chem110w2 ms janine kasavel [email protected] 031-2607747 rm: 03-041 1
TRANSCRIPT
2
LECTURES• MONDAY L22 07h45• THURSDAY L22 13h15• FRIDAY L22 08h40
TUTORIAL• WEDNESDAY 10h30 -12h10
3
Quantitative Chemistry •matter•units•significant figures•atomic structure, isotopes, periodic table
•basic nomenclature (ions, molecular &inorganic compounds)•stoichiometry and balancing equations by inspection•moles and Avogadro’s number•empirical and molecular formulae•limiting reagents
4
MATTER“matter is anything that has mass and takes up space”
Pure Substance- ELEMENT: can’t be decomposed into simpler
substances- COMPOUND: composed of 2/> different elements
Mixture-HETEROGENEOUS: visibly different composition, properties
or appearance-HOMOGENEOUS: visibly uniform composition, properties &
appearance throughout
5
Physical properties of matter-measured without changing the identity or composition of the substance
Chemical properties of matter-describe the way a substance may
change or react to form other substances
6
UNITSSystème International (SI)
MASS kilogram kgLENGTH metre mTIME second sTEMPERATURE Kelvin K
G giga 109
M mega 106
k kilo 103
d deci 10-1
c centi 10-2
m milli 10-3
µ micro 10-6
n nano 10-9
p pico 10-12
SCIENTIFIC NOTATION
7
SIGNIFICANT FIGURES1) any figure that is not zero is significant.2) zeroes between non-zero figures are significant.3) exact (“counting”) numbers by definition have an ¥
number of s.f., so physical constants defined to be exact numbers do so also.
4) leading zeroes (to the left of the first non-zero figure) are not significant.
5) trailing zeroes (to the right of the last non-zero figure) are significant only if the number has a d.p.
6) in measurements without a d.p., the number of s.f. is ambiguous.
8
Using Significant Figures in Calculations• multiplication/divisionNumber of s.f. in final answer is the same as the LEAST ofnumbers of s.f. in each of original measurements.
• addition/subtractionNumber of d.p. in final answer is the same as the LEAST ofnumbers of d.p. in each of original measurements.
9
DENSITY
ρ = mass/ volume
ρ: gcm-3
mass: g volume: cm3
10
PRACTICE EXAMPLE
A nugget of gold with a mass of 521 g is added to 50.0 mL of water. The water level rises to a volume of 77.0 mL. What is the density of the gold?
11
ATOMIC STRUCTURE
PROTONS, NEUTRONS in the nucleus surrounded by orbiting ELECTRONS
• Early Atomic Theory (Dalton 1803 – 1807)• Cathode Rays & Particles (Thomson, 1897)• Electron Charge & Mass (Millikan, 1909)• Nuclear Atom (Rutherford, 1910)• Modern Atomic Structure (Rutherford, 1919)
12
Charge Mass
Actual/ Coulombs Relative Actual/
gRelative/
uProton 1.602 x 10-19 + 1 1.673 x 10-24 1.00727
Electron 1.602 x 10-19 - 1 9.109 x 10-28 0.00054858Neutron 0 0 1.675 x 10-24 1.00866
13
I a PERIODIC TABLE OF THE ELEMENTS
VIII a
1
H 1.008
II a
III a
IV a
V a
VI a
VII a
2
He 4.003
3
Li 6.941
4
Be 9.012
5
B 10.81
6
C 12.01
7
N 14.01
8
O 16.00
9
F 19.00
10
Ne 20.18
11
Na 22.99
12
Mg 24.31
III b
IV b
V b
VI b
VII b
┌───VIII b───┐
I b
II b
13
Al 26.98
14
Si 28.07
15
P 30.97
16
S 32.07
17
Cl 35.45
18
Ar 39.95
19
K 39.10
20
Ca 40.08
21
Sc 44.96
22
Ti 47.88
23
V 50.94
24
Cr 52.00
25
Mn 54.94
26
Fe 55.85
27
Co 58.93
28
Ni 58.69
29
Cu 63.55
30
Zn 65.39
31
Ga 69.72
32
Ge 72.61
33
As 74.92
34
Se 78.96
35
Br 79.90
36
Kr 83.80
37
Rb 85.47
38
Sr 87.62
39
Y 88.91
40
Zr 91.22
41
Nb 92.91
42
Mo 95.94
43
Tc *98.91
44
Ru 101.1
45
Rh 102.9
46
Pd 106.4
47
Ag 107.9
48
Cd 112.4
49
In 114.8
50
Sn 118.7
51
Sb 121.8
52
Te 127.6
53
I 126.9
54
Xe 131.3
55
Cs 132.9
56
Ba 137.3
57
*La 138.9
72
Hf 178.5
73
Ta 181.0
74
W 183.8
75
Re 186.2
76
Os 190.2
77
Ir 192.2
78
Pt 195.1
79
Au 197.0
80
Hg 200.6
81
Tl 204.4
82
Pb 207.2
83
Bi 209.0
84
Po *209.0
85
At *210.0
86
Rn *222.0
87
Fr *223.0
88
Ra *226.0
89
**Ac *227.0
*Lanthanides 58
Ce 140.1
59
Pr 140.9
60
Nd 144.2
61
Pm *146.9
62
Sm 150.4
63
Eu 152.0
64
Gd 157.3
65
Tb 158.9
66
Dy 162.5
67
Ho 164.9
68
Er 167.3
69
Tm 168.9
70
Yb 173.0
71
Lu 175.0
**Actinides
90
Th *232.0
91
Pa *231.0
92
U *238.0
93
Np *237.1
94
Pu *244.1
95
Am *243.1
96
Cm *247.1
97
Bk *247.1
98
Cf *251.1
99
Es *252.1
100
Fm *257.1
101
Md *258.1
102
No *259.1
103
Lr *260.1
A: mass number = no. protons + no. neutronsZ: atomic number = no. protons /electrons
AZ E
14
IsotopesAtoms of the same element with different mass numbers due to:
different numbers of neutrons
15
Average atomic mass
AAM: average atomic massIM: isotopic mass
16
PRACTICE EXAMPLE
Naturally occurring Mg has three isotopes: 24Mg (78.90 %) 23.9850 u25Mg (10.00 % )24.9858 u26Mg (11.10 %) 25.9826 u
AAM=?
17
18
IONS• If electrons are added to or removed from a neutral
atom, an ion is formed.
• When an atom or molecule loses electrons it becomes positively charged CATION (E+)
11 p+
11 e-
11 p+
10 e-
Na atom Na+ ion
L.Pillay 2010
19
When an atom or molecule gains electrons it becomes negatively charged ANION (E-).
• Generally, metal atoms tend to lose electrons (forms cations) and non-metal atoms gain electrons (forms anions).
17 p+
18 e-
17 p+
17 e-
Cl atom Cl- ion
L.Pillay 2010
20
CHARGE FORMULA NAME +1 H+ Hydrogen ion
Li+ Lithium ion Na+ Sodium ion K+ Potassium ion
Rb+ Rubidium ion Cs+ Cesium ion Ag+ Silver ion
NH4+ Ammonium ion
Cu+ Copper(I) or cuprous ion +2 Mg2+ Magnesium ion
Ca2+ Calcium ion Sr2+ Strontium ion Ba2+ Barium ion Zn2+ Zinc ion Cd2+ Cadmium ion Co2+ Cobalt(II) or cobaltous ion Cu2+ Copper(II) or cupric ion Fe2+ Iron(II) or ferrous ion Mn2+ Manganese(II) or manganous ion Hg2+ Mercury(II) or mercuric ion Hg2
2+ Mecury(I) or mercurous ion Ni2+ Nickel(II) or nickelous ion Pb2+ Lead(II) or plumbous ion Sn2+ Tin(II) or stannous ion
+3 Al3+ Aluminium ion Cr3+ Chromium(III) or chromic ion Fe3+ Iron(III) or ferric ion
COM
MO
NCA
TIO
NS
21
COM
MO
NAN
ION
S
CHARGE FORMULA NAME - 1 H - H ydride ion
F - F luoride ion Cl - C hloride ion Br - B romide ion I - I odide ion
CN - C yanide ion OH - H ydroxide ion
CH 3 COO - A cetate ion ClO 3
- C hlorate ion ClO 4 - P erchlor ate ion NO 3 - N itrate ion
MnO 4 - P ermanganate ion - 2 O 2 - Oxide ion
O 2 2- P eroxide ion S 2 - S ulfide ion
CO 3 2 - C arbonate ion
CrO 4 2 - C h romate ion C r 2 O 7 2 - D ichromate ion SO 4 2+ S ulphate ion
- 3 N 3 - Nitride ion PO 4
3 - P hosphate ion
22
Ionic compounds• Composed of nonmetal and metal• Cations and anions attract each other to form a neutral compound
NAMES:• Name of metal (cation) written first• If metal has more than one common charge , write the charge in
roman numerals in brackets• Name of nonmetal (anion) written next with –ide ending
FORMULAE:• compounds are electrically neutral, the formula of a compound can
easily be constructed simply by:-writing value of cation charge as subscript on anion-writing value of anion charge as subscript on cation
23
PRACTICE EXAMPLE
NaCl
K2SO4
Ba(OH)2
cobalt(II) nitrate
silver sulfide
ferric chloride
24
OxyanionClO4
- perchlorate ion (one more O atom than chlorate)
ClO3- chlorate ion (one more O atom than chlorite)
ClO2- chlorite ion (one more O atom than hypochlorite)
ClO- hypochlorite ion
Acids- acids containing anions whose names end in -ide are named by
changing the -ide ending to -ic, adding the prefix hydro- to this anion name, and then following with the word acid
- acids containing anions whose names end in -ate/-ite are named by changing the -ate ending to -ic or the -ite ending to -ous and then adding the word acid
25
PRACTICE EXAMPLE
Anion Corresponding acid
Cl-
S2-
ClO4-
ClO3-
ClO2-
ClO-
26
MOLECULAR COMPOUNDS• Generally composed only of nonmetals• Diatomic species includes O2 N2, F2, Br2, I2
NAMING:• name of element furthest left on periodic table generally written first• both elements in same group on periodic table, element with higher Z
written first• name of 2nd element given the ending –ide• Greek prefixes used to indicate number of atoms of each element
Greek prefixes:mono, di, tri, tetra, penta, hexa, hepta, octa, nona, deca
1 2 3 4 5 6 7 8 9 10
27
PRACTICE EXAMPLE
SO2
PCl5
N2O3
NF3
P4S10
silicon tetrabromide
28
STOICHIOMETRY“quantities of substances consumed and produced in chemical reactions”
• Atoms are neither created or destroyed in a chemical reaction.
• A chemical equation must have equal numbers of atoms of each element on each side of the arrow.
• The molecular composition of certain ions must remain the same on each side of the arrow.
29
PRACTICE EXAMPLE
C2H6 + O2 → CO2 + H2O
Al + HCl → AlCl3 + H2
30
MOLE & AVOGADRO’S NUMBER
Number of atoms/molecules/ions represented as mole amounts
Avogadro’s number: NA = 6.022 X 1023
1 mol 12C atoms = 6.022 X 1023 12C atoms
1 mol H2O molecules = 6.022 X 1023 H2O molecules
1 mol NO3
- ions = 6.022 X 1023 NO3- ions
31
Molar mass“Mass in grams of one mole of a substance”• Related to mole amount of a substance by the equation:
n: number of moles (in mol)m: mass (in grams)MM: molar mass (in grams per mole)
m
n MM
32
PRACTICE EXAMPLE
How many oxygen atoms are in 1.50 mol of sodium carbonate?
33
EMPIRICAL AND MOLECULAR FORMULA
“Ratio of atoms of each element in a compound”Mass %
elements
Grams of
each eleme
nt
Moles of
each eleme
nt
Empirical formula
Assume Use molar Calculate 100g mass mole ratio
sample
34
PRACTICE EXAMPLE
Determine the empirical formula of a compound with 10.4% C, 27.8% S and 61.8% Cl.
35
I a PERIODIC TABLE OF THE ELEMENTS
VIII a
1
H 1.008
II a
III a
IV a
V a
VI a
VII a
2
He 4.003
3
Li 6.941
4
Be 9.012
5
B 10.81
6
C 12.01
7
N 14.01
8
O 16.00
9
F 19.00
10
Ne 20.18
11
Na 22.99
12
Mg 24.31
III b
IV b
V b
VI b
VII b
┌───VIII b───┐
I b
II b
13
Al 26.98
14
Si 28.07
15
P 30.97
16
S 32.07
17
Cl 35.45
18
Ar 39.95
19
K 39.10
20
Ca 40.08
21
Sc 44.96
22
Ti 47.88
23
V 50.94
24
Cr 52.00
25
Mn 54.94
26
Fe 55.85
27
Co 58.93
28
Ni 58.69
29
Cu 63.55
30
Zn 65.39
31
Ga 69.72
32
Ge 72.61
33
As 74.92
34
Se 78.96
35
Br 79.90
36
Kr 83.80
37
Rb 85.47
38
Sr 87.62
39
Y 88.91
40
Zr 91.22
41
Nb 92.91
42
Mo 95.94
43
Tc *98.91
44
Ru 101.1
45
Rh 102.9
46
Pd 106.4
47
Ag 107.9
48
Cd 112.4
49
In 114.8
50
Sn 118.7
51
Sb 121.8
52
Te 127.6
53
I 126.9
54
Xe 131.3
55
Cs 132.9
56
Ba 137.3
57
*La 138.9
72
Hf 178.5
73
Ta 181.0
74
W 183.8
75
Re 186.2
76
Os 190.2
77
Ir 192.2
78
Pt 195.1
79
Au 197.0
80
Hg 200.6
81
Tl 204.4
82
Pb 207.2
83
Bi 209.0
84
Po *209.0
85
At *210.0
86
Rn *222.0
87
Fr *223.0
88
Ra *226.0
89
**Ac *227.0
*Lanthanides 58
Ce 140.1
59
Pr 140.9
60
Nd 144.2
61
Pm *146.9
62
Sm 150.4
63
Eu 152.0
64
Gd 157.3
65
Tb 158.9
66
Dy 162.5
67
Ho 164.9
68
Er 167.3
69
Tm 168.9
70
Yb 173.0
71
Lu 175.0
**Actinides
90
Th *232.0
91
Pa *231.0
92
U *238.0
93
Np *237.1
94
Pu *244.1
95
Am *243.1
96
Cm *247.1
97
Bk *247.1
98
Cf *251.1
99
Es *252.1
100
Fm *257.1
101
Md *258.1
102
No *259.1
103
Lr *260.1