Thermochemistry
During heating, the molecules are speeding up while during a phase change they are changing position
If I have 150 mL of a 5M NaCl solution, how many grams of NaCl do I have in the solution?
43.83 g NaCl
For the reaction 2A + 3B → 4C + 5D, the rate of the reaction in terms of ΔA would be written as?
– ½ ∆A/∆t
Write the equilibrium constant expression for Keq
2H2S (g) + 3O2 (g) <--> 2H2O (g) + 2SO2 (g)
[H2O]2[SO2]2/[H2S]2[O2]3
An ionic salt and water
Find the change in temperature if the mass of a metal is 561 grams, released 6501 J and the specific heat of the metal is 0.651 J/g˚C
∆T = -17.8˚C
What compound is most soluble at 20˚C?
NaNO3
Collision theory assumes that the rate of a reaction depends on what two things?
Energy of collisions and orientation of collisions
_NH3 (g) + _O2 (g) ↔ _NO (g) + _H2O (g) + energy
Determine the direction of shift resulting from each applied stress. Explain your reasoning:
a. Addition of NO (g)
b. Removal of O2 (g)
c. Increase the pressure by decreasing the volume
d. Decreasing the temperature
e. Adding a catalyst
a. Shift Left
b. Shift Left
c. Shift Left
d. Shift Right
e. No change
What is the combined gas law?
P1V1/T1 = P2V2/T2
The specific heat of iron is 0.444 J/g˚C. Calculate the molar heat capacity in kJ/mol˚C
0.0248 J/mol˚C
If I add 1 L of H2O to a 1 L of 1M solution HCl, what is the molarity of the diluted solution?
0.5 M
For the reaction A + B → Products, the following initial rates were found. What is the rate law?
Trial [A] [B] Initial Rate
Trial 1: 0.50 M 1.50 M 4.2 x 10-3
Trial 2: 1.50 M 1.50 M 1.3 x 10-2
Trial 3: 3.00 M 3.00 M 5.2 x 10-2
Rate = k[A][B]
For the reaction, A ↔ 2B, Kc = 2. Suppose 3.5 moles of B and 2.0 moles of A are introduced into a 2.00 L flask. Calculate Q, determine if this reaction is at equilibrium, and if not, what direction it will shift.
Q = 3.06
Not at equilibrium - the reaction will shift left
A sample of argon gas at STP occupies 56.2 liters. Determine the number of moles of argon and the mass in the sample.
2.51 moles Ar
100.27 g Ar
A piece of metal weighing 42.3 g was heated to 88˚C and then put into 150 mL (initially at 25.5˚C). The metal and water were allowed to come to an equilibrium temperature, determine to be 29.2˚C. Calculate the specific heat of the metal.
0.933 J/g˚C
What is the difference between a saturated, unsaturated, and supersaturated solution?
Saturated --> Maximum amount of solute dissolved
Unsaturated --> More solute can be dissolved
Supersaturated --> More than the maximum amount of solute is in the solution
A scientist conducts an experiment to determine the rate of NO formation in the reaction: N2(g) + O2(g) → 2NO(g) If the initial concentration of N2 was 0.500 M and the concentration of N2 was 0.450 M after 0.100 s, what is the rate of NO formation?
1.00 M/s
Phosphorus pentachloride decomposes into Phosphorous trichloride and Chlorine gas. 0.500 moles of pure Phosphorus pentachloride is placed in a 2.00 L bottle. What are the resulting concentrations?
PCl5 (g) ⇔ PCl3 (g) + Cl2 (g) Kc = 2.11 x 10-4
[PCl5] = .25 M, [PCl3] and [Cl2] = 0.00726
You have 0.0245 M HCl solution. What is the [H+], [OH-], pOH, and pH of the solution?
[H+] = 0.0245M
pH = 1.61
pOH = 12.39
[OH-] = 4.07 x 10-13
How many joules of heat are required to heat a 50 g block of ice from -45˚C to 75˚C?
37077.5 J
How many grams of SrCl2 would be required to produce a 3.5 M solution with a volume of 2 L?
1109.64 g
A + 2B + 3C → 2Y + Z
Trial Initial [A] Initial [B] Initial [C] Rate
#1 0.10 0.02 0.04 10 M/hr
#2 0.10 0.03 0.04 15 M/hr
#3 0.20 0.02 0.08 80 M/hr
#4 0.20 0.02 0.16 160 M/hr
#5 0.05 0.01 0.08 ?
a. What is the rate law for the reaction above?
b. What is the rate for trial #5 above?
Rate = k[A]2[B][C]
Trial 5 Rate = 2.5 M/hr
H2 + I2 ↔ 2HI Keq = 1.6 x 10-5
The system starts with 0.10 M of H2 and I2. What are the concentrations of all compounds at equilibrium?
[H2] and [I2] = 0.10 M
[HI] = 4 x 10-4 M
5.600 g of solid CO2 is put in an empty sealed 4.00 L container at a temperature of 300 K. When all the solid CO2 becomes gas, what will be the pressure in the container?
0.782 atm