Warm-up Wet floor is left to dry up. Are these examples of evaporation? Feeling cool under air-conditioner. Ironing wet clothes to dry them.

Slides:



Advertisements
Similar presentations
What is Weather?.
Advertisements

Change of State. The 3 Basic States of Matter What about Plasma?
Investigating the Temperature of Air
Why should crushed ice be used in the experiment? To increase the surface area of ice and keep good contact with the heater. Crushed ice should be used.
Change of Phase Evaporation Condensation Fogs and Clouds Boiling Melting and Freezing Energy and Change of Phase.
Change of Phase (state) SolidLiquidGas SolidXmeltingsublimation LiquidfreezingXevaporation Gas “anti- sublimation” deposition condensationX.
Chapter 23 – change of phase
Evaporation & Condensation Noadswood Science, 2011.
Last lesson?. Thermal capacity Thermal capacity is the amount of energy needed to raise the temperature of a substance by 1K.
Discover PHYSICS for GCE ‘O’ Level Science
HOW IS KINETIC ENERGY DISTRIBUTED IN A LIQUID?.
Physical and Chemical Changes
Change of Phase (state) SolidLiquidGas SolidXmeltingsublimation LiquidfreezingXevaporation Gas “anti- sublimation” deposition condensationX.
Humidity and Condensation Water is unique because it is the only substance that commonly exists in all ____________________________ of matter. Depending.
SECTION 2: CHANGES OF STATE Chapter 2: Solids, Liquids, and Gases.
1.3 Change of State Change of State
BASIC PRINCIPLES OF HEAT & COLD. How the Body Produces Heat All food & drinks contain Calories A Calorie is the heat value of food Calories in the body.
State Changes How matter changes forms. What is energy?  Energy is the ability to do work or cause change.
State Changes How matter changes forms. What is energy?  Energy is the ability to do work or cause change.
State Changes How matter changes forms. What is energy?  Energy is the ability to do work or cause change.
State Changes How matter changes forms Physical Science.
2 pt 3 pt 4 pt 5 pt 1 pt 2 pt 3 pt 4 pt 5 pt 1 pt 2 pt 3 pt 4 pt 5 pt 1 pt 2 pt 3 pt 4 pt 5 pt 1 pt 2 pt 3 pt 4 pt 5 pt 1 pt HUMIDITY LATENT HEAT WATER.
Water in the Air It’s always there. Water is ALWAYS in the Air! It can be in the air as a solid, a liquid or a gas. Solid- Ice Liquid- Water Gas- Water.
Earth Science Intro Unit
Evaporation works like this
Humidity. Remember: Water takes longer to warm and cool because of its high heat capacity. Lots of solar energy is needed to change the state of water!
Thermodynamics Jillian Campbell, Karly Johnson, Jared O, Daniel.
Changes of State Name:. Change of State  The particles of a substance move differently depending on the state of the substance. The particles also have.
1 Lesson 02: Humidity: Water in the Air Pages
© 2009 Marshall Cavendish International (Singapore) Private Limited.
Evaporation. Learning objectives At the end of this presentation the students will be able to: Explain the phenomenon of evaporation State the factors.
ENERGY CHANGES & STATES OF MATTER
Water in the Atmosphere Water vapor is the source of all condensation and precipitation. When it comes to understanding atmospheric processes, water.
EvaporationEvaporationEvaporationEvaporation F. 3A Winnie Chan (6) Lydia Chan (7) Vikki Chan (8) Stephanie Cheung (9) Vivian Chiu (10)
Aseel Samaro Understanding evaporation. Have you ever thought about what happens to the water particles when a puddle is left in the sunshine, or.
Water in the Atmosphere
Water & Changes of State
1 MELTING AND BOILING SEC 3 PHYSICS. 2 Melting Let us recall; Melting is a change of state from solid to liquid. Melting occurs at a fixed temperature.
Changes in State Chapter 2 Section 2. Energy How does the ice go from being a solid back to being a liquid? Energy is the ability to do work Energy.
Water in the Atmosphere
Atmospheric Moisture. How does the moisture get in the atmosphere?? EVAPORATION – liquid to a gas TRANSPIRATION – process of water being taken in and.
Evaporation Condensation Boiling Freezing, Regelation.
After a rain,why does the water on the ground dry up?
Bell work Observe two glasses of water. One is filled with ice water, and one is filled with warm water. Why do water droplets form on the outside of the.
2 pt 3 pt 4 pt 5 pt 1 pt 2 pt 3 pt 4 pt 5 pt 1 pt 2 pt 3 pt 4 pt 5 pt 1 pt 2 pt 3 pt 4 pt 5 pt 1 pt 2 pt 3 pt 4 pt 5 pt 1 pt HUMIDITY LATENT HEAT WATER.
Change of Phase Chapter 23. Topics  Phases  Evaporation  Condensation  Evaporation & condensation rates  Boiling  Freezing  Energy & changes of.
PHYSICS – Simple kinetic molecular model of matter (2)
Melting and Solidification
States Three states of matter : solid, liquid and gas Melting : change from solid to liquid Next Slide Boiling : change from liquid to gas Solidifying.
Humidity and Condensation Water is unique because it is the only substance that commonly exists in all three states of matter. Depending upon temperature,
2.3 Heat capacity and specific heat capacity
© 2010 Pearson Education, Inc. Unit 2: Heat Change of Phase.
Conceptual Physics/AOHS Change of Phase 03a Evaporation, Boiling
Conceptual Physics Change of Phase 03a Evaporation, Boiling
Methods of Energy Transfer. Recall…. Temperature is a measure of the kinetic energy of a sample of matter. It is the average measure of the rate of vibration.
Chapter 23: Change of Phase Review and Study Guide.
Chapter 18 Evaporation, Condensation, and Precipitation.
Book 1 Section 3.1 Latent heat
The temperature of boiling water does not increase even though energy is supplied to it continually. Warm-up Agree. Disagree.
What’s the MATTER!?!.
Book 1 Section 3.2 Evaporation
Weather Part 3 Humidity.
By Moizul Hasan Assistant Professor
Bell work Observe two glasses of water. One is filled with ice water, and one is filled with warm water. Why do water droplets form on the outside of the.
States States 1 States Three states of matter : solid, liquid and gas
Evaporation & Condensation
Evaporation When a liquid evaporates, faster particles escape from its surface to form a gas. However, unless the gas is removed, some of the particles.
Chapter 23: Change of Phase
How matter changes forms
What should I study for my Science Quiz
Presentation transcript:

Warm-up Wet floor is left to dry up. Are these examples of evaporation? Feeling cool under air-conditioner. Ironing wet clothes to dry them.

Warm-up Put it inside a room with all windows closed. Do you think the leaves of a plant get dry quickly in these cases? It is muggy and is going to rain. Strong sunlight shines on it. The plant is under a sea breeze.

Warm-up A bit warmer than it would be. How does the formation of snow or rain affect the temperature of the air? A bit cooler than it would be. No change. Others: _________

Liquid can change to vapour at temperatures below the boiling point. A liquid changing into a vapour is said to be evaporating. The process is called evaporation. Introduction

Differences between evaporation and boiling Evaporation and boiling require latent heat of vaporization.

1Cooling effect of evaporation Apply perfume/alcohol to your body... What do you feel? Perfume/alcohol evaporates easily and takes the energy from your body.

Sweat comes out of the pores, evaporates thus taking energy away from the skin. So we feel cool! 1Cooling effect of evaporation

No cooling effect occurs. So, we feel hot. On a humid day, the air is full of water vapour. This slows down the evaporation of sweat. Sweat tends to stay on the skin. 1Cooling effect of evaporation

You can easily catch a cold if you are wet. If it is windy, you cool down even more. As you dry out, latent heat is taken from your body. 1Cooling effect of evaporation

Evaporation is the escape of fast- moving particles from the surface of a liquid. Thus, some have higher K.E.! 2Evaporation and particle motion Different particles have different velocity.

Simulation

 average KE of the remaining molecules decreases  temperature of liquid   cooling effect slow molecules left behind fast molecules (high KE) near the surface may escape 2Evaporation and particle motion E

1Fast-moving particles in liquid escape and become vapour; Points to consider: 3Factors affecting evaporation

3The rate of evaporation (drying up) is a balance between the rate of escape and the rate of return. 2While slow-moving particles in vapour stick back to the liquid. 3Factors affecting evaporation

The rate of evaporation increases with the temperature of the liquid Molecules move faster on average. More molecules can escape. Molecules have more KE Temperature of water

larger the surface area, more molecules can escape at the same time. Greater is the rate of evaporation. When surface area is increased… Surface area of water

If the air is humid, it is full of water vapour. Water particles in vapour have greater chance to return to the liquid. more humid the air, the lower the rate of evaporation. evaporation Some return Humidity of air

If there is a breeze, the particles that escape from the surface of water get blown away. fewer particles in the vapour return to the liquid. a breeze increases the rate of evaporation. Movement of air

Condensation  the opposite of evaporation Warm air can hold more water. If warm humid air suddenly cools, some of the vapour has to condense.

This is how clouds and mist are formed from millions of tiny water droplets. Latent heat of vaporization is released when water vapour condenses. Condensation  the opposite of evaporation

AE = ml v applies to boiling but not to evaporation. BBoiling always occurs at a definite temperature but evaporation does not. CBoiling takes place at the surface, but evaporation occurs within the liquid. DBubbles are formed violently in boiling, but slowly in evaporation. Which is the difference between boiling and evaporation?

…because the oil layer __________ (slows/enhances) the evaporation of water (soup) longer slows Soup covered with oil takes ________ (longer/shorter) to cool down... Soup covered with oil…

True or false: When water vapour condenses, the surrounding air is warmed. (T/F) True or false: When...

___________________________________ ___________________________________ Increasing water temperature, Increasing surface area of water, Decreasing humidity, Increasing air movement Name any TWO factors that increase the rate of evaporation.

A person (mass 60 kg) doing exercise is covered with sweat. (a)If 1 litre (1 kg) of sweat is evaporated in 1 hour... …how much energy is required to evaporate this amount of water? Example 6

Energy required to evaporate 1 kg of water = ml v = 2.26  10 6 = 2.26 MJ = 1  2.26  10 6 Example 6

(b)If this amount of energy were not removed from the body by sweating... …by how much would the body temperature of the person  ? The average specific heat capacity of the human body is 3500 J kg -1 o C -1 Example 6

Apply E = mc  T,  T = E /mc = 2.26  10 6 / (60  3500) If the energy were not removed from the body by sweating, the body temperature would increase by 10.8 °C. Example 6  T = 10.8 °C

The experimental set-up is used to find the specific latent heat of vaporization of water. the electronic balance measures the mass of water boiled away Example 7

Switch on the heater only when it is immersed in water; otherwise it may be damaged. (a)State a precaution in this experiment. Example 7

A lid should not be added although it can reduce heat loss. Steam will condense on the lid and drip back into the cup.  error in the mass of water boiled away. (b)A student suggests that a lid should be added to the polystyrene cup to reduce heat loss. Example 7 Comment on his suggestion.

The error may be caused by 1Steam condensing on the top part of the heater dripping back into the cup. 2Energy loss to the surroundings. (c)The result obtained in the experiment is larger than the standard value. Explain. Example 7

Some water in the polystyrene cup evaporates... …and thus the balance reading drops. (d)After the heater has been switched off for a period of time, the reading shown on the balance drops slightly. Why? Example 7