Cubic Unit Cell
how many atoms are in a face centered cubic cell?
4 atoms
A solution of Ba(OH)2 (171 g/mole) dissolved in water has a density of 1.26 g/mL.What is the molality (m) of a 5.50M Ba(OH)2 solution?
17.2 m
Consider the reaction
2NO2 (g) = 2 NO (g) + O2 (g)
The initial concentrations are PNO2 = 4.8 atm PO2 = 0 atm PO2 0 atm and the equilibrium pressure of O2 is .32 atm. What is the numerical value of Kp?
7.6x 10-3
What will happen to the equilibrium when the volume of the system is increased?
2SO2 (g) + O2n (g) = 2SO3 (g)
Shifts to the left more moles of gas on the left
Define a unit cell
it is the smallest portion of a crystal lattice
Consider a solution made by dissolving 418 grams of K2SO4(174 g/mole) in 515 grams of H2O (18 g/mole). What is the mole fraction (X) of K2SO4 in this solution?
.077
consider a buffer that is .44 M in HX and .33 M in NaX. HX has a Ka of 2.8x10-6 what is the pH of this buffer solution
pH = 2.8
What is the oxidation number of P in K3PO4?
+5
O= -2
K = +1
Silver crystalizes in a face centered cubic unit cell and the edge length is 4.07 x 10-8 and the density of metallic silver is 10.5 g/cm-3
106.6 g/mol
Typical sea water contains 2.7 g of salt (NaCl) per 100 mL. What is the molarity of NaCl in the ocean? Molecular weight of NaCl is 58.44 g/mol.
.46 M
Consider the weak acid HA that has a Ka of 6.25 x 10-5 calculate the pH of a .175M solution of HA
pH = 2.48
What is the sign of ΔS for: O2(g) = O2(aq) ?
Negative
The edge length of the unit cell of Ta, is 3.306 x 10-8 cm; the unit cell is body-centered cubic. Tantalum has a density of 16.69 g/cm3. Calculate the mass of a tantalum atom.
181.6 g/mol
Find the molarity and molality of 37.0 wt% HCl. The density of a substance is the mass per unit volume. The density of HCl is 1.19 g/mL.
16.1 m
consider a buffer that is .33 M in HX and .28 M in NaX. HX has a Ka of 1.7x10-6 what is the pH of this buffer solution
5.73
For C2H4 (g) + H2 (g) → C2H6 (g); the reaction is exothermic. The reaction will be spontaneous at what approximate temp (high, low, none, all the time etc.)
Low temperatures only.
E=H-TS
H must be negative so - - so low t
Iron (55.85 g/mol) crystallizes in a body-centered cubic unit. The edge length of this cell is 2.87 x 10-8 cm. What is the density of iron?
7.89 g/cm3
Calculate the mole fraction of KI in a solution made by dissolving 83 g of KI (166 g/mol) in 171 g of water (18 g/mol).
.05
Consider the weak acid HA that has a Ka of 2.3 x 10-5 calculate the pH of a .25M solution of HA
pH = 2.6
It takes 12.5 minutes for 0.86 g of Cr metal to be deposited via electrolysis of aqueous Cr2(SO4)3. What current is used? The half-reaction is as follows:
Cr3+(aq) + 3e- à Cr(s)
6.39 A