Describing Matter Plasma

Physical vs. Chemical Properties A physical property can be observed or measured without changing the identity of the matter. Examples: SIZE ColorShape Density State of Matter (is it solid, liquid, or gas)

Some of the less obvious physical properties are: Solubility – the ability to dissolve in another substance (this substance does not have to be water!)

Melting point – the temperature at which a substance melts. Boiling point – the temperature at which a substance boils.

Malleability- the ability to be compressed or molded into thin sheets or just into another shape. Gold leaf Play Dough

Luster- is it shiny, sparkly, or glossy? Does it reflect light?

Ductility- can it be stretched without breaking? Can you draw it into thin wires? If something is brittle, it just breaks when you stretch it. This is the opposite of ductility.

Density, solubility, boiling point, melting point, and freezing point are all CHARACTERISTIC PROPERTIES of a substance. This means no matter how much of the substance you have, the density is the same. The solubility is the same. The melting and freezing points are the same.

CHARACTERISTIC PROPERTIES: Example: The density of 1 ml of water is 1 g/cm 3 The density of 100,000 kg of water is still 1 g/cm 3 The melting point of water is 0˚ C It doesn’t matter if it’s one drop of water or a whole bathtub full!

CHARACTERISTIC PROPERTIES are used to identify unknown substances. Examples: You find a bottle of clear, odorless liquid in the science classroom. You think it’s probably water but are not sure. So you weigh and measure it to find that its density is 1.4 g/cm 3. Can the liquid really be water?

Chemical Properties Chemical properties describe a substance based on its ability to change into a new substance with different properties. Example: Wood can be burned to create new substances (ash and smoke) with different properties.

Combustibility or Flammability: The ability to catch fire or burn.

Reactivity- does the substance tend to chemically react with other substances?

Physical Changes affect the physical properties of a substance. Examples: Tearing up your paper Crushing a can Freezing water into ice Bending a paper clip Dissolving salt in water Cutting your hair

Chemical Changes affect the chemical properties of a substance. Examples: Your car rusts Burning wood Glow sticks Baking a cake Food spoils Sodium reacts with water – BOOM!

Not sure if it’s a chemical or physical change? Physical changes can often be reversed or undone. Chemical changes can never be undone without another chemical change. Chemical changes produce NEW substances with NEW properties.

Signs of chemical changes: color change fizzing, foaming, or bubbling temperature change production of light, sound, or odor. A precipitate forms

Physical or Chemical Change? Iron Rusts

Physical or Chemical Change? Sodium Hydroxide dissolves in Water

Physical or Chemical Change? A match ignites and burns

Physical or Chemical Change? Icicles form at the edge of a roof

Physical or Chemical Change? Milk goes sour

Physical or Chemical Change? A chocolate bar melts in the sun

Physical or Chemical Change? Acid on limestone produces carbon dioxide gas

Physical or Chemical Change? Baking soda and vinegar react

Physical or Chemical Change? A tea kettle begins to whistle

Physical or Chemical Change? Wood and leaves rot to form humus

Lab Safety

Mystery Powders Lab Ms. Rary keeps all her baking supplies in clear plastic containers. Her roommate borrowed her supplies. The roommate used up all of the supplies and replaced them, but she got the containers all mixed up and now Ms. Rary has no idea what is in each container. There are 5 samples that you will need to examine and test in order to sort.