Progress Check 6.4 -->6.6

The graph above shows the changes in temperature recorded for the 2.00 L H₂O surrounding a constant-volume container in which a 1.00 g sample of benzoic acid was combusted. Assume that heat was not absorbed by the container or lost to the surroundings, that the density of H₂O is 1.00g/mL, and that the specific heat capacity of H₂O is about 4.2J/g⋅°C. Based on this information, estimate how much heat was released from the combustion of the benzoic acid sample.

• 0.013kJ

• 25kJ

• 180kJ

• 210kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4

For an experiment, a 20.0 g piece of Al was placed inside an insulated cup filled with 40.0 g of H₂O. The data are given in the table above. Assuming no heat is absorbed by the container or the surroundings, which of the following equations provides the correct mathematical relationship for the transfer of heat q between Al and H₂O?

• −qAl=12×qH₂O

• -qAl=6×qH₂O

• −qAl=2×qH₂O

• −qAl=qH₂O

Tags

NGSS.HS-PS3-4

A student dissolves 8.00 g of NH₄NO₃(s) in 100. g of H₂O(l) in a coffee-cup calorimeter. Based on the initial and final temperatures of the mixture in degrees Celsius shown in the diagram above the laboratory setup, what is the calculated ΔT of the water reported to the appropriate number of significant figures?

• −5.500°C

• −5.50°C

• −5.5°C

• −6°C

Tags

NGSS.HS-PS3-4

Particulate models of the evaporation of liquid water and the condensation of water vapor are shown above. Based on these models, which of the following accurately compares the energy changes associated with each of the phase changes?

• The amount of energy absorbed by one mole of water molecules as they escape the liquid is greater than the amount of energy released by one mole of water molecules as they come together to form a liquid.

• The amount of energy absorbed by one mole of water molecules as they escape the liquid is less than the amount of energy released by one mole of water molecules as they come together to form a liquid.

• The amount of energy absorbed by one mole of water molecules as they escape the liquid is equal to the amount of energy released by one mole of water molecules as they come together to form a liquid.

• The amount of energy absorbed by one mole of water molecules escaping the liquid can be either greater than or less than the amount of energy released by one mole of water molecules as they come together.

The table above provides the values for some physical properties of H₂S and H₂O. Approximately, how many moles of H₂S must be condensed to release as much heat as would be released when 1 mole of H₂O is condensed?

• 0.5 mole of H₂S

• 1 mole of H₂S

• 2 moles of H₂S

• 4 moles of H₂S

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4

The heating curve for 1.0 mole of Na, initially at 25.0°C, is shown above at the left. Which of the following best explains the change in heat when 0.50 mole of Na

Na undergoes the transition shown in the diagram above to the right?

• Approximately 13kJ of heat are absorbed as a result of the increase in potential energy between the Na atoms

• Approximately 49kJ of heat are absorbed to overcome the attractive forces acting between Na atoms.

• Approximately 98kJ of heat are released as a result of the decrease in the kinetic energy of the NaNa atoms

• Approximately 120kJ of heat are released to decrease the potential energy between Na atoms.

Tags

NGSS.HS-PS3-4

Na₂S₂O₃(aq)+4NaOCl(aq)+2NaOH(aq)→2Na₂SO₄(aq)+4NaCl(aq)+H₂O(l)

The enthalpy change for the reaction represented by the chemical equation shown above is ΔH°=−1236kJ/molrxn. When 2.00mol of NaOCl(aq) reacts completely with an excess of Na₂S₂O₃(aq) and of NaOH(aq)), which of the following enthalpy changes occurs?

• 618kJ of heat is absorbed.

• 2470kJ of heat is absorbed.

• 618kJ of heat is released.

• 2470kJ of heat is released.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

2Al(s)+Fe₂O₃(s)→2Fe(s)+Al₂O₃(s) ΔH°=−850kJ/molrxn

The chemical equation shown above represents the thermite reaction. What is the approximate amount of heat released when 108g of Al(s) reacts with excess Fe₂O₃(s)?

• 210kJ

• 430kJ

• 850kJ

• 1700kJ

Tags

NGSS.HS-PS3-1

2CO(g)+C(g)→C₃O₂(g) ΔH°=127.3kJ/molrxn

The equation shown above represents an endothermic reaction between CO(g) and C(g). What is the amount of heat absorbed when 1.00mol of CO(g) reacts with an excess C(g) ?

• 31.8kJ

• 63.7kJ

• 127.3kJ

• 254.6kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

If 100 g of aluminum at 145ºC gains 6,800 J of heat, what is the final temperature (T_final) of the aluminum? Aluminum has a specific heat of 0.897 J/gºC. (Q=mcΔT)

• -69°C
• 0.52°C
• 221°C

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-4