States of Matter
Name the three most common states of matter.
Solid, Liquid, Gas
True or false: Melting ice into water is a physical change.
True
What is a chemical change? Give one example.
New substance forms (example: burning wood → ash and gases)
What’s the difference between a mixture and a solution?
Mixture: components keep their properties.
Solution: one substance dissolves evenly in another.
The law of conservation of matter states that matter is neither _____ nor _____ in a chemical reaction.
Gained; lost
What state of matter has a definite shape and definite volume?
Solid
List two signs that a physical change has occurred.
Change in shape, change in temperature, change in state.
Name two signs that a chemical change might have occurred.
Release of heat or light, change in color, a new smell, gas bubbles, formation of a solid
Give an example of a mixture and an example of a solution.
Mixture: salad; Solution: salt water.
When water evaporates from a puddle, does the total mass of water decrease?
No; mass of water is conserved though it changes state to water vapor in the atmosphere.
Describe how particles behave in a gas compared to a solid.
Gas particles move freely and are far apart; solid particles vibrate in fixed positions and are close together.
Explain why cutting paper is a physical change, not a chemical change.
Paper molecules unchanged; only shape/size changed.
Explain why rust forming on iron is a chemical change.
Iron reacts with oxygen to form iron oxide; new substance with different properties.
How could you separate a mixture of sand and iron filings? Name the method and explain why it works.
Use a magnet to remove iron filings because iron is magnetic.
In a sealed container, vinegar and baking soda react and produce gas. If you measure mass before and after in the sealed container, what should you expect and why?
Mass stays the same because gas is contained; total mass conserved.
The temperature at which a liquid becomes a gas is called the _____________.
Boiling point
Describe what happens at the particle level when a liquid freezes into a solid.
Particles slow and pack into fixed positions forming a lattice.
What happens to the particles after a chemical change occurs?
They rearrange.
Explain how dissolving sugar in water forms a solution.
Sugar molecules spread out evenly throughout the water. You cannot see the sugar anymore.
Describe a simple investigation that would provide evidence for conservation of matter.
(Example) Measure mass of ice in a sealed plastic bag, let it melt, re-measure mass — mass should be the same.
Give an example of a substance that commonly exists as a liquid at room temperature and explain why it is a liquid.
(Example) Water is liquid; particles close enough to flow but not hold shape.
Identify two physical changes involved when making a smoothie from fruit and explain why each is physical.
Blending and mixing; no new substances formed.
Baking a cake involves chemical changes and physical changes. Name one chemical change that happens while baking and explain why it’s chemical.
(Example) Baking powder releases gases causing batter to rise; chemical reaction creates new gases.
Describe the two components of a solution and give an example of each.
Solute: substance that dissolves; salt.
Solvent: substance in which the solute dissolves; water.
A student observes a nail before and after it rusts. They claim that mass appears during a chemical reaction because the nail weighs more after it rusts. Explain why this is incorrect.
The student did not measure the mass of the oxygen in the atmosphere before the rust formed. The new mass is the combined total of the mass of the nail and the mass of the oxygen.