States of Matter
Name the state of matter that has a definite shape and definite volume.
Solid
What is a physical change? Give a short definition.
Change in shape/state without new substance
What is a chemical change? Give a short definition.
Change producing new substances
What is the difference between a mixture and a solution in one sentence?
Mixtures=made when two or more substances are placed together but each substance keeps its own properties and can often be separated by physical means.
Solution = parts evenly spread and not easily separated.
State the law of conservation of matter in one sentence
Mass of matter stays the same during physical or chemical change
Which state of matter fills the entire volume of its container and has neither definite shape nor definite volume?
Gas
Which of these is a physical change: tearing paper, burning wood, or rusting iron? (Choose one and explain why.)
Tearing paper (physical) because no new substance.
List two signs (evidence) that a chemical change has occurred.
Color change, gas produced, new solid (precipitate), heat/light, new smell;
Give an example of a mixture that can be separated by a magnet and explain why the magnet works.
Example: iron filings + sand, magnet pulls iron out
If a student mixes 3.6 g of substance A and 2.1 g of substance B and a chemical change occurs, what total mass should they measure afterward.
3.6 + 2.1 = 5.7 g
Give one example of a substance that can be a solid, liquid, and gas depending on temperature.
Water
When ice melts into water in a sealed container, what happens to the total mass? Explain using conservation of matter.
Mass stays the same
Explain why burning charcoal is a chemical change and name at least one new substance produced.
Burning charcoal → ashes + gases (new substances)
Name three ways to make a solid dissolve faster in water.
Stirring, heating, grinding to smaller pieces
A sealed bag contains a seed, water, and air. The seed grows into a small plant inside the sealed bag. Will the mass of the sealed bag change?
Mass stays same because plant used matter from water/air inside bag
Explain, in one sentence, how particle arrangement differs between a solid and a liquid.
Solids=particles close/ordered, Liquids = particles close but move past each other
Name two physical properties that can change when temperature changes.
Solubility, flexibility, shininess (examples)
Using the particle model, write a short explanation of how particles rearrange during a chemical reaction
Particles A+B + C+D → A+D + B+C rearrange
Explain how you could separate salt from saltwater. List the physical property you would use.
Evaporation/distillation using boiling point (physical property)
In a closed container, 50 g of substance A reacts with 30 g of substance B. After the reaction, what total mass should you measure? Explain briefly.
0 g — mass is conserved because total mass before and after a reaction in a closed system stays the same.
Describe how you would use a thermometer and observations to determine whether a sample of water is at its boiling point or melting point
500=Boiling ~100°C (water vapor bubbles throughout) vs. Melting ~0°C (solid → liquid at that temp)
Name one real-world product where materials must resist physical change. Then give two physical properties you would test for that product.
Example: Playground surface. Test for durability (wear resistance) and flexibility (resists cracking).
Give one everyday example of a chemical change and name two pieces of evidence you would look for to confirm it.
Example: Baking a cake; evidence: a new color/texture and gas bubbles (rise), or heat released and a new smell.
You mix sugar and salt so well you cannot see the crystals. How can you tell whether this mixture is a solution or just a well-mixed mixture? Describe one test.
Try filtering (if separates its mixture), or evaporate solvent—if solids remain, not a true solution.
A student boils a liquid in an open container and notices less mass remains afterward. Explain two possible scientific reasons for the mass loss and relate each reason to the conservation of matter.
Possible reasons: (a) gas escaped during boiling (mass left the system) — if open system mass appears to decrease though total matter conserved including gas; (b) experimental loss from splashing or evaporation — account for in closed system.