Question

Select the FALSE statement from the following options:

Select one:

a. Internal energy is the sum of energies for all of the individual particles in a sample.

b. Energy cannot be created or destroyed.

c. Heat and temperature are two words that essentially mean the same thing.

d. The statement, ‘the total energy of the universe (system + surroundings) is constant’, is a logical extension of the law of conservation of energy.

e. Endothermic reactions can be spontaneous.\

If a system absorbs 55 J of heat and does 15 J of work, what is the value of ΔU for this change?

Select one:

+40 J

-40 J

+70 J

-70 J

How much heat will be released when 15.5 g of phosphorus reacts with excess chlorine according to the following equation?

2 P + 5 Cl₂ → 2 PCl₅    ∆H°= -886kJ

Select one:

a. -443 kJ

b. -886 kJ

c. -1772 kJ

d. -57.2 kJ

e. -222 kJ

A 500.0 g sample of aluminium, initially at 25.0 °C, absorbs heat from its surroundings and reaches a final temperature of 90.7 °C. How much heat (in kJ) has been absorbed by the sample? (specific heat = 0.9930 J g^–1 K^–1 for aluminum)

Enter your answer in kJ to one decimal place. Do not enter units.

Use the enthalpy of formation, ΔH°_f, values listed below to determine the enthalpy change for the following reaction:

2 H₂S_(g) + 3 O_2(g) → 2 H₂O_(l) + 2 SO_2(g)

Compound	ΔH°f (kJ/mol)
H2S(g)	-20.1
H2O(l)	-285.8
O2(g)	0.0
SO2(g)	-296.1

-1123.6 kJ

+1123.6 kJ

-561.8 kJ

+390.9 kJ

-602 kJ

Which one of the sets below has the species listed in order of increasing standard entropy?

Select one:

a. CaSO₄(s) < CH₃CH₂OH(l) < Kr(g) < CH₃CH₂Cl(g)

b. CH₃CH₂OH(l) < Kr(g) < CaSO₄(s) < CH₃CH₂Cl(g)

c. CaSO₄(s) < CH₃CH₂Cl(g) < CH₃CH₂OH(l) < Kr(g)

d. CaSO₄(s) < Kr(g) < CH₃CH₂OH(l) < CH₃CH₂Cl(g)

Using the following S^o values

H₂(g), S^o=130.6 J mol^-1 K^-1

C₂H₄(g), S^o=219.4 J mol^-1 K^-1

C₂H₆(g), S^o=229.5 J mol^-1 K^-1

calculate ΔS^o in J K^-1 for the reaction below.

C₂H₄(g) + H₂(g) → C₂H₆(g)

Enter your answer in J mol^-1 K^-1, to one decimal place. Do not enter units.

Answer:

Using the standard free energies of formation:

                  BaCO₃(s), Δ_f G^o = -1139.0 kJ mol^–1
                  BaSO₄(s), Δ_f G^o = -1353.0 kJ mol^–1
                  CO₂(g), Δ_f G^o = -394.4 kJ mol^–1
                  SO₃(g), Δ_f G^o= -370.0 kJ mol^–1

calculate the standard free energy change, ΔG^o, for the reaction:
BaCO₃(s) + SO₃(g) → BaSO₄(s) + CO₂(g)

Enter your answer in kJ mol^-1 to one decimal place. Do not enter units.

Calculate the standard free energy change, ΔG^o, for the reaction:
H_2(g) + I_2(s) → 2 HI_(g)

at 298K, given the following: ΔH^o_r =52.0 kJ/mol and ΔS^o_r = 165.3 J/mol

Select one:

+2.74 kJ/mol

+217.3 kJ/mol

-113 kJ/mol

+2830 kJ/mol