IMF's
1. Which bond is temporary/instantaneous?
(LDF, dipole-dipole, ion-dipole, H-bond)
2. Which bond is permanent?
1. LDF is temporary/instantaneous!
2. Dipole-dipole is permanent
Is b) an H-bond
a) Yes! the lone pairs on the N are attracted to the H that is attached to another N; N.......H-N is an H-bond
b) NOOO. H-Cl is NOT F,O,N. this is only dipole dipole
Which molecule has a 120º bond angle?
(draw the lewis structure)
CO2 NH3 IF3 SO3
SO3
How many moles of H2O are in 5g of H2O?
5g H2O x 1 mole H2O/ 18.02g H2O =0.277 moles H2O
How many pi and sigma bonds are in this compound?
pi= 4
sigma= 15
Determine all IMF's present in C2H5OH
(draw the lewis structure!)
LDF, dipole-dipole, and H-bond
blanks: nonpolar or polar
CH4 contains _____ bonds and is _______
CCl4 contains _____ bonds and is _______
CO2 contains ______ bonds and is ______
SO2 contains ______ bonds and is ______
CH4 contains NONPOLAR bonds and is NONPOLAR
CCl4 contains POLAR bonds and is NONPOLAR
CO2 contains POLAR bonds and is NONPOLAR
SO2 contains POLAR bonds and is POLAR
A central atom has 2 lone pairs and 3 single bonds. What is the molecular geometry?
T-shaped
How many molecules of Carbon are in 0.05 kg of C2H6O2? (molar mass C2H6O2= 62.08g/mol)
9.697 x 1023 molecules Carbon
or 9.7 x 1023 molecules Carbon
Easy: Bromine has two naturally occurring isotopes. The most abundant isotope (50.69%) is 7935 Br with mass of 78.9183 amu. What is the other isotope?
a) 7936Br b) 8136 Br c) 8135 Br
Hard: Lithium has 2 naturally occurring isotopes 6Li and 7Li, with masses 6.015 amu and 7.016 amu, respectively. What is their relative abundance of each isotope?
easy: c) 8135Br
hard: 6Li= 7.49% 7Li= 92.51%
Why does H2O have stronger IMF's than H2S ?
(similar question was on your quiz)
H2O can hydrogen bond!
H2S is bigger, so yes it contains stronger LDF forces BUT H2O can H-bond with itself so H-bond is stronger than LDF therefore it has stronger IMF's.
Why is the boiling point of Br2 higher than that of Cl2?
a) Br2 has a greater molar mass
B) Br is less electronegative and therefore its bonding is more ionic
c) Br is more electronegative and has greater dipole-dipole forces
d) Br2 is more polarizable and therefore has greater LDF forces
D: Br2 is more polarizable and therefore has greater LDF forces
According to VSEPR, what are the approximate values of bond angles X & Y
X= 109.5º
Y=120º
A single tablet of Tylenol contains 325 mg of acetaminophen (C8H9NO2). How many moles af acetaminophen are in a single tablet of Tylenol?
molar mass of C8H9NO2: 151.2 g/mol
0.00215 moles or 2.15 x 10-3 moles
which figure illustrates a pi bond?
D
Rank these in INCREASING london dispersion forces
a) C2H6 C4H10 & C6H14
b) F2 Cl2 Br2 I2
a) C2H6 < C4H10 < C6H14
they're getting longer (more mass) = stronger LDF
b) F2 < Cl2 <Br2 < I2
I2 is most polarizable
Determine the IMF's in each and rank them in order of INCREASING BOILING POINT: HCl, HF, and F2
F2 < HCl < HF
F2 = LDF only; temporary force
HCl= dipole-dipole, LDF
HF= H-bond, dipole-dipole, and LDF
a) What is the hybridization on the central atom in GeCl2? (draw the lewis structure)
b) What is the hybridization of the 2 labeled carbon atoms?
is it sp, sp2, sp3, sp3d?
a) sp2
b) C1= sp3 & C2= sp
C8H11N3O3S is used antiretroviral medication. What mass (in g) of Nitrogen is in 7.43 x 10-4 moles of C8H11N3O3S? (molar mass = 198.2 g/mol)
3.12x10-2 g N or 0.0312 g N
you did NOT need molar mass for this problem. Molar mass may be given to you to throw you off.
a) What is the molar mass of carbonic acid?
b) How many moles of hydrogen are in 6 moles of Ca(OH)2?
a) know that carbonate= CO32- and the acid naming makes it H2CO3
H= 2 x 1.01 g/mol=2.02 g/mol
C= 1 x 12.01 g/mol = 12.02 g/mol
O= 3 x 16.0 g/mol = 48 g/mol
H2CO3 : 62.04 g/mol
b) 6 mols Ca(OH)2 x (2 moles H)/ (1mol Ca(OH)2) = 12 moles H
Which of the following is an H-bond?
b is an H-bond
Which purest substance has the lowest boiling point?
a) is correct!
smaller than b) and no H-bond like c)
1. What are the MOLECULAR GEOMETRIES of XeF2 and XeF4? (what's the SN; go from there)
2. What are the polarities of these molecules? (polar or nonpolar)
1. XeF2 : SN =5; 2 bonds, 3 lone pairs) --> linear :)
XeF4 : SN = 6; 4 bonds 2 lone pairs --> square planar :)
XeF2=non polar
XeF4=non polar
A typical silicon chip, such as those in electronic calculators has a mass of 0.23 mg. Assuming the chip is pure silicon, how many silicon atoms are in the chip?
4.9 x 1018 atoms of silicon
What are the smallest whole number coefficients for each substance in the chemical equation when balanced?
__ AgI + __ Na2S--> __Ag2S + __NaI
a) 2, 1, 1, 2
b) 1, 0.5, 0.5, 1
c) 2, 3, 3, 1
d) 4, 2, 2, 4
a) 2,1,1,2
d) is almost correct, but you need to SMALLEST whole number; so divide by 2 to get a)