(1) Label each of the following as either a physical change or a chemical reacti

Question

(1)   Label each of the following as either a physical change or a chemical reaction:

       (a) An iron nail rusts; (b) An ice cube melts; (c) A puddle of water evaporates.

(2) Label each of the following as either an intensive property or an extensive property:

     (a) Mass;    (b) Volume;    (c) Density;    (d) Temperature.

(3) (a) Construct a model to represent a heterogeneous mixture of two different compounds.

     (b) Construct a model to represent a homogeneous mixture of two different compounds.

(4) How many significant figures are contained in each of the following numbers?

    (a) 0.00261;   (b) 24;   (c) 240;   (d) 2.40;   (e) 5.20 x 102.

Explanation / Answer

Q1.

(a) An iron nail rusts; it is getting rich of OXYGEN, so this is CHEMICAL change

(b) An ice cube melts; it is still water, so this is PHYSICAL change

(c) A puddle of water evaporates., this is still water so this is PHYSICAL change

Q3

model of heterogeneous mix = hetero means various = use oil + water, they will form 2 phases, therefore hetero

model of homogeneous mix = homo means one/same = use alcohol + water, they will mix to form 1 single mix

Q4

(a) 0.00261 = 3

(b) 24 = 2

(c) 240 = 2; that last zero can't be accoutned as "accurate"

(d) 2.40 = 3, this last zero acounts for "accuracy" since it states an extra decimal

(e) 5.20*10^2. = 3, sinceall of them will give accurate data

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