Ch. 5: Stoichiometry/Titration/Molarity
How many mL of a 2.50 M NaOH solution are required to make 525 mL of a 0.150 M NaOH solution?
31.5 mL
What must the sign of the charge of enthalpy of a reaction for an endothermic
reaction? Which is most likely to be more thermodynamically stable: products or
reactants?
Heat is absorbed (+)
Reactants are low in energy and absorb energy to reach the higher energy of the products.
How much energy is required to heat 80 grams of water from 26oC to 48oC?
7.3 x 103 J
If 3.47mol of an ideal gas has a pressure of 2.85atm and a volume of 65.73L, what is the temperature of the sample? Give answer in Kelvin.
658 K
Calculate the density of Fr(NO3)3 at 149oC and a pressure of 843 mmHg.
7.74 g/L
The titration of 10.00 mL of HCL solution of unknown concentration requires 12.54 mL
of a 0.100 M NaOH solution to reach the equivalence point. What is the concentration
of the unknown HCl solution in M?
0.1254 M
Which is true if H = -95 J?
A) Both the system and the surroundings are gaining 95 J.
B) Both the system and the surroundings are losing 95 J.
C) The system is gaining 95 J while the surrounding is losing 95 J
D) The surroundings is gaining 95 J while the system is losing 95 J
D
In a coffee-cup calorimeter, 100.0 g of H2O and 100.0 mL of HCl are mixed. The HCl had an initial temperature of 44.6oC and the water was originally at 24.6oC. After the reaction, the temperature of both substances is 31.3oC. Was the reaction exothermic or endothermic? Explain.
Exothermic, the temperature decreased from 44.6oC to 31.3oC indicating energy was released by the HCl.
An unknown gas with a mass of 205 g occupies a volume of 20.0 L at standard temperature and pressure. What is the molar mass of the gas?
230. g/mol
An Erlenmeyer flask in a lab has a total pressure of 3.5atm and contains 1.23 mol of O2,
0.32 mol of N2, 2.43 mol of NH3, 0.987 mol of Ar and 10.34 mol of Ne.
a) Find the partial pressure of O2 in the mixture
b) Find the partial pressure of Ar in the mixture
a) 0.28 atm O2
b) 0.064 atm Ar
It takes 38 mL of 0.75 M NaOH solution to completely neutralize 155 mL of a sulfuric
acid solution (H2SO4). What is the concentration of the H2SO4 solution?
0.184 M
A layer of copper welded to the bottom of a skillet weighs 125 g. How much heat is needed to raise the temperature of the copper layer from 25 degrees Celsius to 300 degrees Celsius? (Cs of Cu= .387J/g*C)
1.33 x 104 J
In a coffee-cup calorimeter, 100.0 g of H2O and 100.0 mL of HCl are mixed. The HCl had an initial temperature of 44.6oC and the water was originally at 24.6oC. After the reaction, the temperature of both substances is 31.3oC. Calculate how much heat the water lost or gained in Joules.
2.80 x 103 J
What volume of O2 gas at 25oC and 1.04 atm is needed for the complete combustion of 5.53 grams of propane (C3H8)?
C3H8 + 5O2 → 3CO2 + 4H2O
14.8 L
A container holds 500. mL of CO2 at 20. ° C and 742 torr. What will be the volume of
the CO2 if the pressure is increased to 795 torr?
467 mL
If it takes 25 mL of 0.05 M HCl to neutralize 345 mL of NaOH solution, what is the concentration of the NaOH solution?
0.0036 M
5.0 g of copper was heated from 20°C to 80°C. How much energy (in J) was used to heat Cu? (Specific heat of Cu is 0.092 cal/g°C)
120 J
Find the ΔH for the reaction below, given the following reactions and subsequent ΔH values:
2CO2(g) + H2O(g) → C2H2(g) + 5/2O2(g)
C2H2(g) + 2H2(g) → C2H6(g) ΔH=-94.5 kJ
H2O(g) → H2(g) + 1/2O2 (g) ΔH=71.2 kJ
C2H6(g) + 7/2O2(g) → 2CO2(g) + 3H2O(g) ΔH=-283 kJ
ΔH=235.1 kJ
Of the following gases, which one has density of 0.906 g/L at 315 K and 1.16 atm?
(a) Ne
(b) Ar
(c) Kr
(d) Xe
(e) He
a) Ne
352 mL of chlorine under a pressure of 680. mm Hg are placed in a container under a pressure of 1210 mm Hg. The temperature remains constant at 296 K. What is the volume of the container in liters?
198 mL
If it takes 54.0 mL of a 0.1 M NaOH solution to neutralize 125.0 mL of an HCl solution, what is the concentration of the HCl solution?
0.0432 M
50.0 g of iron that has an initial temperature of 225 oC and 50.0 g of gold that has an initial temperature of 25.0 oC are brought into contact with one another. Assuming no heat is lost to the surroundings, what will be the temperature when the two metals reach thermal equilibrium? The specific heat capacity of iron=0.449 J/goC and gold=0.128 J/goC.
181 oC
When 1.00 g of fructose, C6H12O6(s), is burned in oxygen in a bomb calorimeter, the temperature of the calorimeter increases by 1.58 °C. If the heat capacity of the calorimeter and its contents is 9.90 kJ/°C, what is qrxn (in kJ/mol) for this combustion?
-2.82 x 103 kJ
Calculate the density (in g/L) of C4H10 at 25°C and a pressure of 750 mmHg.
2.34 g/L
A sample of Krypton takes 43 seconds to effuse out of a container. An unknown gas take 59.4 s to effuse out of the identical container under identical conditions. What is the most likely identity of the unknown gas if we assume it is diatomic?
M= 159.9 g/mol
Bromine!