Physical or Chemical?
Ice melts into liquid water. What type of change occurred?
Physical change. The substance is still H₂O.
Which state of matter has a definite shape AND definite volume?
Solid.
Which state of matter has particles with the lowest kinetic energy?
Solid.
Which property can be used to help identify an unknown substance: mass or density?
Density.
What is the formula for density?
Density = Mass ÷ Volume
A banana begins to rot. What type of change occurred?
Chemical change; new substances form as the banana decomposes.
Which state has a definite volume but takes the shape of its container?
Liquid.
As a solid melts into a liquid, what happens to the kinetic energy of its particles?
Their kinetic energy increases.
Which is affected by gravity: mass or weight?
Weight.
An object has a mass of 120 g and volume of 40 cm³. What is its density?
3 g/cm³
120 ÷ 40 = 3 g/cm³
Two liquids are mixed and immediately begin producing bubbles. What does this most likely indicate?
A chemical change most likely occurred because the bubbles may indicate that a gas was produced. The study guide identifies gas production as evidence of chemical change.
Which state of matter has no definite shape and no definite volume?
Gas.
Why can liquid particles move past one another while solid particles cannot?
Liquid particles have more kinetic energy and can move/slide past one another, while solid particles have less kinetic energy and remain in fixed positions.
Which is more useful for identifying a substance: boiling point or volume?
Boiling point.
A block is 5 cm × 2 cm × 4 cm and has a mass of 80 g. What is its density?
First calculate volume:
5 × 2 × 4 = 40 cm³
80 ÷ 40 = 2 g/cm³
Sugar dissolves completely in water. How could you test whether this was a physical change?
Boil/evaporate the water. If the original sugar remains, that provides evidence that dissolving was a physical change.
A substance escapes an open container and spreads throughout the room. What state of matter is it?
Gas.
Rank solids, liquids, and gases from lowest to highest kinetic energy.
Solid → Liquid → Gas.
Name TWO size-independent properties that could be used to identify an unknown substance.
Any two: density, boiling point, thermal conductivity.
Two liquids have the same volume, but Liquid A has more mass. Which liquid has the greater density?
Liquid A, because with equal volumes, the liquid with greater mass has greater density.
A candle is burning while wax melts down its side. Is this a physical change, chemical change, or both? Explain.
Both. Melting wax is a physical change, while burning is a chemical change because new substances form. This directly reinforces the candle example from their study guide.
Compare a solid, liquid, and gas in terms of shape and volume.
Solid: definite shape and volume. Liquid: no definite shape, definite volume. Gas: no definite shape or volume.
An ice cube melts on a table. Compare the movement of the water molecules before and after melting.
The particles have more kinetic energy and move faster after melting. The molecules themselves are still water molecules.
A student says, “I can identify an unknown liquid using its mass.” Explain why this is not a reliable identification property.
Mass depends on the amount of substance present, so different-sized samples of the same substance can have different masses. Size-independent properties such as density are better for identification.
An astronaut brings a sample of water from Earth into space. Does the water’s density change simply because gravity is different? Explain.
No. Density depends on mass and volume. A change in gravity affects weight, not mass, so simply moving the water to space does not change its density according to the study guide.