Learning Modules 49-54

You purchase a chilled bottle of water at the convenience store. Over time it absorbs energy and
warms up. What kind of system is it and where did the heat come from to warm it up?

• Closed system, surroundings

• Open system, system

• Open system, surroundings

• Closed system, universe

Tags

NGSS.HS-PS3-4

Which of the state functions are related to the first law of thermodynamics?

• E and H

• E and G

• S and E

• All of them

Tags

NGSS.HS-PS3-1

NGSS.HS-PS3-2

For the freezing of water
H2O(l) ⟶ H2O(s)
What are the signs of ΔH and ΔS?

• – and –

• + and +

• + and -

• - and +

Enthalpy is related to internal energy in what way?

• They differ only by PV

• They are the same thing

• Enthalpy is heat and internal energy is work

• Enthalpy is free energy not internal energy

The formal definition of enthalpy is:
H = U + PV
This shows that enthalpy is equal to the combined internal energy and work, which
is shown here as PV.
2. What is the temperature change if 400 J of energy is added to 10 grams of water?

• 10 degrees Celsius
  

• 100 degrees Celsius

• 1 degree Celsius

• 40 degrees Celsius

Tags

NGSS.HS-PS3-1

Three metals, A, B and C, of equal mass, have heat capacities of 0.3 J/goC, 0.4
J/goC, and 0.5 J/goC, respectively. Which of these metals will have the largest increase in temperature if the same amount of heat is added to the each of their
systems?

• A

• C

• not enough information

• same amounts of mass means same temperature change

100 kJ of energy is introduced to your cell phone while it charges but 10 kJ of
energy is lost in the process as heat given off to the surroundings. What is E for
the system?

• +90 kJ

• +110 kJ

• -90 kJ

• -110 kJ

Tags

NGSS.HS-PS3-1

Consider the explosion of a hydrogen balloon.
2H2(g) + O2(g) → 2H2O(g)
How much work is done and is it on or by the system?

• +2.5 kJ

• -2.5 kJ

• +7.5 kJ

• -7.5 kJ

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-1

Suppose ethanol is used instead of water as the solvent in the container surrounding the
system. If ethanol has a heat capacity that is about half that of water, what will change in
the calorimetry calculation?

• The change in temperature of the surroundings will double.

• There will be no change in the calculation.

• The change in temperature of the surroundings will be half that if water is used.

• The change in temperature of the surroundings will be a fourth that if water is used.

Tags

NGSS.HS-PS3-4