Solution Stoichiometry
What are the oxidation numbers of all the elements in Ca(NO3)2 ?
Ca = +2, N = +5, O = -2
What is the enthalpy change (in kJ) of a chemical reaction that raises the temperature of 250.0 ml of
solution having a density of 1.25 g/ml by 7.80°C? (The specific heat of the solution is 3.74 j/g ∙ K.) (Hint: pay attention to the sign!)
-9.12 kJ
What is the average speed in m/s (root-mean-square speed) of a carbon monoxide molecule at 27°C?
517 m/s
In the drawn phase diagram, which phase is the densest?
Solid
Assuming ideal behavior, which of the following gas samples will have the greatest average speed at
355 K?
A) Ne B) CH4 C) Cl2 D) C2H4 E) They will all have the same average speed
B) CH4
Which of the following reagents could NOT be used to separate Cl- from S2- in an aqueous solution?
A) Ca(NO3)2(aq); B) Cu(NO3)2(aq); C) AgNO3(aq); D) Fe(NO3)3(aq)
C) AgNO3(aq)
Using the given information:
IF7(g) + I2(g) → IF5(g) + 2 IF(g), ΔH°rxn = -89 kJ
ΔH°f of IF7 (g) = -941 kJ/mol, ΔH°f of IF5 (g) = -840 kJ/mol
Calculate ΔH°f for IF (g)
-95 kJ/mol
An unknown gas effuses 1.73 times faster than krypton. What is the molar mass of the gas (in g/mol)?
28.3 g/mol
In the drawn phase diagram, name the labeled processes.
A) Melting
B) Vaporization
C) Sublimation
What is the correct net ionic equation for the reaction between CaCl2 (aq) and Na2SO4 (aq)?
Ca2+ (aq) + SO42- (aq) --> CaSO4 (s)
What is the oxidizing agent in this reaction? Zn (s) + 2HCl (aq) --> ZnCl2 (aq) + H2 (aq)
HCl
Using the following bond energies, calculate ΔH for the reaction of methane with fluorine: CH4 (g) + 2F2 (g) --> CF4 (g) + 2H2 (g)
(C-F = 450 kJ/mol, C-H = 410 kJ/mol, F-F = 158 kJ/mol, H-H = 436 kJ/mol)
-716 kJ
A 57.0 mL canister holds a gas sample with at 322 K and 1.90 atm. To what temperature (in K) must the
gas in the canister be heated/cooled in order to have a volume of 87.0 mL at 2.30 atm?
595 K
Let K be the equilibrium constant for the reaction N2 (g) + 3 H2 (g) ⇌ 2 NH3 (g).
Express the equilibrium constant for the reaction NH3 (g) ⇌ (1/2)N2 (g) + (3/2) H2 (g) in terms of K
1/[K^(1/2)]
In the reaction P4(s) + 10Cl2(g) → 4PCl5(s), what is the reducing agent?
P
Write the net ionic equation for the acid-base reaction between HCN (aq) and NaOH (aq)
HCN (aq) + OH-(aq) --> H2O (l) + CN-
If ΔH° = -2046 kJ for the reaction: C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g)
Find ΔH° in kJ for the reaction C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(l).
(The heat of vaporization of water is 44.0 kJ/mol)
-2222 kJ
The following reaction is used to generate hydrogen gas: Mg(s) + 2 HCl(aq) → MgCl2(aq) + H2(g)
If 243 mL of gas is collected over water at 25°C and has a total pressure of 0.980 atm, what mass of hydrogen is produced (in g)? (At 25°C, water vapor pressure is 0.0310 atm)
0.0190 g
Given the equilibrium constants for the following reactions:
4Cu(s) + O2(g) ⇌ 2Cu2O(s), K1
2CuO(s) ⇌ Cu2O(s) + (1/2)O2(g), K2
what is K for the system in terms of K1 and K2?
2Cu(s) + O2(g) ⇌ 2CuO(s)
[K1^(1/2)]/K2
When 5.03 g of solid KOH are dissolved in 100.0 mL of distilled water in a coffee-cup calorimeter, the temperature of the liquid increases from 23.0°C to 34.7°C. The density of water in this temperature range averages 0.9969 g/cm3. What is ΔHsoln (in kJ/mol)? Assume that the calorimeter absorbs a negligible amount of heat and the specific heat of the solution is the same as pure water
-57.2 kJ/mol
A bottle containing 1.00L of wine (containing ethanol, C2H5OH) with a loose cork was exposed to oxygen and became sour (acetic acid, CH3COOH).
𝐶2𝐻5𝑂𝐻+𝑂2 →𝐶𝐻3𝐶𝑂𝑂𝐻+𝐻2𝑂
When 1.00 mL of this soured wine was analyzed, it showed that there were 0.0563 g of acetic acid in that 1.00 mL sample. Determine how much of wine remain un-soured (in mol). (wine is 8.5% v/v and has density of 0.800 g/mL)
0.538 mol
Calculate the lattice energy for LiBr(s), in kJ/mol, given the following:
sublimation energy for Li(s) +166 kJ/mol
ΔHf for 1mol Br(g) +97 kJ/mol
first ionization energy of Li(g) +520. kJ/mol
electron affinity of Br(g) –325 kJ/mol
enthalpy of formation of LiBr(s) –351 kJ/mol
(Hint: In the standard state, Li exists as a solid and Br exists as Br2 (l) )
-809 kJ/mol
A mixture of three gases (N2, Ar, and O2) at 2.6 atm is found to contain 23% N2, 3.0% Ar by mass, and 74% O2. What is the partial pressure of Ar?
0.0608 atm
The following plots represent vapor pressure vs. temperature curves for diethyl ether, ethanol,
and water, not necessarily in that order. Based on the relative strengths of the intermolecular forces of attraction of each substance, which is the most likely curve for ethanol?
Curve B
Determine the oxidation number change of carbon in reaction 1. What chemical species in reaction 2 is undergoing the same process (oxidation or reduction) carbon underwent?
𝐶𝐻4 (𝑔) + 𝑂2 (𝑔) → 2𝐻2𝑂 (𝑔) + 𝐶𝑂2 (𝑔) [𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛 1]
𝑍𝑛 (𝑠) + 2𝐴𝑔𝑁𝑂3 (𝑎𝑞) → 𝑍𝑛(𝑁𝑂3)2 (𝑎𝑞) + 2𝐴𝑔 (𝑠) [𝑟𝑒𝑎𝑐𝑡𝑖𝑜𝑛 2]
Zn