Physical Transformations and Phase Diagrams Quiz

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Questions and Answers

Which term refers to a form of matter that is uniform throughout in chemical composition and physical state?

Phase (correct)

Phase transition

Metastable phase

Phase boundary

What is the term for the temperature at which two phases are in equilibrium and the Gibbs energy is minimized at the prevailing pressure?

Thermodynamic temperature

Equilibrium temperature

Transition temperature (correct)

Phase stability temperature

What does a phase diagram show?

Chemical reactions of a substance

Vapour pressure variation with temperature

Melting point variation with pressure

Physical changes of state that a substance can undergo (correct)

What are metastable phases?

Thermodynamically unstable phases that exist because the transition to a more stable phase is kinetically hindered Signup and view all the answers

What do phase boundaries on a phase diagram represent?

Regions of pressure and temperature where solid, liquid, or gas is stable with minimum molar Gibbs energy Signup and view all the answers

What does a phase diagram map?

Physical changes of state that a substance can undergo Signup and view all the answers

Which temperature is at the point where the surface disappears and a single uniform phase called a supercritical fluid appears?

Critical temperature Signup and view all the answers

What is the pressure at the critical temperature known as?

Critical pressure Signup and view all the answers

At what pressure is the standard boiling point of a liquid slightly lower than its normal boiling point?

1 bar Signup and view all the answers

What does the positive slope of the solid-liquid boundary in carbon dioxide indicate?

Increasing melting temperature with increasing pressure Signup and view all the answers

At what triple point condition do three different phases of a substance (typically solid, liquid, and vapor) coexist in equilibrium?

$T_{3}$ Signup and view all the answers

At what pressure does the liquid phase of carbon dioxide sublimate regardless of the temperature?

$1$ atm Signup and view all the answers

What is the temperature at which the vapor pressure of a liquid is equal to the external pressure known as?

Boiling point Signup and view all the answers

What occurs at no other combination of pressure and temperature?

$T_{3}$ Signup and view all the answers

What is the characteristic behavior indicated by the positive slope of the solid-liquid boundary in carbon dioxide?

$CO_{2}$ melting temperature increases with increasing pressure Signup and view all the answers

At what pressure is it necessary to exert to obtain liquid carbon dioxide at any temperature?

$5.11$ atm Signup and view all the answers

Study Notes

Terms and Definitions

A homogeneous substance is a form of matter that is uniform in chemical composition and physical state.
The Gibbs energy is minimized and in equilibrium at the temperature where two phases co-exist, known as the phase equilibrium temperature.

Phase Diagrams

A phase diagram visually represents the different phases of a substance under varying temperature and pressure conditions.
Metastable phases are states that are stable under certain conditions, but not in the lowest energy state possible.
Phase boundaries on a phase diagram indicate the conditions (temperature and pressure) at which two phases coexist.

Additional Concepts

A phase diagram maps the stability of phases under different temperature and pressure conditions.
Supercritical fluid occurs at the critical temperature, where the distinction between liquid and gas phases disappears.
The critical pressure is the pressure exerted at the critical temperature.

Boiling Points and Pressure Conditions

At a lower pressure than the normal boiling point, the standard boiling point for a liquid is slightly lower.
The positive slope of the solid-liquid boundary in carbon dioxide signifies that solid CO2 (dry ice) converts to liquid under increased pressure.

Triple Points and Sublimation

At the triple point condition, solid, liquid, and vapor phases coexist in equilibrium.
The liquid phase of carbon dioxide sublimates at any temperature under a pressure lower than its triple point pressure.

Vapor Pressure and Temperature Relations

The temperature at which vapor pressure equals external pressure is known as the boiling point.
Unique phase behavior occurs at no other combination of pressure and temperature, indicating specific stability conditions.

Pressure Conditions for CO2

To obtain liquid carbon dioxide at any temperature, a pressure greater than the triple point pressure is necessary.

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Description

Test your knowledge of physical transformations of pure substances, phase boundaries, phase stability, phase transitions, and liquid surfaces, as well as phase diagrams for one-component, two-component, and three-component systems. Explore the map of pressures and temperatures at which each phase of a substance is most stable and understand the physical changes of state that a substance can undergo.