4.13 Chemical Thermodynamics

Question: Which example is an exothermic reaction?

Answer: condensation

Question: Two objects (A and B) of the same temperature are in contact with each other.

Which statement is true?

Answer: Although the molecules collide, no heat transfers because there is no temperature difference between the objects

Question: Which parameter is measured directly in a coffee-cup calorimeter?

Answer: temperature

Question: Which type of substance would be best for use in a cooling system?

Answer: a liquid with a high specific heat

Question: The reaction 2NO (g) → N2 (g) + O2 (g) has a ΔH =−180.5 kJ .

How much heat will be required to produce 44.8 L of NO by the reverse reaction?

Answer: 180.5 kJ

Question:

Answer: 2nd one

In an exothermic reaction, the energy of the products is less than the energy of the reactants.

Question: Which statement is a correctly written thermochemical equation?

Answer: 4Fe (s) + 3O2 (g)→2Fe2O3 (s), ΔH = −3,926 kJ

Question: What is likely to be true about the ΔH for this reaction?

C6H6 (s) → C6H6 (l)

Answer: ∆H > 0

Question: Two hundred grams of a substance requires 1.84 kJ of heat to raise its temperature from 25°C to 45°C.

Use the table to identify the substance.

q=mCΔT.

Mass (m) is in grams. Temperature is in degrees Celsius.

Answer: iron

Question: A chemical reaction is carried out in a closed container. The energy absorbed by the chemical reaction is 200 kJ.

What is the energy liberated from the air or the walls of the container?

Answer: 200 kJ