HGC 1201 ▬ GENERAL CHEMISTRY 2 ▬ Q3 - QUIZ3

Which of the following is an exothermic reaction?

• Sublimation of Naphthalene (C10H8)

• Melting of Iron (F)

• Vaporization of Methanol (CH3OHM

• Combustion of Acetylene (C2H2)

Which of the following is defined as the "heat change that takes place when 1 mole of a compound is formed from its elements in their stable states at standard temperature and pressure"?

• standard enthalpy of formation

• standard enthalpy of hydration

• standard enthalpy of atomization

• standard enthalpy of combustion

The standard temperature and pressure is given at which of the following values?

• 25 degrees Celsius, 760 atm

• 25 degrees Celsius, 2 atm

• 25 degrees Celsius, 1 atm

• 1 degree Celsius, 25 atm

The change in enthalpy of reaction can be defined as ____.

• ΔHproducts +ΔHreactants

• ΔHproducts x ΔHreactants

• ΔHreactants + ΔHproducts

• ΔHproducts - ΔHreactants

Which of the following thermochemical equation is an example that exhibits combustion?

• 2C3H8O + 9O2 → 6CO2 + 8H2O

• C3H8O + H2O → CO2 + O2

• C3H8O + NO2 → CO2 + N2O

• C3H8O + CO2 → 2CO2 + H2O

A thermochemical equation shows that the resulting change in enthalpy is ΔH=-78kJ. What can we conclude from the value of the change in enthalpy?

• the reaction is endothermic

• the products are solid metallic oxides

• the reactants are volatile

• the reaction is exothermic

Combustion of hydrocarbons are extremely exothermic reactions. which of the following is a by-product of combustion of hydrocarbons

• aqueous carboxylic acids

• metallic oxides and water

• carbon dioxide and water

• aromatic phenols

This physical law states that: regardless of the multiple stages or steps of a reaction, the total enthalpy change for the reaction is the sum of all changes.

• Law of conservation of energy

• First law of thermodynamics

• Hess's law

• Calvin cycle

Consider the following reactions below:

S(s) + 1/2 O2(g) → SO(g)              ΔH° = -140.0  kJ

SO2(g)  → SO(g) + 1/2 O2(g)         ΔH° = 295.5 kJ

Calculate ΔH° for the reaction: S(s)  + O2(g)  →  SO2(g)

• 435.5 kJ

• 155.5 kJ

• -435.5 kJ

• -155.5 kJ