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Physical Properties and Conversions: Density, Velocity, Temperature, and Heat, Lecture notes of Chemistry

Explanations and examples on various physical properties such as density, velocity, temperature, and heat. It covers the concepts of derived units, extensive and intensive properties, and their conversions. The document also includes examples on calculating density using mass and volume, converting units of density, and finding the mass of a wire given its diameter and density.

What you will learn

  • How is density calculated?
  • What is the difference between extensive and intensive properties?
  • How to convert the density from g/cm3 to kg/m3?

Typology: Lecture notes

2021/2022

Uploaded on 09/12/2022

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Derived units (derived from the base units)
Volume (V)1 m3= (1 m) ×(1 m) ×(1 m)
1 mL = 1 cm3= (1 cm)×(1 cm)×(1 cm) =
(10-2 m)×(10-2 m)×(10-2 m) = (10-2×10-2×10-2) m3= 10-6 m3
1 L = 1 dm3= 10-3 m31 mL= 10-3 L
Density (d)mass (m) per unit volume (V)
(d= m/V)
unit of d= (1 kg)/(1 m3) = 1 kg/m3
Velocity (v)distance (l) per unit time (t)
(v= l/t)
unit of v= (1 m)/(1 s) = 1 m/s
Extensive properties depend on sample
size (mass, volume, length, ...)
Intensive properties independent of
sample size (density, temperature, color, ...)
Example:
What is the density of an alloy in g/cm3, if
55 g of it displace 9.1 mL of water?
d= m/V= (55 g)/(9.1 mL) = 6.0 g/mL =
6.0 g/cm3
Example:
Convert the density of gold, 19.3 g/cm3, to
kg/m3.
need to convert both the numerator and
denominator gkg and cm3m3
1 kg = 103g
1 cm = 10-2 m 1 cm3= (10-2)3m3= 10-6 m3
3
3
36
3
33 10319
10
1
10
g 1
319 m
kg
.
m
cm
g
k
cm
g
.d ×=
×
×=
Example:
What is the mass in kg of a 15 ft wire made of
an alloy with d = 6.0 g/cm3if the diameter of the
wire is 0.20 in?
Plan:
Diameterradius (cm)cross-section area (cm2)
Length (cm) ×cross-section area volume (cm3)
Volume & density mass (g) mass (kg)
15 ft
0.20 in
pf3

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Derived units

(derived from the base units)

Volume (

V

)^

1 m

3

= (1 m)

×

(1 m)

×

(1 m)

1 mL = 1 cm

3

= (1 cm)

×

(1 cm)

×

(1 cm) =

m)

×

m)

×

m) = (

×

×

) m

3

m

3

1 L = 1 dm

3

m

3

1 mL= 10

L

Density (

d

mass (

m

) per unit volume (

V

d

m

/ V

unit of

d

= (1 kg)/(1 m

3

) = 1 kg/m

3

Velocity (

v

distance (

l ) per unit time (

t )

v

l

/ t

unit of

v

= (1 m)/(1 s) = 1 m/s

Extensive properties

  • depend on sample

size (mass, volume, length, ...)

Intensive properties

  • independent of

sample size (density, temperature, color, ...) Example: What is the density of an alloy in g/cm

3

, if

55 g

of it displace

9.1 mL

of water?

d

m

V

= (55 g)/(9.1 mL) = 6.0 g/mL =

6.0 g/cm

3

Example:

  • Convert the density of gold,

19.3 g/cm

3

, to

kg/m

3

need to convert both the numerator anddenominator

g

kg

and

cm

3

m

3

1 kg = 10

3

g

1 cm = 10

m

1 cm

3

3

m

3

m

3

3

3

3

6

3

3

3

10

3

19

10

1

10

g

1

3

19

kg m

.

m cm

g k

cm

g

.

d

×

= 

 × 

 ×

=

Example:

What is the mass in

kg

of a

15

ft

wire made of

an alloy with

d

= 6.0 g/cm

3

if the diameter of the

wire is

in

?

Plan: Diameter

radius (cm)

cross-section area (cm

2

)

Length (cm)

×

cross-section area

volume (cm

3

)

Volume & density

mass (g)

mass (kg)

ft

in

ft

in

(^

kg

.

g kg

cm

g .

cm .

m

cm .

cm

cm

A

l

V

cm

in

cm

.

in ft

ft

l

cm

cm

r

A

cm

in

cm

.

in

.

r

in

.

in

.

r

Radius

3

3

3

2

2

2

2

×

×

×

×

×

×

×

×

Temperature (

T

– a measure of how hot

or cold an object is relative to other objects–

T

reflects the thermal energy of the object

T

is an intensive property

Heat

– the flow of thermal energy between

objects– Heat flows from objects with higher

T

to

objects with lower

T

  • Heat is an extensive property– Heat and temperature are different

• Thermometers

  • Used to measure

T

• The

Celsius

scale

  • 0ºC

freezing point of water

  • 100ºC

boiling point of water

• The

Fahrenheit

scale

  • 0ºF

freezing point of salt/water mixture

  • 100ºF

body temperature

  • water freezes at 32ºF and boils at 212ºF

100 Celsius degrees

180 Fahrenheit degrees

(^

F C

F C

F=

F C

C+32 F

C=

C F

F-32 F

T

T

T

T