ice is left out
at room temperature
does it all melt
instantly? Why?
 No, it takes a long
time to melt. The ice
takes time to absorb
heat energy from
the air and melt.
 Which is correct A or
B?
◦ B
Time (min)
Water (A)
Water (B)
-20
0
80
10
Temperature(Co)
0

44. Time (min)0
110
10
Temperature(Co)
0
78
100

45. Y.H.I.M.S – Mr. P Coats
Reference: Science Explorer
Chemical Building Blocks,
Chapter 2, Section 3

46.  Can we measure the quantity of gas by simply
measuring volume like a liquid or solid?
◦ No. In order to measure the quantity of a gas we
need 3 things.
1. Volume – Units can be m3 or L.
2. Temperature – At higher temperature gases
move faster and the same quantity of gas
will take up more volume.
3. Pressure

47.  Pressure = Force (N)/Area (m2)
◦ Units of pressure is pascals
(Pa) or kilopascals (kPa)
◦ How many pascals in a
kilopascal?
◦ 1,000
 Higher pressure is caused by a
greater concentration of gas
particles in a given area.
 Gravity holds our atmosphere
(gas) to the Earth at an average
pressure of 101.3 kPa at sea
level.

48.  You climb to the top
of Mt. Everest and
prepare to eat some
ramen. Does water
still boil at 1000C?
Why?
 No. It will boil at a
lower temperature
(690C) because there is
less pressure to keep
water a liquid.

51.  Initial Pressure, Volume (P1 ,V1)
 When temperature # of gas
molecules stay the same:
◦ If Volume decreases, what will
happen to the pressure?
 Pressure and Volume vary
inversely (opposite)!
◦ If one value goes up, the other goes
down!
P1 x V1 = P2 x V2
Increases!

52.  Initial Volume, Temperature (V1 ,T1)
 Pressure, # Molecules stay the same
 If Temperature increases, what will
happen to the Volume?
 More energy, more movement more
volume!
 *Absolute Temperature = Kelvin Scale
◦ 0 0C = 273 K
 Temperature and Volume are directly
proportional!
◦ Both go up and down together!
Increases!
V1 = V2
T1 T2

53.  Switching to Kelvins: ADD 273 (+273)
• Switching to Celsius: SUBTRACT 273 (-273)
• Kelvin IS NEVER BELOW 0!!
0 0C = 0 + 273 =
273 K20 0C = 20 + 273 =
293 K75 0C = 75 + 273 =
348 K
373 K = 373 - 273 =
100 0C320 K = 320 - 273 = 47
0C150 K = 150 - 273 = -
123 0C

54.  Boyle’s Law:
 Pressure is initially (starts
at) 3 ATM, and volume is
initially 1 L
 Volume changes to 4L,
New Pressure?
 Charles’ Law:
 Temperature is initially
(starts at) 40 0C, Volume is
520 L
 Temperature decreases to
15C, New Volume?
V1 = V2
T1 T2
P1 x V1 = P2 x V2
(40 0C = 313 K)
(15 0C = 288 K)
0.75 ATM
478.5 L