Thermodynamics and State Changes

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Questions and Answers

What is the primary characteristic that distinguishes a solution from other types of mixtures?

Homogeneity at the particle level

Why is an alloy considered a mixture despite being a solid solution?

It shows the properties of its constituents and can have variable composition.

Provide an example of a gaseous solution mentioned in the text. Explain why it is considered a solution.

Air. It is considered a solution because it is a homogeneous mixture of gases.

How can it be determined that lemonade is a solution?

Lemonade tastes the same throughout, indicating that the particles of sugar or salt are evenly distributed. Signup and view all the answers

What is the approximate composition of brass, and why does this composition vary?

Brass is approximately 30% zinc and 70% copper. The composition can vary because it is a mixture, not a compound. Signup and view all the answers

Convert the following temperature to the Celsius scale: a. 300 K b. 573 K

a. 27°C b. 300°C Signup and view all the answers

What is the physical state of water at a. 250°C b. 100°C?

a. Gaseous b. Liquid Signup and view all the answers

For any substance, why does the temperature remain constant during the change of state?

The temperature remains constant because the energy is used to break the intermolecular bonds. Signup and view all the answers

Suggest a method to liquefy atmospheric gases.

Cooling followed by increasing pressure. Signup and view all the answers

Do we always need to heat or change pressure for changing the state of matter? Can you quote some examples from everyday life where change of state from liquid to vapour takes place without heating or changing pressure?

No. Examples include drying of wet clothes and evaporation of sweat. Signup and view all the answers

What is sublimation?

Sublimation is the change of state directly from solid to gas without changing into the liquid state. Signup and view all the answers

What happens to solid carbon dioxide when the pressure is decreased to 1 atmosphere?

Solid carbon dioxide gets converted directly into a gaseous state. Signup and view all the answers

How can a gas be liquefied?

A gas can be liquefied by applying pressure and reducing temperature. Signup and view all the answers

What term is used to describe the direct change of gas to solid without becoming a liquid?

Deposition. Signup and view all the answers

Name the process in which a liquid turns into a gas below its boiling point.

Evaporation. Signup and view all the answers

What factors affect the rate of evaporation?

Surface area, temperature, humidity, and wind speed. Signup and view all the answers

Describe what happens to the particles of a gas when pressure is applied.

The particles come closer together. Signup and view all the answers

Why is camphor used to demonstrate sublimation?

Camphor sublimates directly from solid to gas when heated. Signup and view all the answers

What observation would you make if you heated camphor under an inverted funnel with a cotton plug?

Camphor would sublime, depositing on the cooler parts of the funnel. Signup and view all the answers

How does wind speed affect evaporation?

Higher wind speed increases the rate of evaporation. Signup and view all the answers

Study Notes

Temperature Conversion

300 K is equivalent to 26.85°C
573 K is equivalent to 299.85°C

Physical State of Water

At 250°C, water is in the gaseous state
At 100°C, water is in the gaseous state

Change of State

Temperature remains constant during a change of state
Heat or change in pressure is not always necessary for a change of state

Sublimation and Deposition

Sublimation: direct change from solid to gas without changing into liquid state
Deposition: direct change from gas to solid without changing into liquid state
Examples: camphor, solid carbon dioxide (CO2) or dry ice

Factors Affecting the State of a Substance

Applying pressure and reducing temperature can liquefy gases
Pressure and temperature determine the state of a substance, whether it will be solid, liquid, or gas

Interconversion of the Three States of Matter

Sublimation: Solid to gas
Deposition: Gas to solid
Fusion: Solid to liquid
Solidification: Liquid to solid
Vaporization: Liquid to gas
Condensation: Gas to liquid

Factors Affecting Evaporation

Surface area: more surface area, higher the rate of evaporation
Temperature: higher the temperature, higher the rate of evaporation
Humidity: lower the humidity, higher the rate of evaporation
Wind speed: higher the wind speed, higher the rate of evaporation

Evaporation

Evaporation: change of liquid to gas at any temperature below boiling point
Particles with different kinetic energy overcome the forces of attraction of the liquid and get converted into vapour state
Examples: water left in an open dish, water in daily life

Solutions

A solution is a homogeneous mixture of two or more substances
Examples: lemonade, soda water, alloys, and air
Solutions can be liquid, solid (alloys), or gaseous (air)
In a solution, there is homogeneity at the particle level

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Description

Quiz on thermodynamics, covering temperature conversions, physical states of water, and methods to liquefy atmospheric gases.