Q. 3.79 - An Introduction to General, Organic, and Biological Chemistry

Question

Identify each of the following as a physical or chemical change: $(3,2)$

a. A plant grows a new leaf.

b. Chocolate is melted for a dessert.

c. Wood is chopped for the fireplace.

d. Wood barns in a woodstove.

Step-by-Step Solution

Answer

(part a) A chemical property is the ability to grow a new leaf.  New plant cells are being formed by the plants.${\mathrm{CO}}_2$ and${\mathrm{H}}_2\mathrm{O}$.

(part b) The melting of chocolate is a physical property.

(part c) No new substances are formed during the wood cutting process hence it is a physical property. 

(part d) Wood burning is a chemical property. 

Step 1: Given information (Part a)

A plant grows a new leaf. 

Step 2: Explanation (Part a)

A chemical property is the ability to grow a new leaf. This process results in the formation of new plant cells. By taking in new substances, the plant creates new ones.${\mathrm{CO}}_2$ and ${\mathrm{H}}_2\mathrm{O}$. As a result, it is a chemical property.

Step 3: Given information (Part b)

Chocolate is melted for a dessert. 

Step 4:Explanation (Part b)

Chocolate melting is a physical property. It melts when heated and solidifies again when cooled.

Step 5: Given information (Part c)

Wood is chopped for the fireplace. 

Step 6: Explanation (Part c)

Because no new substances are formed during the process of wood cutting, it is a physical property.

Step 7: Given information (Part d)

 Wood barns in a woodstove .

Step 8: Explanation (Part d)

Wood burning is a chemical property. Wood reacts with oxygen to form new substances in this environment. We will never be able to recover the original substance.