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Lecture 1

CHEM 131 Lecture Notes - Lecture 1: Dimensional Analysis


Department
Chemistry
Course Code
CHEM 131
Professor
Ladon
Lecture
1

Page:
of 2
Chapter 1 – Gen Chemistry
Classification of matter
!Substance - matters that have a definite composition and distinct properties
! Elements – substance a single type of Atom.
! Compound – substance composed of two or more different elements
! Mixtures – two or more substances are mixed together
o!Types –
! Homogeneous – two or more substances that appear harmony throughout
!Heterogeneous– two or more substances that appear different throughout.
State of matters
!Gas – indefinite shape and volume because particles are far apart from each other and
have weak attractions.
!Liquid – indefinite shape but have definite volume because particles are close together
because they have mild attractions.
! Solid – definite shape and volume because particles are close together and there is strong
attractions
Properties
!Physical – can be measured and observed without changing the composition.
o! Example: color, texture, older, density, melting/boiling points, Features.
!Chemical – how one substance behaves in the presence in another substance
o! Example: combustion, flammability, corrosion.
!Extensive property – depends on the sample size
o! Example: mass, volume.
!Intensive property – independent of sample size
o! Example: density.
How to convert temperature
Fahrenheit (F) = (1.8 x C) + 32
Celsius (C) = (F - 32) ÷ 1.8
Dimensional analysis (converting problems)
!Units are used to help set up the calculation.
1.!82 kg = ? g 1 kg = 1×103 g
82 kg x !"#"$%!&
"!'& = 82, 000 g or 8.2 x 104 g
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2.!16.3 cm = ? nm cm -> m -> nm 1 cm = 1x10 -2 m
1 nm = 1x10-9 m
16.3 cm x "("$)*+
"!,+ x "!-+
"("$).+ = 1.63 x 108 nm
16.3 cm2 = ? mm2 cm2 -> m2 -> mm2
12 cm2 = (1x10 -2 )2 m2 => 1cm2 = 1x10-4 m2
12 mm2 = (1x10 -6 )2 m2 => 1mm2 = 1x10-12 m2
16.3 cm2 x "("$)/+*
"!,+* x "!++*
"("$)0*+* = 1.63 x 109 nm2
3.!Gold has density of 19.3 g/cm³, what is the density in kg/mm3?
1 kg = 1×103 g
13 cm3 = (1x10 -2 )3 m3 => 1cm3 = 1x10-6 m3
13 mm3 = (1x10 -3 )3 m3 => 1mm3 = 1x10-9 m3
19.3 g x "!'&
"("$%& x ",+%!
"("$)1+% x "("$).+%
"!+% = 1.93 x 10-5 kg/mm3
4.!What is the mass of 1.00 ft.³ of gold? In pound?
Density of gold = 19.3 g/cm³
1 lb = 453.6 g
!
19.3 g = 1 cm³
12 in = 1 ft => 123 in3 = 1 ft3 => 1 ft3 = 1728 in3
2.54 cm = 1 in => 2.543 cm3 = 13 in3 => 1 in3 = 16.39 cm3
1.00 ft.³ x "234!5-%
"67% x "89:;!,+%!
"!5-% x ";9:!&
"!,+% x "!<=
>?:98!& = 1.21 x 103 lb
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find more resources at oneclass.com