Unit 2, Physical and Chemical Changes Flashcards
What is a physical change?
A change that happens without changing the identity of a substance.
What are some examples of physical changes?
-changes in shape
-smashing a glass
-boiling water
-dissolving sugar
-tearing paper
-chopping wood
-letting a soda go flat
What is a chemical change?
A change that happens that changes the identity of a substance.
What is evidence of a chemical change?
-new color
-bubbles form
-precipitate formed
-temperature change(energy change)
-light is made(energy change)
-sound is given off(energy change)
What are some examples of a chemical change?
-rusting
-rotting
-explosion
-fire
-bubbles when something is dropped in acid
-activating ice pack
-a cut healing
What two physical properties do rubber and wood have in common?
- don’t conduct electricity
- not attracted to a magnet
solid - gas
sublimation
gas - solid
deposition
solid - liquid
melting
liquid - gas
boiling, evaporating
liquid - solid
freezing
gas - liquid
condensation
What is 100*C called
“boiling point” and “condensation point”
What is 0*C called
“freezing point” and “melting point”
If a block of ice is melted into a puddle of water, would that be a chemical or physical change?
Physical as changes in phase of matter are not changing the identity of the substance
When you eat a McDonalds 30 piece chicken McNugget meal combo for energy, would that be a physical or chemical change?
Chemical as the food is dissolved in your stomach acid and it is an irreversible change.
What is a mixture?
It is a substance made up of two or more pure substances not chemically bonded
Is sugar a mixture or compound?
compound as it is made up of 2 or more types of atoms bonded chemically
Is a fruit salad a mixture or compound?
mixture
If you dissolve sugar in water, how would you get the sugar back?
You could let the water sit and evaporate and the sugar will be left in the container
When water is boiled, are the bubbles formed made out of hydrogen gas, oxygen gas, both, or neither?
Neither, as boiling is a physical change so, it can’t separate the water molecules into just hydrogen and just oxygen
During the electrolysis lab, you separated the water molecules into hydrogen and oxygen gas, is this a chemical or physical change?
Chemical as it created bubbles, and it changed the identity of the substance, in this case from water to hydrogen and oxygen
How did we determine the ratio of gasses during the electrolysis lab?
Water’s chemical formula is H2O, so there is 2x more hydrogen than oxygen. The slope compares the air between the gases from the two wires. The slope was 2 black/red. Slope is equivalent to ratios so the ratio is 2:1.
