Physical Change and States of Matter

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Questions and Answers

What is the process called when liquid water turns into gas at the surface?

Evaporation

What force must be overcome for a particle to evaporate from the surface of a liquid?

Air pressure

What is the opposite process of melting, and what does it involve?

Freezing, which involves the change of state from liquid to solid.

Define condensation and mention how it relates to the energy of gas particles.

Condensation is the removal of thermal energy from a gas to form a liquid. Signup and view all the answers

How does the temperature of a substance behave during boiling?

The temperature remains at the boiling point until all particles change to gas. Signup and view all the answers

What role does thermal energy play in the freezing process?

Thermal energy removal causes particles in a liquid to slow down and bond into a solid structure. Signup and view all the answers

Explain how the energy of particles affects their ability to overcome attractive forces.

Higher energy allows particles to overcome attractive forces and change state. Signup and view all the answers

What happens to water vapor particles as they cool down and condense?

They lose thermal energy, move slower, and cannot overcome attractions to form a liquid. Signup and view all the answers

Can the boiling and freezing points of a substance be affected by pressure? Provide a brief explanation.

Yes, changes in pressure can alter boiling and freezing points. Signup and view all the answers

What is the significance of the term 'boiling point' in the context of phase changes?

The boiling point is the temperature at which a liquid's vapor pressure equals the external pressure. Signup and view all the answers

What type of change occurs when baking a cake?

A chemical change. Signup and view all the answers

What is the process called when a solid changes directly into a gas?

Sublimation. Signup and view all the answers

How does thermal energy affect the state of matter?

It changes the arrangement and spacing of particles. Signup and view all the answers

During a change of state, what happens to the mass of the matter?

The total mass remains unchanged. Signup and view all the answers

Which of the following is classified as a reversible change: rusting of iron or melting of ice?

Melting of ice. Signup and view all the answers

What causes particles in a substance to speed up during melting?

An increase in thermal energy. Signup and view all the answers

What is the term for the change in state from a liquid to a gas occurring at the surface?

Evaporation. Signup and view all the answers

Which change in state corresponds to the release of thermal energy?

Condensation. Signup and view all the answers

What happens to the spacing of particles during freezing?

Particles come closer together. Signup and view all the answers

Which physical change does not alter the identity of the substance?

Cutting a paper. Signup and view all the answers

Study Notes

Physical Change

A physical change alters one or more physical properties of a substance, but the substance's identity remains the same.
Examples include changes of state, dissolving, and cutting.

Examples of Physical Changes

Water turning into ice
Baking a cake
Cutting a paper
Folding clothes
Water droplets on a cooking pan lid

Examples of Changes that are Not Physical Changes

Burning a match
Frying an egg
Rusting of iron
A green tomato turning red

Changing States of Matter

Changing the state of matter involves transferring energy.
Thermal energy is involved in changing the state of matter
Examples include melting, freezing, evaporation, condensation, and sublimation.

Processes of Changing State

Melting: The change from solid to liquid. Energy is required.
Freezing: The change from liquid to solid. Energy is released.
Evaporation: The change from liquid to gas. Energy is required.
Condensation: The change from gas to liquid. Energy is released.
Sublimation: The change from solid directly to gas. Energy is required.

What Happens During a Change of State?

The number of particles does not change during a change of state.
The total mass of matter does not change during a change of state.

Melting (Detailed)

During melting, adding thermal energy causes particles to speed up.
Particles break away from the fixed positions of the solid, becoming more spaced out, in a liquid state.
The melting point is the temperature at which this occurs, remaining constant until all of the solid changes to liquid.

Boiling (Detailed)

Boiling is when vaporization occurs throughout the liquid.
A substance will maintain a constant temperature at its boiling point until all the liquid particles are in gas state.
The bubbles formed at the boiling point contain water vapor, a gas.

Evaporation (Detailed)

Evaporation happens at the surface of a liquid.
Particles at the liquid surface gain enough energy to overcome attractive forces to other particles in the liquid and enter the gaseous state.
Pressure also plays a role; particles need to overcome atmospheric pressure to fully evaporate.

Freezing (Detailed)

Freezing reverses melting.
Removing thermal energy slows particles.
Particles lose energy and move closer together, organizing in a fixed position in the solid state.
The freezing point is when liquid converts to solid.

Condensation (Detailed)

Reverses evaporation.
Removing energy from gaseous particles slows them down.
Particles move closer together, forming stronger attractive forces that create the liquid state.

Change of State Diagram

The diagram shows how temperature changes during a change of state.
Note the stable horizontal lines at the specific point during phase transition, which shows the stable thermal energy state during a change of matter state.

Reversible or Irreversible?

Changes of state are generally reversible, meaning one can typically return substances to their original state.

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Description

This quiz explores the concept of physical changes and the different states of matter. Understand how energy transfer plays a role in these changes and identify examples of both physical changes and changes that are not physical. Test your knowledge on processes like melting, freezing, evaporation, and condensation.