1st Law of Thermodynamics

The Law of Conservation of Energy is also known as...

• First Law of Thermodynamics

• Second Law of Thermodynamics

• Third Law of Thermodynamics

• Newton's First Law

Given the hypothetical thermochemical equation:

A + B → C + D ΔH = -430 kJ/mol

Which among the following statements is correct about this reaction?

• The reaction is exothermic.

• The heat content of C and D is greater than the heat content of A and B.

• The heat content of A and C is greater than the heat content of B and D.

A reaction is allowed to take place in an insulated container containing 100mL of water. If the reaction is endothermic, what happens to the temperature of water?

• The temperature of the water goes down.

• The temperature of the water goes up.

• The temperature of the water does not change.

• None of the above.

Which of the following does NOT describe an endothermic reactions?

• absorption of energy

• ΔH > 0

• H_reactant < H_product

• -ΔH

ΔH is expressed in units of

• cal

• kJ/mol

• J

• kcal

Solving for ΔH involves

• Reversing all given chemical reactions.

• Manipulating the equation so that the reactants and products are on the desired side of the equation

• Change the sign of ΔH

• Removing all reactants that are on the same side of the equation

If the ΔH for 3S(s) + 4½O₂(g) → 3SO₃(l) is -922 kJ/mol.

A. What is the ΔH for this reaction: 6SO₃(l) → 6S(s) + 9O₂(g) ΔH = ?

B. What kind of reaction is it?

Determine ΔH for the reaction:

ClF(g) + F₂(g) → ClF₃(g) ΔH=?

Given the following reactions:

2OF₂(g) → O₂(g) + 2F₂(g) ΔH= -49.4 kJ/mol

2ClF(g) + O₂(g) → Cl₂O(g) + OF₂(g) ΔH= +214 kJ/mol

ClF₃(g) + O₂ → ½Cl₂O(g) + 1½OF₂(g) ΔH= +236.2 kJ/mol