Entry Task: Block 2 Sept 6-7 ENTRY TASK: Write down the question. What’s the difference between a physical and chemical change? You have 5 minutes to answer this!!
Agenda COLLECT signed syllabus slips- 10 points –Bring in Monday- you get ½ the points Notes on Physical and Chemical –Properties and Changes HW: Physical/Chemical properties and changes worksheet- Due Monday
Physical and Chemical Properties
I Can… Using an example, explain the difference between physical and chemical properties.
Physical Properties Physical properties- are characteristics used to DESCRIBE matter color texture odor boiling point melting point conduction density malleable phase- at room temperature luster solubility
Physical property- details. Color the absorb/reflection of light off matter Odor the ability to sense smell Conduction- the ability to move electrons through its’ structure Malleable does not shatter/crumble if hit with hammer it flattens out- at STP Luster the ability to reflect light off its surface. Phase at standard room temperature and pressure (STP)- is it a liquid, solid or gas
Physical property- details. Solubility the ability to dissolve in a liquid- usually water can be other liquids as well Density the amount of matter (mass) in relation to how much space it takes up (volume) Melting point (the temperature to change from solid to liquid) Boiling point (the temperature to change from liquid to gas)
Lets look into Physical Properties Simple ones Color-gold Is it conductive? Yes Malleable- Can you smash it with hammer and not shatter it? Yes odorNo TextureSmooth Phase at room temperature- solid, liquid, or gas solid Luster- is it shiny Yes
Lets look into Physical Properties Simple ones gold Conductive Malleable No odor Smooth solid Difficult ones Boiling point- temp which it goes from a liquid to gas Melting point- temp which it goes from solid to liquid Luster
Lets look into Physical Properties Melting point- temperature which it goes from solid to liquid How do we find out its melting point? When the gold starts to become a liquid- At that temperature, is the MELTING POINT 1947 °F or 1064 °C
Lets look into Physical Properties Boiling point- temperature which it goes from liquid to gas How do we find out its boiling point? When the gold starts to become a gas- At that temperature, is the BOILING POINT 5084 °F or 2907 °C
What are chemical properties? Chemical property Can only be determined only when there is a change in the chemical composition of the matter involved. Chemical properties describes the ability of a substance to react with another substance.
What is the chemical property for this liquid? It Can you tell how or what it will react to? No… its not reacting!!! You can’t know the chemical property UNTIL it actually reacts with another substance
What is the chemical property for this liquid? What is this clear liquid? It will react with metals. It is safe near fires. Here are some clues It is safe to put on your skin It reacts to sodium bicarbonate It is a bleaching agent It kills bacteria It is not safe to drink
Think you know what this liquid is?
Examples of chemical properties Digestion React to acids/bases Cooking/Burning Spoiling Rusting- corrosion Flammable
Provide 6 properties Clear- transparent Amber color Liquid at room temperature From what we can obviously get- More clues Toxic It boils around 100 °F Flammable Has a distinct odor Does not dissolve in water Chemical properties Reacts with some plastics
What is this substance?
Is it physical or Chemical property? Reacts with a baseC Highly flammableC LustrousP Boils at 86°FP Does not dissolve in water P React to lightC Reacts to oxygenC Green in colorP Not malleableP Neutralizes acidC Reacts to metalsC Melts at 32°FP YOU WILL SEE SOME OF THESE on the P of U
Physical and Chemical Properties
I Can… Using an example, explain the difference between physical and chemical changes.
Physical Change When matter goes through a change in it’s physical appearance, it is called a physical change. Examples- ripping, ice cube melting, cutting hair, evaporation.
The act of changing involves – ING!! Its happening now! Like A red wooden fence being painted blue Water boiling (change from liquid to gas) Water freezing (change from liquid to solid) Water melting (change from solid to liquid) Salt dissolving in water Notice that the matter involved is NOT changing into a different substance.
In a physical Change Ask yourself- can I get the substance back to its original form? Yes Example- Dissolving sugar into water There are two changes, can you name them? Sugar dissolving into the water Water having sugar in it. How do I get the water back? Boil and catch the vapor back to liquid water After boiling what remains in the bottom is sugar. Then it’s a physical change
Refresher Chemical properties can be determined ONLY if the substance undergoes a change becoming a different substance. You can’t know the chemical property UNTIL it actually reacts with another substance
Chemical Changes Anything that can change chemical make-up is a chemical change. Examples- rusting car, burning paper, reacts to acid. 4Fe (solid)+2 O 2 (gas) 4FeO (rust)
Chemical change - chemical reaction This “chemical reaction” involves rearranging all the atoms in the matter to create a new substance. Are we making something new? Iron reacted with oxygen to form iron oxide Hydrogen peroxide breaks down with light to create hydrogen gas and oxygen gas. Baking soda reacted with vinegar to form water and sodium acetate.
How do you know if it’s going through a chemical change? When observing a “change” at least 2 of these have to be present. Temperature change Presence of a gas (bubbles) Color change Odor change Precipitate- solid floaters
Is it Physical or is it Chemical Change Salt dissolving in waterP Ice meltingP Reacts to light to form oxygen and water C Iron reacts with oxygen to create rust C Formation of a cloudP Wood rottingC Acid reacts with metal to create Copper nitrate C Burning paperC Light stick glowingC Wax meltingP Painting a fenceP Cooking eggsC
HOMEWORK: Complete the Physical/Chemical properties and changes worksheet!