Physical Properties
Define matter
anything that has mass and takes up space
Name the three main states of matter
Solid, liquid, gas
Define a mixture
Blend of two or more substances.
What is a chemical reaction?
Substances change into new substances.
Define an open system and give an example
Open: matter can enter/leave (open cup — liquid can evaporate)
Is flammability a physical or chemical property?
Flammability is a chemical property
Describe the particles in a liquid
particles are close but move freely throughout
Give one example of a heterogeneous mixture and one of a homogeneous mixture.
heterogeneous: sand + water. homogeneous: sugar dissolved in water.
In reactions, do particles break apart, join, or both?
Both: particles break and join to form new ones.
Define a closed system and give an example
Closed: nothing enters or leaves (sealed jar).
List three physical properties that can be observed without changing a substance’s chemical identity.
color, length, volume, opacity
Explain why gases are easily compressed, using what you know about the spacing of particles in gases.
Lots of empty space between particles in gases.
Why is sand + water heterogeneous but sugar + water homogeneous?
Sand stays as grains; sugar dissolves into individual molecules.
The chemical equation shown is H2+O2→H2O. Name the reactants and product
Reactants: H2, O2
Product: H2O
How can an open system lose mass during evaporation?
Evaporation lets molecules leave as gas, so mass decreases.
How would you measure volume in class?
use a graduated cylinder or ruler
What happens to particle motion when temperature goes up?
Motion increases; can cause melting or evaporation.
Explain why a helium balloon rises in air
Helium is less dense than air, so it rises.
List three examples of chemical reactions
rusting, combustion, digestion, photosynthesis, baking.
How does heat affect particle motion and states?
Heat makes particles move faster and can cause melting or evaporation.
Density=mass/volume. If a block has mass 150g and volume 50 cm3, calculate its density and explain if it will sink or float in water (assume water density is 1.0 g/cm3).
Density = 150g / 50cm3 = 3.0 g/cm3.
Since 3.0 g/cm3 > 1.0 g/cm3, the block is denser than water and would sink.
Explain at the particle level what happens when ice melts and then evaporates.
Melting: particles move faster, spread slightly, attractions weaken.
Evaporation: particles move much faster, separate into gas.
A sample of oil (mass 40 g, volume 50 cm3) is placed on top of water. Find the oil’s density and explain whether it will float or sink in water (water density 1.0 g/cm3).
50 / 40=0.8 g/cm3 → floats on water.
Why does iron rust when exposed to air and water?
Iron reacts with oxygen and water to form iron oxide (rust) — a new substance.
Give one lab example where treating the system as closed helps you measure mass.
Sealed container for reactions — prevents loss of mass when measuring