Titrations
What is the equivalence point?
when the amount of acid equals the amount of base during any acid-base titration
Place the following in increasing order of molar entropy at 298K. NO, CO, SO
CO < NO < SO
The rate constant for the first order decomposition of N2O is 3.40 s-1 What is the half life of the decomposition?
0.204 s
Identify the compound with the lowest boiling point.
CH3CH2CH3
CH3OCH3
CH3CHO
CH3CN
CHCl3
CH3CH2CH3
The following reaction is exothermic. What change would make the equilibrium shift to the left?
2 SO2 (g) + O2 (g) >< 2 SO3 (g)
raising the temperature, adding SO3, removing O2, removing SO2
A 25.0 mL sample of 0.100M propanoic acid (HC3H5O2) Ka= 1.3x10-5 with 0.100 M KOH.
Find the initial pH of the solution.
2.94
The molar solubility of Ag2S is 1.26x10-16 M in pure water. Calculate the Ksp for Ag2S.
8.00 x 10-48 M
Determine the Δ Hsolute for KBr if the Δ Hsolution (CaCl2)= -120 kJ/mol and the Δ Hhydration (CaCl2)=-2378 kJ/mol.
2258 kJ/mol
Place the following compounds in order of decreasing strength of intermolecular forces.
I. CH3CH2CH2CH2CH2CH3
II. (CH3)3CCH3
III. (CH3)3CCH2CH3
IV. (CH3)2CHCH(CH3)2
I>IV>III>II
What is the pH of pure water at 40.0 degrees C if the Kw at this temperature is 2.92x10-14
6.767
A 25.0 mL sample of 0.100M propanoic acid (HC3H5O2) Ka= 1.3x10-5 with 0.100 M KOH.
Find the pH after the addition of 4.0 mL of KOH.
4.17
Above what temperature does the following reaction become nonspontaneous?
2H2S (g) + 3O2 (g) >>> 2SO2 (g) + 2H2O (g)
ΔH= -1036 kJ
ΔS= -153.2 J/K
6762 K
An aqueous solution has a normal boiling point of 103.0 degrees C. What is the freezing point of this solution? For water Kb=0.51 C/m and Kf=1.86 C/m.
-11 degrees C
How much energy is required to vaporize 23.9g of ethanol (C2H5OH) at its boiling point, if the Δ Hvap of ethanol is 40.7kJ/mol? The molar mass of ethanol is 46.07 g/mol
21.1 kJ
A reaction mixture at 780 C initially contains 0.500M of CO and 1.00 M of H2. At equilibrium, the CO concentration is found to be 0.15M. Determine the value of the equilibrium constants, Kc and Kp for this reaction.
Kc=25.9
Kp= 3.47x10-3
A 25.0 mL sample of 0.100M propanoic acid (HC3H5O2) Ka= 1.3x10-5 with 0.100 M KOH.
How much KOH must be added to reach the equivalence point? What is the pH of the equivalence point?
0.025 L KOH
pH= 10.9
A solution containing CaCl2 is mixed with a solution of Li2C2O4 to form a solution that is 2.1 × 10-5 M in calcium ion
and 4.75 × 10-5 M in oxalate ion. What will happen once these solutions are mixed? Ksp (CaC2O4) = 2.3 × 10-9.
A) Nothing will happen since Ksp > Q for all possible precipitants.
B) A precipitate will form since Q > Ksp for calcium oxalate.
C) Nothing will happen since calcium oxalate is extremely soluble.
D) Nothing will happen since both calcium chloride and lithium oxalate are soluble compounds.
E) There is not enough information to determine
A
A solution contains 0.25mol Al2(SO4)3 and 0.957mol H2O. Calculate the vapor pressure of the solution at 55 degrees C. Vapor pressure of pure water at 55 degrees C is 187.5 torr.
81.3 torr
Determine the vapor pressure (in mm Hg) of a substance at 29 C, whose normal boiling point is 76 C and has Δ Hvap of 38.7 kJ/mol.
96 mm Hg
Determine the pH of a 0.22 M NaF solution at 25 degrees C. The Ka of HF is 3.5x10-5
8.90
A 25.0 mL sample of 0.100M propanoic acid (HC3H5O2) Ka= 1.3x10-5 with 0.100 M KOH.
Find the pH after the addition of 30.0mL of KOH.
11.96
Calculate ΔS°rxn for the following reaction. The S° for each species is shown below the
reaction.
C2H2(g) + H2(g) → C2H4(g)
S°(J/mol∙K) 200.9 130.7 219.3
-112.3 J/K
The following data were obtained for the reaction of persulfate and iodide.
S2O82- (aq) + 3I- (aq) >>> 2SO42- (g) + I3- (aq)
a) Determine the reaction order with respect to each reactant.
b) Determine the rate law and the value of the rate constant.
rate=(36 M-1s-1)[S2O82-][I-]
To treat a burn on his hand, a person decides to place an ice cube on the burned skin. The mass of the ice cube is 18.0g, and its initial temperature is -13.4 C. The water resulting from the melted ice reaches the temperature of his skin, 30.1 C. How much heat is absorbed by the ice cube and resulting water? Assume all water remains in the hand.
8.77 kJ
Determine the pH of a solution that is 0.15 M HClO2 (Ka= 1.1x10-2) and 0.15 M HClO (Ka= 2.9x10-8).
1.39