Thermochemistry & Energetics Of Chemical Reaction MDCAT Quiz: Focuses on heat changes in chemical reactions and energy transfer in the form of heat. The study of thermochemistry develops principles that enable the explanation of why a reaction occurs and how substances behave when they undergo a reaction. This is normally tested in most MDCAT Quiz questions on the enthalpy, entropy, and Gibbs free energy of chemical reactions.
Basics of Thermochemistry
Thermochemistry is the study of heat energy in chemical reactions. In any chemical reaction, energy is either absorbed or given off, and this energy change is reflected in the enthalpy (ΔH) of the system. In an exothermic reaction, heat is given off, and ΔH is negative; in an endothermic reaction, heat is absorbed, and ΔH is positive. Experimentally, enthalpy change may be found using calorimeters, and by using Hess’s Law, which states that the total enthalpy change in a reaction is the sum of the enthalpy changes of the individual steps. MDCAT Quiz questions often require students to apply Hess’s Law in calculating the overall enthalpy change of a reaction.
Energetics and Gibbs Free Energy
Energetics is the study of energy changes in chemical reactions, including the relation of enthalpy, entropy (ΔS), and temperature. The Gibbs free energy (ΔG) indicates whether a reaction is spontaneous or not. ΔG = ΔH – TΔS is the equation relating the quantities where T is the temperature in Kelvin. If ΔG is negative, the reaction is said to be spontaneous. One needs to understand this concept to answer MDCAT Quiz questions on the spontaneity and feasibility of a given reaction.
Applications of Thermochemistry in Chemical Reactions
The principles of thermochemistry and energetics can be applied to understand a wide range of chemical processes, including combustion, respiration, and industrial reactions. For example, the combustion of fuels is an exothermic reaction that gives out a large amount of energy. For MDCAT students, understanding the energetics of such reactions and how to calculate heat changes using calorimetry or other methods is important. Free Flashcard tools can be useful in memorizing key concepts such as enthalpy changes, entropy, and Gibbs free energy equations.
Get Your Username and Password for MDCAT Tests
Sign Up Now
Flashcard Thermochemistry & Energetics Of Chemical Reactions MDCAT Quiz
Mastering thermochemistry and the energetics of chemical reactions is critical to success on MDCAT due to questions covering heat changes and energy transfer in reactions. Using MDCAT Quiz and Free Flashcard resources, it will help solidify the learning of students so that they may enhance their capacity to solve any thermodynamic problem likely to come in the exam.
The first law of thermodynamics is also known as __________.
the law of energy conservation
The enthalpy change in a chemical reaction is represented by __________.
ΔHDelta HΔH
The enthalpy of formation of an element in its standard state is __________.
zero
The heat absorbed or released during a reaction at constant pressure is __________.
enthalpy change
The unit of enthalpy is __________.
joules
A process that absorbs heat is __________.
endothermic
The heat released during a reaction is called __________.
exothermic heat
The change in internal energy of a system is related to __________ in the first law of thermodynamics.
heat and work
The change in the enthalpy of a system can be calculated using __________.
Hess's Law
The entropy change for a reversible process is __________.
zero
The standard enthalpy of formation of a compound is the enthalpy change when one mole of a substance is formed from its elements in their __________.
standard states
A reaction in which the enthalpy decreases is __________.
exothermic
The Gibbs free energy is given by the equation G=H−TSG = H - TSG=H−TS, where H is __________.
enthalpy
For a reaction to be spontaneous at constant temperature, the change in Gibbs free energy must be __________.
negative
The heat of reaction at constant volume is equal to the change in __________.
internal energy
The heat capacity of a substance is the amount of heat required to __________.
change its temperature
The law of constant heat summation is also known as __________.
Hess's Law
The enthalpy of a reaction is the heat released or absorbed when __________.
the reaction occurs at constant pressure
The heat released by combustion is measured by __________.
a bomb calorimeter
The standard enthalpy of combustion refers to the enthalpy change when one mole of a substance reacts with __________.
oxygen
The specific heat capacity of water is __________.
4.18 J/g·°C
The total energy available for work in a thermodynamic system is represented by __________.
Gibbs free energy
If a process has a positive change in entropy, it means the process is __________.
spontaneous
In thermodynamics, the term ‘heat’ is often associated with __________.
enthalpy change
The energy required to break a bond is known as __________.
bond dissociation energy
The enthalpy change of a reaction can be determined from __________.
calorimetry
The entropy of a system is a measure of __________.
disorder
The heat released or absorbed during a phase transition is known as __________.
latent heat
When the temperature of a substance increases, the entropy of the substance __________.
increases
A system with a positive ΔSDelta SΔS and negative ΔHDelta HΔH will always be __________.
spontaneous
Experience the real exam environment with our expertly designed collection of over 25,000 MCQs MDCAT Mock Tests.
