Chapter 3 States of Matter

1. Chapter 3 States of Matter

2. Solids, Liquids and Gases 3.1

3. States of Matter Imagine that you have a baseball and a small packet of ketchup. 1. If you squeeze the ketchup packet, how would it change? The shape of the packet would change. 2. If you squeeze the baseball, how would it change? The baseball would not change shape in any noticeable way. 3. What would these results tell you about the properties of solids and liquids? You may say that solids have a shape that doesn’t change under ordinary circumstances but that a liquid can change shape (flow) as the shape of its container changes.

4. Describing Matter • Materials can be classified as solids, liquids or gases based on whether their shapes and volumes are definite or variable. • Shape and volume are clues to how particles within something are arranged

5. Solids • What do a pencil, quarter, book or cafeteria tray have in common? • A recognizable shape and they take up a certain amount of space. • They are all in a solid state • Solid is the state of matter in which materials have definite shape and volume. • Definite means that the shape and volume won’t change (as you move it) but obviously a pencils changes shape if you sharpen it

6. Liquids • Demo • Appearances are deceiving • A liquids always has the same shape as its container and can be poured from one container to another • A Liquid is the state of matter in which a material has a definite volume but not a definite shape.

7. Gases • What are some different gasses that you know? • Air is a mixture of gases • Natural gas or butane • Gas is the state of matter in which a material has neither a definite shape nor volume. • A gas takes the shape and volume of its container.

8. Atoms • The ‘shape’ and ‘volume’ of the Helium in the balloon is the same as the balloon itself. • The Helium atoms in a balloon are not arranged in a regular pattern. • They are spaced randomly throughout the balloon.

9. Arrangement of atoms in solids, liquids and gases

10. Other states of matter • On earth, almost all matter is a solid, liquid or gas • Other places in the universe, matter exists in other states. • At extremely high temperatures, matter can exist as plasma. (Such as on the Sun) • Einstein also predicted a fifth state of matter that would exist at extremely low temperatures (-273C). • Groups of atoms would behave as a single particle • Scientists were able to replicate this temperature ad found there was a 5th state of matter called the Bose-Einstein condensate (BEC)

11. Kinetic theory • Why is copper normally a solid, mercury a liquid and helium a gas? • Because the particles inside are moving at different rates – with different amounts of kinetic energy • Kinetic Energy is the energy an object has due to its motion • The fast an object moves the greater is kinetic energy. (What kind of proportion is this?) • The Kinetic theory of matter says that all particles of matter are in constant motion.

12. Behavior of Gases • The motion of particles in a gas are similar to the motion of balls in a game of pool. The ball moves in a straight line until it strikes another ball. Both balls change course. Kinetic energy is transferred during those collisions.

13. Motion in Gases • The particles in a gas are ever at rest. • Average speed of particles in a gas is 1600km/hr • Particles are not all moving at the same speed, some are slower and some faster • What can happen to the kinetic energy of 2 He atoms when the atoms collide? • one atom may gain kinetic energy and speed up while the other atom loses kinetic energy and slows down.

14. Behavior of Liquids • Do particles in liquids have kinetic energy? • Yes! So- why does mercury have a definite volume at room temperature instead of expanding to fill its container? • The average speed of a mercury (HG) atom is much slower than the average speed of a helium atom. • The particles in a liquid are more closely packed than the particles in a gas. • Think of going through the hallway before the bell rings and after the bell rings – which can you do faster? • A liquid takes the shape of its container because particles in a liquid can flow to new locations. • The volume of a liquid is constant because forces of attraction keep the particles close together. • Therefore, particles in a liquid cannot spread out and fill the container

15. Behavior of Solids • What is it like in a movie theater? • Each person remains in the same location- a ‘fixed’ location and the total volume does not change • This is what solids are like • Solids have a definitevolume and shape because particles in a solid vibrate around a fixed location. • Lab Oobleck

16. The Gas Laws • 3.2

17. 3.2 The Gas Laws • What happens when you shake up a soda? • It builds up pressure- but where does the pressure come from? • CO2 gas is released as you shake it up • Pressure is the result of a forcedistributed over an area. • when you shake up the soda bottle, pressure builds up and causes a force to be distributed over the area inside the bottle

18. Pressure • The SI Unit of pressure comes from the units for force and area. • Force is measured in newtons(N) • Area is measured in meters(m2) • When a force in newtons is divided by an area in m2, the unit of pressure is newtons per square meter (N/m2) • the pascal(Pa), is shorthand for N/m2 • A pascal is very small, so in science we often use kilopascals(kPa)

19. Pressure • Gaspressure is produced by particles colliding with the walls of a container (like a balloon) • When so many particles collide with the walls of the container simultaneously, they produce a measurablepressure. • Collisions between particles of a gas and the walls of the container cause pressure in a closed container.

20. What do you think happened here? A real example of where a ‘can’ gets crushed by air pressure! The tanker was carrying hydrocarbon fuel – why do you think it crushed after being emptied and then being transported up a mountain? What affects can effect Gas Pressure?

21. Factors that Affect Gas Pressure • What are the particles of a gas doing? • What factors could affect those particles? How else could gas pressure be affected? • Particles could move faster or slower • you could move the gas from a larger container to a smaller one • You could add or remove gas from the container • Factors that affect pressure in a closed container are: temperature, volume, and the numberofparticles.

22. Temperature • Raising the temperature of a gas will increase its pressure if the volume of the gas and number of particles are constant. • If the temperature goes up the average kineticenergy goes up and the particles movefaster. • The particles collide with the wall of the container moreoften and with more force, increasing the pressure.

23. Number of Particles • Increasing the # of particles will increase the pressure of a gas if the temperature and volume are constant. • What happens if you keep blowing air into a balloon?

24. Volume • Reducing the amount of volume of a gas increases its pressure if the temperature of the gas and number of particles are constant. • If I have the same amount of particles in a smaller container, will the pressure be increased?

25. Example • Volume and Pressure are factors when you breathe • As you inhale, the diaphragm contracts causing your chest cavity to expand. • This increases the volume and allows the particles in air to spreadout, lowering the pressure in your chest. • The pressure outside your body is now greater than inside and air rushes into your lungs. • How does the movement of your rib cage affect your chest cavity? • The volumeincreases as the rib cage is liftedup and out. The volumedecreases as the rib cage movesdown and in.

26. Gas Laws • There are several gas laws that describe the behavior of gas. • Boyle’s Law, Charles’s Law and the combined gas law. • We also have 4 variables that we use when describing gases: • Temperature (T) • Pressure (P) • Volume (V) • And the amount of gas which is expressed in number of moles (n)

27. Charles’s Law • Jacques Charles (the inventor of the hydrogen balloon) studied the behaviorof gases. • He discovered that when he graphed volume vs. temperature of gases that as the volumeof a gas increases, the temperatureof the gas also increases. • Charles’s law states that the volume of a gas is directlyproportional to its temp in K if the pressure and number of particles is constant. The mathematical expression is V1 = V2 T1 T2

28. Boyle’s Law • Robert Boyle described the relationship between pressure and volume. • If the volume of a cylinder is decreased, the pressure increases. • Boyle’s Law states that the volume of gas is inversely proportional to its pressure if the temperature and number of particles are constant. P1V1=P2V2

29. The Combined Gas Law • Boyle’s Law and Charles’s Law can be combined to form one law called The Combined Gas Law • This law describes the relationship between temperature, volume and pressure of a gas. • The combined gas law can be used to solve problems involving gases.

30. Section 3.2 The Combined Gas Law

31. Section 3.2 The Combined Gas Law

32. Section 3.2 The Combined Gas Law

33. Section 3.2 The Combined Gas Law

34. Math Practice • Pg 80 1, 2 and 3. • Don’t forget temperature conversions!