Chapter 17, Problem 12TE

(a)

To determine

Whether grape juice turns to wine involves a physical or a chemical change.

Answer to Problem 12TE

It is a chemical change.

Explanation of Solution

A chemical change involves the rearrangement of one or more substances into new substances and a physical change involves the change in one or more physical properties in the substance, no new substances are being formed.

So when grape juice turns to wine, it is a chemical change as it changes into new substance.

Conclusion:

Conversion of grape juice into wine is a chemical change.

(b)

To determine

Whether wood burns to ashes involve a physical or a chemical change.

Answer to Problem 12TE

It is a chemical change.

Explanation of Solution

A chemical change involves the rearrangement of one or more substances into new substances and a physical change involves the change in one or more physical properties in the substance, no new substances are being formed.

So when wood burns to ashes, it is a chemical change as it is burnt in the presence of carbon dioxide and residue is formed in the form of ashes.

Conclusion:

Burning of wood is a chemical change.

(c)

To determine

Whether water begins to boil involves a physical or a chemical change.

Answer to Problem 12TE

It is a physical change.

Explanation of Solution

A chemical change involves the rearrangement of one or more substances into new substances and a physical change involves the change in one or more physical properties in the substance, no new substances are being formed.

So when water begins to boil, it is a physical change as it involves the change of state, no new substances are being formed.

Conclusion:

Boiling of water is a physical change as in this change only state of water is changed.

(d)

To determine

Whether a broken leg mends itself involves a physical or a chemical change.

Answer to Problem 12TE

It is a chemical change.

Explanation of Solution

A chemical change involves the rearrangement of one or more substances into new substances and a physical change involves the change in one or more physical properties in the substance, no new substances are being formed.

So when a broken leg mends itself, it is a chemical change as the food intake gives the energy and required calcium for healing the bone.

Conclusion:

Mending of broken legs is a chemical change.

(e)

To determine

Whether grass grows involves a physical or a chemical change.

Answer to Problem 12TE

It is a chemical change.

Explanation of Solution

A chemical change involves the rearrangement of one or more substances into new substances and a physical change involves the change in one or more physical properties in the substance, no new substances are being formed.

So when grass grows, it is a chemical change as the sunlight and nutrients from the soil are required to transform it into grass.

Conclusion:

Growth of grass is a chemical change.

(f)

To determine

Whether an infant gains 10 pounds involves a physical or a chemical change.

Answer to Problem 12TE

It is a chemical change.

Explanation of Solution

A chemical change involves the rearrangement of one or more substances into new substances and a physical change involves the change in one or more physical properties in the substance, no new substances are being formed.

So when an infant gains 10 pounds, it is a chemical change as the food intake by the infant helps to grow body fat and tissues.

Conclusion:

Increase in weight of an infant is a chemical change.

(g)

To determine

Whether a rock is crushed to powder involves a physical or a chemical change.

Answer to Problem 12TE

It is a physical change.

Explanation of Solution

A chemical change involves the rearrangement of one or more substances into new substances and a physical change involves the change in one or more physical properties in the substance, no new substances are being formed.

So when a rock is crushed to powder, it is a physical change as the rock will have the same chemical identity, it is just divided into smaller particles.

Conclusion:

Converted a rock into its powdered form is a physical change.