Physical or Chemical
Breaking a stick of chalk into smaller pieces causes this type of change.
physical change
A silver necklace develops a dark coating called tarnish. The coating shows that this has formed.
A new substance.
This is the name for water in its gas state.
water vapor
This property tells how much matter an object contains.
mass
A damp iron bicycle chain develops this reddish-orange substance.
rust
Baking muffin batter forms new substances. This is the type of change that happens.
Chemical
A piece of cheese develops a new smell and mold. These observations support this type of change.
Chemical Change
A puddle gets smaller as liquid water enters the air as a gas. This process has this name.
evaporation
This science rule says matter is not created or destroyed during a physical or chemical change.
conservation of mass
Bread dough changes into bread in an oven. This provides the energy that causes the change.
heat
A frozen juice pop becomes liquid on a warm day. This change of state has this name.
A cracker is crushed into crumbs. This fact explains why crushing is a physical change.
The crumbs are still the same substance.
A bathroom mirror becomes covered with tiny drops after a warm shower. This change forms the drops.
condensation
A sealed bottle and everything inside have a mass of 180 grams. Two substances react inside, and nothing leaks out. This is the total mass afterward.
180 grams
Two identical iron washers sit in air. One stays dry, and one stays damp. Predict which will rust faster and explain why.
the damp washer, because water helps rust form
A student bends a copper wire into a heart without adding or removing metal. These two properties stay the same.
Mass and Volume
Red coloring mixes into water. A student says the color change proves a chemical change. Explain why that conclusion is not supported.
mixing colors can change appearance without forming a new substance?
A wet towel dries on a clothesline. Explain where the water goes.
it evaporates and enters the air as water vapor?
A glass holds 90 grams of water. Later, it holds 72 grams after some water evaporates. This much water has entered the air.
18 grams
A student brushes rust off an iron fence. The remaining fence has less mass. Explain why.
brushing off rust removes matter from the fence
Chocolate melts in a pan while a nearby piece of paper burns. Identify the type of change for each material.
Physical for the Chocolate
Chemical for the Paper
One cup bubbles because water is boiling. Another bubbles because two substances react and produce a new gas. Identify which cup shows a chemical change and explain why.
the reacting cup, because a new substance forms?
A sealed bag contains liquid water. In sunlight, some water evaporates. Later, cooling forms drops inside the bag. Explain why the total mass stays the same.
all the water remains inside the sealed bag
A log burns, leaving ash that has less mass than the original log. To check conservation of mass, these materials must be counted along with the log and ash.
the oxygen used and all gases and other products formed
Iron wool rusts inside a sealed jar. The iron wool loses mass, but the whole jar’s mass stays the same. Explain how both can be true.
oxygen already inside the jar joins the iron, while all matter stays inside the jar