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 different amounts of energy when the substance is in different states.  For example, particles in liquid water have more energy than particles in ice. But particles of steam have more energy than particles in liquid water. Read and understand To change a substance from one state to another, you must _______ or _________ energy. A _______ is the change of a substance from one physical form to another.

Melting: Solid to Liquid  One change of state that happens when you add energy to a substance is melting.  Melting is the change of state from a solid to a liquid.  This change of state is what happens when ice melts.  Adding energy to a solid increases the temperature of the solid. Read and Understand

List examples for each of the following. An example for melting could be a popsicle in the sun. MeltingBoilingFreezing

True or False A melting point is a chemical property. Gallium is a metal that would not be a good choice for making jewelry. Melting points are the same for all substances. Double click in the blank area and type your answer for each statement.

ENDOTHERMIC  For a solid to melt, particles must overcome some of their attractions to each other.  When a solid is at its melting point, any energy added to it is used to overcome the attractions that hold the particles in place.  Melting is an endothermic change because energy is gained by the substance as it changes state. Read and Understand

Exothermic  For a liquid to freeze, the attractions between the particles must overcome the motion of the particles.  Imagine that a liquid is at its freezing point. Removing energy will cause the particles to begin locking into place.  Freezing is an exothermic change because energy is removed from the substance as it changes state. Read and Understand

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 Endothermic Reaction  Exothermic Reaction antacid being dropped in water burning paper mixing water with potassium chloride using dynamite Grab and drag the statements below to the correct column.

What do you know?  Energy is neither _________________ or ____________.  ______________________ releases energy and gives off heat.  _________ is given off in an exothermic reaction.  ___________________ absorbs energy resulting in lowering of temperatures. created exothermic reaction endothermic reaction heatdestroyed Click on the words below and move to the proper blank space.

EVAPORATION  Evaporation is the change of a substance from a liquid to a gas.  Evaporation can occur at the surface of a liquid that is below its boiling point.  For example, when you sweat, your body is cooled through evaporation.  Evaporation also explains why water in a glass disappears after several days. Read and Understand

List 3 places that you have seen evaporation take place.

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What do you know?  When a liquid changes to a gas it is called ___________.  When liquid molecules are ___________ the molecules move very _______________.  How quickly water evaporates depends on how much heat is _____________. Fill in the blanks.

TRUE of FALSE When water evaporates it is gone. If you place salt in water, the salt will be left behind when the water evaporates. Water vapor is all around us in the air.

Boiling Point  Boiling is the change of a liquid to a vapor, or gas, throughout the liquid.  Boiling occurs when the pressure inside the bubbles, which is called vapor pressure, equals the outside pressure on the bubbles, or atmospheric pressure.  The temperature at which a liquid boils is called its boiling point which is 100°C.  No matter how much of a substance is present, neither the boiling point nor the melting point of a substance change. For example, 5 mL and 5 L of water both boil at 100°C. Read and Understand

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Fill in the Blanks  What is needed to change any form of matter ____________________.  How do you change a solid into a liquid? ____________  When solids change to a liquid it is called ____________.  When liquids change to a solid state they have _________.  Liquid in a gaseous state is called ____________.  _________________ is a clear gas that is impossible to see.  _______________ is the process by which a gas turns into a liquid. add heat change of temperature melting vapor condensation Water vapor solidified

Condensation  Condensation is the change of state from a gas to a liquid.  Condensation and evaporation are the reverse of each other.  The condensation point of a substance is the temperature at which the gas becomes a liquid.  The condensation point is the same temperature as the boiling point at a given pressure. Read and Understand

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Place each phrase under the correct column. 2. When a gas is heated the molecules will slow down. 1.If the temperature is cooled enough then the droplets will turn into ice crystals. 3. When a gas cools enough it changes to a liquid. this is called evaporation. 4. If the temperature stays warm then the droplets stay as a liquid TRUEFALSE

Sublimation  Sublimation is the change of state in which a solid changes directly into a gas.  Dry ice is much colder than ice made from water.  For a solid to change directly into a gas, the particles of the substance must move from being very tightly packed to being spread far apart.  So, the attractions between the particles must be completely overcome.

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Fill in the Blanks  ________ is the process of a gas changing to a liquid.  __________ is the process of a liquid changing to a solid.  Freezing point is the temperature at which a ________ becomes a ___________.  The process of going from a solid directly to a gas is called _____________. sublimationcondensationfreezingsolidliquid

Quick Quiz True or False Evaporation can occur at any temperature. Boiling occurs only at the surface of a liquid. Evaporation is simply a liquid changing to a gas.

Quick Quiz---continued  What are two changes of state that are endothermic? Do the particles of a substance move faster or slower as the substance is heated? When water evaporates, has a chemical change or a physical change occurred? Click in the blank area below each question and answer it.

Quick Quiz---True/False A change of state is the conversion of a substance from one physical form to another. The freezing point and melting point of a substance are not the same temperature. Sublimation changes a solid directly to a gas.