QUANTIFICATION Heat and temperature can be measured and quantified through a series of equations. There are 3 thermometers, 3 temperature scales. We can convert from one thermometer to another via these equations.

Temperature Conversion Practice K= C+273 C= (F-32)x 5/9 C= K-273 F= (C x 9/5) + 32 250 Kelvin to Celsius 339 Kelvin to Celsius 17 Celsius to Kelvin 55 Celsius to Kelvin 89.5 Fahrenheit to Celsius 383 Kelvin to Fahrenheit

Phase Change Diagram Increasing Temperature Sublimation Vaporizing Melting Condensing Freezing Deposition

Heat can travel but Temperature does not. Temperature can change as heat is added or removed. But temperature is a man made scale. Heat is pure energy. It does work. It can cause masses to move. Heat can also be transferred. Recall that work is the transfer of energy. So heat can transfer from one place to another. Heat can travel from one place to another by 3 ways. Conduction Convection Radiation

Cup gets cooler while hand gets warmer Ice gets warmer while hand gets cooler

Conduction Heat can travel by CONDUCTION. One object can cause cooler objects to heat up. Heat ALWAYS and ONLY travels from HOT to COLD. So via conduction, a hotter object can transfer the energy to a cooler object. It happens by contact. One object touches another and the energy of the hotter causes the molecules of the cooler to begin to move faster, that is they have more energy and thus the temperature goes up. Consider a metal spoon in a pan of hot soup. The handle would eventually get hot even though only the bowl of the spoon is in the soup so the atoms of hotter collide with atoms of cooler and transfer their energy. Conduction is the way heat travels through solids.

Convection 2. The second way that Q travels from one place to another is via convection. Heat travels through fluids this way Let us define a fluid… A fluid is anything that flows. Liquids flow. But so do gases…air masses flow in currents, air flows. When liquids and gases are heated, gain more energy then they become less dense. The molecules move faster and farther apart. Same mass in larger volume. As a result of less density hot liquids and gases rise. Removing energy from liquids and gases cools substances. The atoms and molecules have less energy, move slower, cannot escape gravity easily or for as long and so they tend to fall together and sink. “Fall together” means the molecules and atoms get closer to one another. That is the sample becomes more dense. The mass is the same but the volume is smaller. Because the molecules are more dense and because of that it sinks. Colder gases or liquids sink.

Radiation Radiation is the way heat can travel through a vacuum, through empty space. Heat travels through nothing on something called an electromagnetic wave. This is how heat reaches us from the sun. We will study more about EMR as we study light later on down the line. Radiation, waves, shouldn’t be confused with harmful radiation, that is waves of energy produced when the nucleus of an atom falls apart and radioactivity is released. This is just heat moving through space in something called an electromagnetic wave. Matter can react to EMR in two ways. The heat waves can be absorbed. The energy is taken in , the molecules start to move faster and the temperature goes up. OR…. Matter can reflect the heat waves. That is the object does not absorb the energy but simply allows it to bounce back like throwing a ball against a wall.

Properties of Matter Physical properties are those that can be observed without changing the make-up or identity of the matter. Clay is malleable. Squeezing changes the shape of the clay but not what the clay is made up of.

What is a physical change A physical change occurs when the substance changes state but does not change its chemical composition. For example: water freezing into ice, cutting a piece of wood into smaller pieces, etc. The form or appearance has changed, but the properties of that substance are the same (i.e. it has the same melting point, boiling point, chemical composition, etc.)

Characteristics of physical changes Melting point Boiling point Vapor pressure Color State of matter Density Electrical conductivity Solubility Adsorption to a surface Hardness

Chemical Properties Chemical properties describe matter on its ability to change into a new kind of matter with different properties. Paper is flammable: it is capable of burning in the presence of oxygen.

What are chemical changes A chemical change occurs when a substance changes into something new. This occurs due to heating, chemical reaction, etc. You can tell a chemical change has occurred if the density, melting point or freezing point of the original substance changes. Many common signs of a chemical change can be seen (bubbles forming, mass changed, etc).

Characteristics of Chemical Changes Reaction with acids Reaction with bases (alkalis) Reaction with oxygen (combustion) Ability to act as oxidizing agent Ability to act as reducing agent Reaction with other elements Decomposition into simpler substances Corrosion

Chemical changes continued Can be either endothermic or exothermic. Endothermic Reactions: Endothermic reactions draw heat in from their surroundings. Endo" means "to draw into," Exothermic Reactions: Exothermic reactions give heat off to their surroundings. "Exo" means "to give off."