Physical vs Chemical
physical change
mass divided by volume (D = m ÷ v)
This phase has definite shape and definite volume.
Solid
Particles that are tightly packed and vibrate in place represent this state of matter.
Solid
This property describes how much space an object takes up.
Volume
When a substance bubbles and produces gas during a reaction, this is evidence of this type of change.
Chemical change
An object has a mass of 30g and a volume of 10 cm³. What is its density?
3 g/cm³
The phase change from liquid to gas is called this.
evaporation (or vaporization)
If all particles in a diagram are identical and bonded together, this represents a _____.
Compound
Gold does not easily react with other substances. This means it is ______.
Inert
Name two signs that a chemical reaction has occurred.
Color change, gas production, temperature change, precipitate formation, or light production
If an object sinks in water, what can you conclude about its density?
It has a density greater than 1.0 g/cm³
Name one endothermic phase change.
melting, evaporation, or sublimation
A diagram showing two different types of particles evenly mixed but not bonded represents this.
Mixture
Give one physical property that can help identify a substance.
density, color, hardness, melting point
A student dissolves sugar in water. Is this a physical or chemical change? Explain why.
A physical change because no new substance is formed
Why is density considered a physical property?
It does not change regardless of the sample size?
When a gas turns directly into a solid, this process occurs.
deposition
Why are particle diagrams useful in chemistry?
They help us visualize how particles are arranged and interact
Why would mass alone not be enough to identify a substance?
mass depends on the amount of substance present
Iron rusting over time is what type of change and why?
A chemical change because a new substance (iron oxide) forms
Describe how you would find the volume of an irregular solid.
Using water displacement in a graduated cylinder
Explain what happens to energy during freezing.
energy is released (exothermic)
How can you tell the difference between an element and a compound in a particle diagram?
An element has only one type of atom, while a compound has two or more different atoms chemically bonded
You are given a crown and told it may be mixed with another metal. What property would best help you determine if it is pure without damaging it?
Density