Chapter 7
As the frequency of light increases, the energy of the photon _______ and the wavelength of light ________.
increases, decreases.
Draw the correct Lewis structure for PCl5. Determine the hybridization around the central
atom and determine its molecular geometry.
sp3
trigonal bipyramidal
use the localized electron model to describe the bonding H2CO.
Trigonal planar geometry. Carbon is the central atom bonded to 2 hydrogens and double bonded to an oxygen. Carbon is Sp2 hybridized
When 100 J of heat flows into a system and the system does 50 J of work, what is the change in internal energy ΔE of the system?
ΔE=q+w=+100 J+(−50 J)=+50 J
system gains energy
If a photon has a frequency of 6.0×1014 Hz, calculate its energy in joules. (Use h=6.626×10-34 J\s).
3.976 x 10-19 J
Estimate the enthalpy change for the reaction:
H2(g)+Cl2(g)→2HCl(g)
-179kJ
write the lewis structure, predict molecular structure (bond angles) and give expected hybrid orbitals and overall polarity for KrF4
Square planar 90º d2sp3 nonpolar
Assign oxidation numbers for each atom in (NH4)2Ce(SO4)3
N: -3 H: +1 Ce: +4 S: +6 O: -2
If an electron has a mass of 9.11×10−31 kg and is moving at 2.2×106 m/s, calculate its de Broglie wavelength.
3.29 x 10-10 m
Estimate the enthalpy change for the reaction:
N2(g)+3H2(g)→2NH3(g)
-97kJ
draw lewis structure and predict molecular structure with hybridization for XeO3
trigonal pyramid sp3
Balance the following in acidic conditions :
Cr2O72- + Fe2+ --> Cr3+ + Fe3+
14H+ + Cr2O72-+ 6Fe2+ --> 2Cr3+ + 7H2O +6Fe3+
The table given to the right below contains the binding energies (for one electron) for various unknown
metals. A photon stream with energy = 385.89 kJ/mol is shot at individual samples of these metals. Which
metals do you expect to produce free electrons? Remember, 1 eV = 1.602 × 10-19 J
all of the metals will release electrons
40.0 ev/photon
Estimate the enthalpy change for the reaction:
C2H4(g)+H2(g)→C2H6(g)
-124kJ
draw lewis structure and predict molecular structure with hybridization for XeOF2
t-shaped dsp3
A 1.20 g sample of a compound is combusted in a bomb calorimeter. The temperature of the 800.0 g of water in the calorimeter rises from 22.50°C to 25.00°C.
Calculate the heat released in kJ/mol if the molar mass of the compound is 60.0 g/mol.
418 kJ/mol
Calculate the wavelength of light emitted when an electron falls from n=3 to n=2 in hydrogen.
656 nm
Draw the correct Lewis structure for the molecule CH3CONH2 and determine the molecular
geometry around each central atom, hybridization and polarity. Is this molecule soluble in
water? Justify your answer.
C1 tetrahedral sp3 nonpolar,
C2 trigonal planar sp2 polar,
N trigonal pyramidal sp3 polar.
there is a net polarity so the whole molecule is polar and therefore, soluble in water.
Draw the molecular orbital diagram for N2-1 and determine the bond order, its
stability and whether it is paramagnetic or diamagnetic. Compare its stability compared to N 2 .
Compare its bond strength and bond length
2.5, stable, paramagnetic
3, stable, diamagnetic
N2 bond strength is stronger than N2-1
What volume of O₂ gas (in liters) at 25°C and 0.980 atm is required to completely react with 4.50 g of C₂H₆ (ethane)?
13.1 L
Hydrogen gas is generated by reacting zinc metal with hydrochloric acid according to the reaction:
Zn (s)+2HCl (aq)→ZnCl2 (aq)+H2 (g)
The hydrogen gas is collected over water at 25.0 °C in an inverted graduated cylinder. The total pressure inside the cylinder is 765.2 mmHg, and the volume of gas collected is 245.0 mL.
The vapor pressure of water at 25.0 °C is 23.8 mmHg.
a) What is the pressure of the dry hydrogen gas in the cylinder?
b) How many moles of hydrogen gas were collected?
a. 0.9755 atm
b.9.72 x 10-3