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2 years ago

10

Which of these involves the formation of a new chemical substance?

1 answer:

Len [333]2 years ago

4 0

Which of these involves the formation of a new chemical substance?

a. evaporation of gasoline

b. mixing salt and pepper

c. dissolving sugar in tea

d. rusting of an iron chain

$\\$

<h2><u>Answer:</u></h2>

D. Rusting of an iron chain

$__________$

<u>A. Evaporation of gasoline</u>

It does not form any chemical substance. Evaporation, is part of a physical change. Physical change only changes in its physical characteristics. Evaporation changes from liquid, to gas. Therefore, it is a physical change.

<u>B. Mixing salt and pepper</u>

No new substance formed. It does not form any chemical substance nor chemical change. When you mix salt and pepper, it only is a mixture wherein no new material can be form. Therefore, this is physical change as well.

<u>C. Dissolving sugar in tea</u>

When you dissolve sugar in your tea, it only changes the taste of the tea to sweet. Taste is part of the characteristic of physical change. It does not form any chemical substance nor chemical change. Therefore, this is physical change.

<u>D. Rusting of an iron chain</u>

Rusting is one of the common examples of chemical change in our daily lives. Rust is the new substance formed. However, this is considered as chemical change because this is irreversible or cannot be returned to its original substance/material. Finally, rusting of an iron chain involves the formation of new chemical substance.

<em><u>Hence, the answer is D. Rusting of an iron chain.</u></em>

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From the structure, you have:

I remember the following electronegativities most because they are fairly patterned:
EN
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=
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=
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EN
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Δ
EN
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−
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=
1.0
Δ
EN
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=
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Δ
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C
−
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=
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EN
C
−
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=
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Δ
EN
O
−
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4.0
−
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=
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C
−
F
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r
C
−
Cl
≈
177 pm
r
C
−
C
≈
154 pm
r
C
−
O
≈
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r
C
−
F
≈
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r
C
−
H
≈
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r
O
−
H
≈
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r
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r
C
≈
70 pm
r
H
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r
O
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F
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C
−
Cl
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C
−
H
bond (which is probably true).
The shortening of the
C
−
Cl
bond is somehow enough to be shorter than the
C
−
C
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