MDCAT Chemistry MCQs

Higher pressure favors the side occupying less gas volume.
That is usually the side with fewer gas moles.

Energy may be transferred as heat or work.
It is not created or destroyed.

A catalyst lowers activation energies for both directions.
It speeds equilibration without changing the equilibrium position.

Greater dispersal and more possible arrangements generally mean higher entropy.
Gases usually have higher entropy than liquids or solids.

Temperature alters the balance between forward and reverse energetics.
K is constant only at a specified temperature.

The system may be a reaction mixture, gas, or other selected matter.
Everything else is called the surroundings.

The surroundings can exchange energy or matter with the system depending on the boundary.
System plus surroundings form the universe.

Open systems allow material flow across their boundaries.
Many industrial reactors are open systems.

A closed system has fixed mass.
Heat or work may still cross its boundary.

An ideal isolated system has no interaction with surroundings.
A perfect thermos is an approximate example.

Internal energy includes molecular motion, bonding, and interactions.
Only changes in internal energy are directly measured.

Enthalpy is H=U+PV.
At constant pressure, enthalpy change equals heat transferred for PV work.