ECAT MCQs

Particles move from regions of higher concentration toward lower concentration.
Diffusion occurs in gases, liquids, and solids.

Dalton's law adds partial pressures.
20+35+45 = 100 kPa.

Effusion rates depend on molar mass.
Lighter gases generally effuse faster.

Moles equal molarity times volume in liters.
0.50×2.0 = 1.0 mol.

Crystalline solids have repeating lattice structures.
They often have sharp melting points.

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

Glass is a common amorphous solid.
Such solids often soften over a temperature range.

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

The solvent is usually the component in larger amount.
The solute is dispersed at the molecular or ionic level.

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

Solubility depends on temperature and the nature of solute and solvent.
For gases, pressure also matters.

A saturated solution is in equilibrium with undissolved solute.
Additional solute will not dissolve under unchanged conditions.