ThermoChemistry
Given
mass of compound in grams
Standard Heat of Formation (1mole)
Mass * (1mole of compound/molar mass) * (standard heat of formation/1 mole)
Formula to determine heat lost or gained from a system
q=mc∆t
Molarity Formula
Molarity (M) = moles of solute/liters of solution = mol/L
Ideal Gas Law formula
Pv=nRT
Dalton's Law of Partial Pressures
the sum of the partial pressure in a mixture of gases will equal the total pressure
Given: 120.3 g ammonium sulfate ((NH4)2SO4)
ΔH°f = -1180 kJ/mol
Wanted: heat of formation (ΔH°f) in kilojoules?
Hint: 132.14 g/mol (NH4)2SO4
-1075 kJ
Given: ΔH°f = -265.0 kJ Standard
Wanted: grams of cobalt (II) chloride (CoCl2) if ΔH°f = -313 kJ/mol?
Hint: 129.84 g/mol CoCl2
110.1 g CoCl2
A solution of Hg(C2H3O2)2 is diluted from its original concentration of 99 to a new concentration of 30 . If its new volume is 97.8mL , what was the original volume of the concentrated solution?
29.6mL
If 20.5 mol of an ideal gas occupies 80.5 L at 327 K, what is the pressure of the gas?
6.83 atm
If a gaseous mixture of water vapor and oxygen gas has a total pressure of 12.3 atm, and contains water vapor with a pressure of 6.2 atm.
Then what is the pressure of O2 gas?
6.1 atm
Calculate the standard enthalpy (ΔH) for this reaction: 2 NH3 (g) → N2 (g) + 3 H2 (g)
using the following standard heats of formation: H2 (g)ΔH°f = 0 kJ/mol N2 (g)ΔH°f = 0 kJ/mol NH3 (g)ΔH°f = -45.561 kJ/mol
+91.122 kJ
H2(g)+F2(g)⟶2HF(g)Δ𝐻∘rxn=−546.6 kJ
2H2(g)+O2(g)⟶2H2O(l)Δ𝐻∘rxn=−571.6 kJ
calculate the value of Δ𝐻∘rxn for
2F2(g)+2H2O(l)⟶4HF(g)+O2(g)
-521.6 kJ
A solution of Li2SO3 at 40M is diluted from its original volume of 30L by adding 54.3M . What is the resulting concentration of this solution?
14.2M
If 3.55 mol of an ideal gas has a pressure of 1854.4 torr and a volume of 61.87 L, what is the temperature of the sample in degrees Celsius?
245 C
A mixture of He, N2, and Ar has a pressure of 16.0= atm at 28.0 °C. If the partial pressure of He is 2151 torr and that of Ar is 2291 mm Hg, what is the partial pressure of N2?
USE atm
10.2 atm
Substance: argon (Ar)
specific heat capacity (c): 0.5203 J/(g·K)
amount (m): 799.5 g
temperature change (ΔT): +951.51 K
heat transferred (q) in joules (J)?
395800 J
A sample of gas occupies a volume of 50.5 mL50.5 mL. As it expands, it does 114.7 J114.7 J of work on its surroundings at a constant pressure of 783 Torr783 Torr. What is the final volume of the gas?
Hint: 760Torr=1atm
1150 mL
0.0606 mol of LiNO3 is dissolved in water to produce a solution with a concentration of 0.790 M. What is the volume of this solution in liters?
0.0767 L
A gaseous compound has a density of 1.75 g/L at 23.4 °C and 1.15 atm. What is the molar mass of the compound?
37.0 g/mol
17.5 L N2 at 25 °C and 125 kPa and 32.3 L O2 at 25 °C and 125 kPa were transferred to a tank with a volume of 7.00 L. What is the total pressure at 45 °C?
(8.3145 L⋅kPa/mol⋅K)
949 kPa
A generic solid, X, has a molar mass of 70.970.9 g/mol. In a constant‑pressure calorimeter, 39.739.7 g of X is dissolved in 367367 g of water at 23.00 °C.
X(s)⟶X(aq)X(s)⟶X(aq)
The temperature of the resulting solution rises to 28.1028.10 °C. Assume the solution has the same specific heat as water, 4.184 J/(g·°C), and that there is negligible heat loss to the surroundings.
How much heat was absorbed by the solution?
What is the enthalpy of the reaction?
8.68kJ
-15.5kJ/mol
If you combine 350.0 mL of water at 25.00 ∘C and 120.0 mL of water at 95.00 ∘C,
what is the final temperature of the mixture?
Use 1.00 g/mL as the density of water.
42.87 degrees Celcius
23.2 g of MgCl2 are dissolved 0.452in 0.54 L of water. What is the concentration of this solution in molarity?
0.452 M
Hydrazine, N2H4, reacts with oxygen to form nitrogen gas and water.
N2H4(aq)+O2(g)⟶N2(g)+2H2O(l)
If 3.15 g= of N2H4 reacts with excess oxygen and produces 0.650 L of N2, at 295 K and 1.00 atm, what is the percent yield of the reaction?
27.3%
Calculate the pressure of 1.00 mol of argon gas at 7.50 L and 273 K using
(a) the ideal gas equation and (b) the van der Waals equation.
Non ideal gas Van der Waals constant: a=1.336 b= 0.0320
9.63 atm