Module 1
First Question on wordpress.
What is the question for density?
D = m / V
Write a balanced chemical equation for Aluminum metal combining with Oxygen in the air to form aluminum oxide
_ Al + _O2 -> Al2O3
4Al + 3O2 -> Al2O3
Determine the shortest frequency of light required to remove an electron from a sample of Ti metal if the
binding energy of titanium is 3.14 × 10^3 kJ/mo
7.87 × 10^15 H
What is the molecular geometry of ClF4-?
Square planar
How much heat is absorbed by a copper penny with mass 3.10 g whose temperature rises from −8.0 °C to 37.0 °C?
53.7 𝐽
Calculate the atomic mass of silver if silver has 2 naturally occurring isotopes with the following masses and natural abundances:
Ag-107 106.90509 amu 51.84%
Ag-109 108.90476 amu 48.16%
Atomic mass = 107.87 amu
How many mL of 0.218 M sodium sulfate react with exactly 25.34 mL of 0.113 M BaCl2 given the reaction:
BaCl2 (aq) + Na2SO4 (aq) → BaSO4 (s) + 2NaCl (aq)
13.1 mL
Calculate the energy change associated with the transition from n = 4 to n = 1 in the hydrogen atom.
A) +4.89 × 10-18 J
B) +1.64 × 10-18 J
C) -6.12 × 10-18 J
D) +3.55 × 10-18 J
E) -2.04 × 10-18 J
-2.04 × 10-18 J
Place the following in order of increasing dipole moment.
I. BCl3 II. BIF2 III. BClF2
II < III < I
An LP gas tank in a home barbeque contains 13.2 kg of propane, C3H8. Calculate the heat (in kJ) associated with the complete combustion of all propane in the tank. (LP= liquefied petroleum).
C3H8(𝑔) + 5O2(g) → 3CO2 𝑔 + 4H2O(𝑔)
∆𝐻𝑟𝑥𝑛 = −2044 kJ
−6.12x10^(5) kJ
Determine the charge of each elements.
a) Magnesium with 10 electrons
b) Sulfur with 18 electrons
c) Iron with 23 electrons
+2
-2
+3
Many computer chips are manufactured from silicon, which occurs in nature as SiO2. When SiO2 is heated to melting, it reacts with solid carbon to form liquid silicon and carbon monoxide gas. In an industrial preparation of silicon, 155.9 Kg of SiO2 reacts with 78.3 kg of carbon to produce 66.6 kg of silicon. Determined the limiting reactant, theoretical
yield (in grams) and percent yield for the reaction.
LR: SiO2; T.Y.: 72.87 x 103 g , %Yield: 91.4 %
Write electron configurations and short electron configuration for each element:
a) Cl
b) Si
c) Sr
d) O
Google.
The orbital hybridization on the carbon atoms in OCN- is _______
A) sp3
B) sp3d2.
C) sp2d.
D) sp
E) sp2
D
Calculate the pressure exerted by 84.0 g of ammonia, NH3, in a 5.00 L container at 200. oC using Van der Waals equation. 𝑎 = 4.17 𝐿2 𝑎𝑡𝑚/ 𝑚𝑜𝑙^(2)
𝑏 = 0.0371 𝐿 / 𝑚𝑜𝑙
P = 35.7 atm
Perform each unit conversion. Consider significant figures. (Tip: 1 L =1000 mL; 1 mL = 1 cm3; 1 yd = 36 in; 1 in = 2.54 cm, 1 ft = 30.48 cm)
a. 25.6 yd2 to cm2
b. 18. ft3 to L
2.14 𝑥10^5 𝑐𝑚^2
5.1 𝑥10^2 𝐿
A sample of gas has a mass of 0.136 g. Its volume is 0.112 L at a temperature of 298 K and a pressure of 1.06 atm. Calculate the molar of the gas.
28.0 𝑔/𝑚𝑜𝑙
Place the following in order of increasing metallic character.
Rb Cs K Na
A) K < Cs < Na < Rb
B) Na < K < Rb < Cs
C) Cs < Rb < K < Na
D) K < Cs < Rb < Na
E) Na < Rb < Cs < K
B
A molecule containing a central atom with sp3d hybridization has a(n) ________ electron geometry.
A) trigonal bipyramidal
B) octahedral
C) bent
D) square pyramidal
E) trigonal pyramida
A
A 0.225 mol sample of He has a volume of 4.65 L. How many moles must be added to give 6.48 L?
moles added = 0.313548 mol - 0.225 mol = 0.0885 mol
A sample of 15.50 g of dinitrogen monoxide, N2O, decomposes into 9.866 g of nitrogen and 5.634 g of oxygen. A sample of 25.50g N2O decompose into 16.23 g of nitrogen and 9.269 g of oxygen. Show that the amount of nitrogen and oxygen obtained in each
decomposition is consistent with the law of definite proportions.
Mass ratio 1 =1.751
Mass ratio 2 = 1.751
A city of 100,000 people uses approximately 1.0 x 1011 kJ of energy per day. Suppose all of that energy comes from the combustion of liquid octane (C8H18) to form gaseous water and gaseous carbon
dioxide. Use standard enthalpies of formation to calculate ∆𝐻𝑟𝑥𝑛^(𝑜) for the combustion of octane and then determine the number of kilogram of octane necessary to provide this amounts of energy.
C8H18 𝑙 + O2(g) -> + H2O 𝑔 + CO2(𝑔)
𝐻𝑓 => C8H18 = -250.1, O2 = 0, H2O = -241.8, CO2 = -393.5 kJ
2.3 x 10^(6) kg C8H18
Identify the number of bonding pairs and lone pairs of electrons in carbon dioxide.
A) 2 bonding pairs and 4 lone pair
B) 2 bonding pairs and 2 lone pairs
C) 4 bonding pairs and 4 lone pairs
D) 4 bonding pairs and 1 lone pair
E) 4 bonding pairs and 2 lone pairs
C
Place the following in order of increasing IE1.
N F As
A) N < As < F
B) As < N < F
C) F < N < As
D) As < F < N
E) F < As < N
B
A 32.5 g cube of aluminum initially at 45.8 °C is submerged into 105.3 g of water at 15.4 °C. What is the final temperature of both substances at thermal equilibrium?
𝐶𝑠,𝐴𝑙 = 0.903 ΤJ g oC
𝐶𝑠,𝐻2𝑂 = 4.18 ΤJ g oC
𝑇𝑓𝑖𝑛𝑎𝑙 = 17.3 𝑜𝐶