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20 questions
What happens in a chemical change?
The atoms in the reactants rearrange themselves and bond together differently to form one or more new products with different characteristics than the reactants. When a new substance is formed.
When objects or substances undergo a change that does not change into a different substance.
What happens in a physical change?
The atoms in the reactants rearrange themselves and bond together differently to form one or more new products with different characteristics than the reactants. When a new substance is formed.
When objects or substances undergo a change that does not change into a different substance.
Which type of change can be undone?
Chemical
Physical
What happens to the weight of matter when it undergoes chemical changes?
It stays the same
It increases
It decreases
What happens to the weight of matter when it undergoes a physcial change?
It stays the same
It increases
It decreases
What happens to wood after being burned?
It may seem as though burning destroys matter, but the same amount, or mass, of matter still exists after burning wood as before.
The Law of Conservation of Mass states that matter cannot be created or destroyed, so the weight of the matter is the same. Also suppose you had been able to measure the oxygen used by the fire and the gases produced by the fire. What would you find? The total mass of matter after the fire would be the same as the total mass of matter before the fire.
When wood burns, it combines with oxygen and changes not only to ashes but also to carbon dioxide and watervapor. The gases float off into the air, leaving behind just the ashes.
All of the above.
You tear home your homework into little pieces. How much does the homework weigh after you tear it up?
A little less
A little more
The same
None of the above
If you mix 1 gram of salt with 50 grams of water, how many grams of matter will you have after the salt is completely dissolved?
49 grams
50 grams
51 grams
None of the above
Which are clues that a chemical change has taken place?
Change in temperature
The color changes
The odor or smell changes
Formation of a precipatate
You see bubbles form
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