# Worksheet: Enthalpy and Internal Energy

In this worksheet, we will practice calculating enthalpy changes from changes in internal energy and changes in volume, at constant pressure.

Q1:

A 1.50 mol sample of an ideal gas at 245 K and a pressure of 0.75 bar is altered by some process that takes it to a state in which its temperature is increased to 295 K and its pressure is increased to 0.90 bar. What will the enthalpy change of the gas in this process be?

Q2:

Consider the shown reaction, for which the standard reaction enthalpy has a value of at a temperature of 298 K. What is the value of for this reaction at ?

Q3:

Consider the shown reaction, for which the standard reaction enthalpy is . Calculate the value of for this reaction and determine whether any thermodynamic work is done on or by the reaction system if the reaction is carried out at a constant pressure. Assume that the gases in this reaction exhibit ideal gas behavior at and .

• A and
• B and
• C and
• D and
• E and

Q4:

The standard heat of combustion of solid glucose at 298 K is . What is the value of , the change in internal energy accompanying the combustion at 298 K and a fixed pressure of 1 bar?