lesson 2(physical change and chemical change) Flashcards
what is matter?
matter is anything that takes up space and has mass.
what are physical changes
Physical changes affect the
appearance or state of a substance but don’t change what the substance is.
examples of physical change
• Melting ice → Still water.
• Cutting paper → Still paper.
• Breaking a pencil.
characteristics of physical change
- no new substance is formed
- changes in size, shape, or state(solid, liquid or gas)
- often reversible
- energy changes are small(like heat to melt or freeze)
what are intensive properties?
do not depend on the amount of matter in a sample.
remain the same regardless of the size of the sample.
what are extensive properties?
depends on the amount of matter in a sample.
changes when the quantity of matter changes.
what are chemical changes?
chemical changes happen when a substance turns into something completely new.
examples of chemical changes
burning wood - creates ash and smoke
mixing vinegar and baking soda - produces carbon dioxide gas
baking a cake
characteristics of chemical change
- new substance are formed
- can produce gas, heat, light, or a solid(precipitate)
- usually irreversible
- large energy changes occur
what are phase changes?
physical processes where a substance transitions from one state of matter (solid, liquid, gas) to another, driven by temptation, pressure, or energy changes
whats is melting?
-solid to liquid
-occurs when a solid absorbs enough heat to overcome the forces holding its particles in a fixed structure.
what is freezing
-liquid to solid
-occurs when a liquid loses heat, causing its particles to slow down and form a fixed structure
what is boiling?
-liquid to gas
-happens when liquid is heated to its boiling point, and particles throughout the liquid gain enough energy to form gas
what is evaporation?
-liquid to gas
-slower surface-level transition where molecules with enough energy escape from the liquid phase into the gas phase, even below boiling point.
what is condensation?
-gas to liquid
-occurs when gas particles lose energy and transition into the liquid phase
what is sublimation?
-solid to gas
-direct transition from solid to gas without passing through the liquid phase.
what is decomposition?
-gas to solid
-direct transition from gas to solid without passing through the liquid phase.
