chemistry chapter 2 section 4
Unlock all answers in this set
Unlock answersquestion
what is a chemical property?
answer
the ability of a substance to undergo a specific chemical change
question
one or more substances change into one or more new substances during _________?
answer
a chemical reaction
question
a substance that is present at the start of the creation is called the _______
answer
reactant
question
a substance that is produced during the reaction is called______
answer
product
question
what is a precipitate?
answer
a solid that forms when two liquids react
question
describe the law of conservation of matter
answer
mass is conserved in any physical change or chemical change...neither created nor destroyed
question
always true, sometimes true , never true: chemical properties are observed only when a substance undergoes a chemical change
answer
always true
question
describe what happens during a chemical reaction
answer
one or more substances change into one or more new substances
question
sometimes, always , rarely, never: a change in the composition of matter______occurs during a chemical reaction.
answer
always
question
Which representation of a chemical reaction is correct? a. products --------->reactants b.reactants--------->products
answer
B
question
list 4 possible clues to a chemical change
answer
1. transfer of energy 2. a change in color 3. the production of a gas 4. the formation of a precipitate
question
true or false: if you observe a clue for a chemical change, you can be certain that a chemical change has taken place.
answer
False
question
what is a precipitate
answer
a solid that forms and settles out of a liquid mixture
question
during a reaction , the mass of the products is always equal to the mass of the __________
answer
reactants
question
The law of conservation of matter states that in any physical change or chemical reaction, mass is neither ________ nor _________.
answer
created , destroyed
question
is burning paper a physical change or a chemical change?
answer
chemical change because the identity of the paper changes
question
what are the reactants in the above experiment
answer
paper and oxygen
question
what are the products in the above experiment?
answer
ash and gases
question
the ash produced when burning the paper has less mass that the original paper. was there a mass change that occurred? explain
answer
mass was conserved ash and gases were produced and those also have mass. The total of the paper and oxygen equals the total mass of the ash and gases.
question
How does a chemical cahnge affect the composition of matter?
answer
the composition of matter always changes during a chemical change
question
name 4 possible clues that a chemical change has taken place
answer
a transfer of energy, a change in color, the production fo a gas, the formation of a precipitate
question
in a chemical reaction, how does the mass of the reactants compare with the mass of the products?
answer
the mass of the products is always equal to the mass of the reactants
question
what is the main difference between physical changes and chemical changes?
answer
in physical changes, the chemical composition of a substance does not change; in a chemical cahnge, the chemical composition of the reactants changes as one or more products form
question
classify the following changes as physical or chemical a. water boils b. milk turns sour c. salt dissolves in water d. a metal rusts
answer
a. physical b. physical c. chemicals d,chemical
question
according to the law of conservation of mass, whne is mass conserved?
answer
mass is conservec in every physical change or chemical reaction
