Science Notes 11.5

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In a physical change, matter changes in
size, shape, or state without also changing identity
change of state is an example of a
physical change (solid to liquid gas)
combining 2 substances to form a solution is an example of
a physical change (example baking soda and water)
a solutio can be physically separated from each other to give back
original substances
chemical changes occur when
atoms link together in new ways
the changes cause
new compounds with different properties from the original
a chemical reactionn is a
chemical change of original substances into one or more substances
a reactant is
one of the orginial substances before a chemical change
products are
the new substances produced by the chemical reaction
What are the signs of a chemical change
a color change, formation of a gas, formation of light and heat
example of color change
potato and iodine
example of formation of a gas
lemon juice and baking soda
example of formation of light
a match
What are some familar chemical changes
baking a cake, rust, tarnish
rust forms when
iron atoms in steel react with oxygen from the air
what is needed for rust to occur
moisture
silver sulfide forms when silver reacts with
sulfer in foods or the air
what can remove tarnishes
polish
explain the chemical change of baking a cake
heat turns baking soda into sodium carbonate, steam and carbon dioxide gas
which is easier to reverse - chemical or physical changes
physical changes (example: ice cube)
are chemical changes easy to reverse, why
chemical changes are difficult to reverse (burnt toast)