Chemistry XII Unit 5 Questions: 50 Time Limit: 50 minutes Passing Score: 60% Start Quiz Chemistry XII Unit 5 Question 1 of 50 What is thermodynamics? Study of motion Study of energy transformations Study of atoms Study of reactions What is a system? Surroundings Part of universe under investigation Boundary Entire universe What are surroundings? System itself Everything outside the system Boundary Universe What is an open system? Exchanges both energy and matter with surroundings Exchanges only energy Exchanges only matter No exchange What is a closed system? Exchanges both energy and matter Exchanges only energy not matter Exchanges only matter No exchange at all What is an isolated system? Exchanges energy only Exchanges matter only Exchanges both Neither energy nor matter exchange What is internal energy (U)? Sum of all forms of energy in system Kinetic energy only Potential energy only Heat energy only What is the first law of thermodynamics? Energy cannot be created or destroyed Entropy increases Heat flows from hot to cold Energy becomes unavailable What is the mathematical form of first law? Delta U equals q plus w Delta U equals q minus w Delta U equals q times w Delta U equals w minus q What is sign convention for heat absorbed by system? Negative Zero Positive Can be both What is sign convention for work done by system? Positive Negative Zero Can be both What is enthalpy (H)? U plus P times V U minus P times V U times P times V U divided by P times V What is Delta H? Heat absorbed at constant pressure Heat absorbed at constant volume Work done Internal energy change What is exothermic reaction? Absorbs heat, Delta H positive Releases heat, Delta H negative No heat change Absorbs light What is endothermic reaction? Releases heat, Delta H negative Absorbs heat, Delta H positive No heat change Releases light What is standard enthalpy of formation? Enthalpy change when 1 mole of compound formed from elements in standard states Enthalpy of reaction Enthalpy of combustion Enthalpy of solution What is standard enthalpy of combustion? Enthalpy change when 1 mole of substance completely burns in oxygen Enthalpy of formation Enthalpy of solution Enthalpy of neutralization What is Hess's law? Total enthalpy change is same whether reaction occurs in one or multiple steps Energy is conserved Entropy increases Pressure is constant What is the formula for enthalpy of reaction using Hess's law? Delta r H equals sum of Delta f H products minus sum of Delta f H reactants Delta r H equals sum of products plus reactants Delta r H equals products times reactants Delta r H equals reactants divided by products What is bond enthalpy? Enthalpy change when 1 mole of bonds broken in gaseous state Energy to form bond Energy of reaction Energy of formation What is lattice enthalpy? Enthalpy change when 1 mole of ionic solid forms from gaseous ions Enthalpy of solution Enthalpy of fusion Enthalpy of vaporization What is enthalpy of solution? Enthalpy change when 1 mole of solute dissolves in solvent Enthalpy of reaction Enthalpy of formation Enthalpy of fusion What is enthalpy of neutralization? Enthalpy change when 1 equivalent of acid neutralizes 1 equivalent of base Enthalpy of solution Enthalpy of formation Enthalpy of combustion What is the value of enthalpy of neutralization for strong acid and strong base? Minus 13.7 kcal per equivalent Plus 13.7 kcal per equivalent Minus 57.1 kJ per mol Both 1 and 3 What is entropy (S)? Measure of randomness or disorder Measure of energy Measure of temperature Measure of pressure What happens to entropy when solid melts to liquid? Decreases Remains same Increases Becomes zero What happens to entropy when liquid vaporizes to gas? Decreases Remains same Increases significantly Becomes zero What is the second law of thermodynamics? Energy is conserved Entropy of universe increases in spontaneous process Heat flows from cold to hot Enthalpy decreases What is Delta S for universe? Delta S system plus Delta S surroundings Delta S system minus Delta S surroundings Delta S system times Delta S surroundings Delta S system only For spontaneous process, Delta S universe is: Negative Zero Positive Can be any value What is Gibbs free energy (G)? H minus T times S H plus T times S U minus T times S U plus T times S What is Delta G? Change in Gibbs free energy Change in enthalpy Change in entropy Change in temperature For spontaneous process at constant temperature and pressure, Delta G is: Positive Zero Negative Infinite At equilibrium, Delta G is: Positive Negative Zero Infinite What is the relation between Delta G, Delta H and Delta S? Delta G equals Delta H minus T times Delta S Delta G equals Delta H plus T times Delta S Delta G equals Delta H times Delta S Delta G equals Delta H divided by T times S When Delta G is negative, reaction is: Non-spontaneous At equilibrium Spontaneous Reversible When Delta G is positive, reaction is: Spontaneous Non-spontaneous At equilibrium Reversible What is standard free energy change? Free energy change when all species are in standard states Free energy at equilibrium Free energy of formation Free energy of reaction What is the relation between Delta G degree and equilibrium constant? Delta G degree equals minus RT ln K Delta G degree equals RT ln K Delta G degree equals K times RT Delta G degree equals R divided by T times K What is the formula for work done in expansion? w equals minus P external times Delta V w equals P times V w equals P divided by V w equals V divided by P What is heat capacity? Heat required to raise temperature by 1 degree Heat required to melt substance Heat required to vaporize Heat required to form compound What is specific heat capacity? Heat capacity per unit mass Heat capacity per mole Total heat capacity Heat capacity of 1 kg What is molar heat capacity? Heat capacity per unit mass Heat capacity per mole Total heat capacity Heat capacity of 1 gram What is Cp? Heat capacity at constant pressure Heat capacity at constant volume Specific heat capacity Molar heat capacity What is Cv? Heat capacity at constant pressure Heat capacity at constant volume Specific heat capacity Total heat capacity What is the relation between Cp and Cv for ideal gas? Cp minus Cv equals R Cp plus Cv equals R Cp times Cv equals R Cp divided by Cv equals R What is calorimetry? Measurement of heat changes Measurement of pressure Measurement of volume Measurement of temperature What is bomb calorimeter used for? Measuring enthalpy of combustion Measuring enthalpy of formation Measuring enthalpy of solution Measuring entropy What is spontaneous process? Process that occurs on its own without external help Process requiring energy input Process at equilibrium Process that never occurs What is the third law of thermodynamics? Entropy of perfect crystal at absolute zero is zero Energy is conserved Entropy increases Enthalpy is constant Previous Next Submit Quiz Want to save your progress? Create an account or log in to track your quiz scores! Register/Login