Conceptual
Calorimetry
Enthalpy
Completely Unrelated
100
The enthalpy of formation for pure elements (Na, O2, etc.) is _________ kJ/mol.
0 kJ/mol
100
The unit for heat energy that you see every single day is the __________.
Calorie (or kilocalorie)
100
What is the sign of ΔH for endothermic and exothermic reactions?
Endothermic is +ΔH
Exothermic is -ΔH
100
Most people living in Australia are descended from the ancestors of which country?
England/Britain/UK
200
Why does something feel cold to the touch?
The object is pulling heat away from you. (endothermic from the perspective of the object; exothermic from your perspective)
200
What is the ΔT for an object that is initially at -20 °C and ends at 75 °C?
95 oC
200
Describe the enthalpy change for melting.
The enthalpy change for melting is positive because melting is an endothermic process.
200
What percent of Gen Z believes that they will never be able to own a home? (within 3% will be counted correct).
82%
300
In the context of Hess's Law, what does the Σ mean?
"The sum of", specifically, the enthalpy of formation values for either all of the products or all of the reactants, depending on the term.
300
In the formula q = mcΔT, what are the units for each variable?
q --> Joules
m --> grams
c --> J/goC
T --> Celsius
300
Explain what kJ/mol means in the context of molar enthalpy.
Ex:
2H2 + O2 --> H2O + 483.6 kJ/mol
kJ/mol tells the amount of heat released in kJ per mole of substance reacted.
So, in the above example, 1 mol of O2 reacted produces 483.6 kJ of heat.
300
What currency does this symbol represent?
Japanese Yen
400
Why do things at different temperatures eventually equalize?
Heat naturally flows from hotter substances to colder substances, as fast particles collide with slower particles. This continues until the particles of both substances reach thermal equilibrium.
400
What do the units for Specific Heat mean? (J/goC)
The amount of energy (heat) required to raise 1 gram of a substance by 1 degree Celsius.
400
Water condensates on the exterior of a cold bottle of soda. Is this endothermic or exothermic and why?
Exothermic. The water is transitioning from a gas (higher energy) to a liquid (lower energy). Therefore, the excess energy is released from the water.
400
The most common material for clothing is _____________________.
Polyester (derived from petroleum/plastic)
500
Why is this reaction endothermic?
NH4NO3 --> NH4+ + NO3-
Breaking bonds requires energy input.
500
What is the mass of a piece of aluminum (c = 0.9 J/goC) if it absorbs 200 J of heat and increases in temperature by 20 oC?
11.11 g.
500
What is the enthalpy change for the following reaction?
2C2H6 + 7O2 --> 4CO2 + 6H2O
ΔHf values:
C2H6 = -84.7 kJ/mol
O2 = 0
CO2 = -393.5 kJ/mol
H2O = -285.8 kJ/mol
~-3,119.4 kJ/mol
500
What country is closest in size to the continental US?
Australia