States, Boiling Point, Melting Point, and Solubility

Solid Liquid Gas

Questions • What are the 3 states of matter?

• Write a definition for each state?

Defining States of Matter • States of matter are NOT defined by what they are made of.

– Example: solids can be elements (gold), compounds (Salt = NaCl), or mixtures (butter) Element (Au) Compound (NaCl) Mixture (Milk, Salt, etc)

Defining States of Matter • States of matter are defined by whether they hold SHAPE and VOLUME Element (Au) Compound (NaCl) Mixture (Milk, Salt, etc) ALL KEEP THE SAME SHAPE AND VOLUME = Solids

Defining States of Matter •

Solids

– have a definite SHAPE and VOLUME. Element (Au) Compound (NaCl) Mixture (Milk, Salt, etc) ALL KEEP THE SAME SHAPE AND VOLUME

Particle View of a Solid • Particles in a solid are PACKED CLOSELY together and they are in a FIXED POSITION.

Particles vibrate in place

Liquids •

Liquids

– has definite VOLUME but no defined SHAPE

100 ml

Particle View of a Liquid • Packed CLOSELY (like a solid), but move FREELY around each other (must stay in contact).

Gases •

Gases -

do NOT have definite SHAPE or VOLUME. Bromine gas fills up the entire volume of the container

Particle view of a Gas • Particles can MOVE FREELY and will either fill up or squeeze into available space.

Questions • 1) Which Statement is True?

– A) Liquids have a definite shape and volume – B) States of matter are defined by the substances they are made up of – C) Gases have a definite shape and volume – D) Solids have a definite shape and volume

Task • Draw a diagram of – A) Gas particles – B) Liquid particles – C) Solid particles

Changes in States of Matter •

Thermal Energy

– heat energy.

• More thermal energy = More particle movement

Changing States Increase Thermal Energy (Heat up)

Solid Liquid Gas

Decrease Thermal Energy (Cool off)

Melting point • •

Melting -

change from solid to liquid

Melting point -

melting occurs. SPECIFIC temperature when • Each pure substance has a SPECIFIC melting point.

– Examples: – M.P. of Water = 0°C (32°F) – M.P. of Nitrogen = -209.9 °C (-345.81998 °F) – M.P. of Silver = 961.93 °C (1763.474 °F) – M.P. of Carbon = 3500.0 °C (6332.0 °F)

Melting Point • Particles of a solid vibrate so fast that they break free from their fixed positions.

Increasing Thermal Energy

Solid Liquid

Melting point

Vaporization •

Vaporization

– change from liquid to gas • Vaporization happens when particles in a liquid gain enough energy to form a gas.

Increasing Thermal Energy

Liquid Gas

Boiling point

Two Kinds of Vaporization • •

Evaporation –

vaporization that takes place only on the surface of the liquid

Boiling –

when a liquid changes to a gas BELOW its surface as well as above.

Boiling Point •

Boiling Point

– temperature at which a liquid boils • Each pure substance has a SPECIFIC boiling point.

– Examples: – B.P. of Water = 100°C (212°F) – B.P. of Nitrogen = -195.79 °C (-320.42 °F) – B.P. of Silver = 2162 °C (3924 °F) – B.P. of Carbon = 4027 °C (7281 °F)

Boiling Point and Melting Point

WATER – H20

200 150 100 50 0 -50 -100 -150 Melting point Boiling point

time

Solubility • Maximum amount of a substance that can be dissolved in a liquid (at a specific temperature). Salt (NaCl) Water (H20) at 20 °C

Solubility • •

Solute

– substance being dissolved

Solvent

– liquid substance that solute is dissolved into Salt (NaCl) Water (H20) at 20 °C

Solubility • •

Solute

– ??????

Solvent

– ?????

Salt Water Salt (NaCl) Water (H20) at 20 °C

Solubility can change • •

Increased Temp = Increased Solubility Different substances have different solubility curves Solubility of Unknow n Substance at different tem peratures

3 2.5

2 1.5

1 0.5

0 1 3.8

6.6

9.4

12.2

15 17.8

tem perature (degrees Celcius)

20.6

23.4

26.2