Are the following examples of chemical or physical changes?
Column A
1.
A silver spoon tarnishing:
A silver spoon tarnishing
2.
Blowing a dandelion:
Blowing a dandelion
3.
Building a sand castle:
Building a sand castle
4.
Toasting bread:
Toasting bread
Column B
a.Chemical change
b.Physical change
Column A
1. a. Chemical change
2. b. Physical change
3. b. Physical change
4. a. Chemical change
Column A:
1. A silver spoon tarnishing: Chemical change
2. Blowing a dandelion: Physical change
3. Building a sandcastle: Physical change
4. Toasting bread: Chemical change
Column B:
a. Chemical change
b. Physical change
To determine whether each example represents a chemical or physical change, we need to understand the differences between the two.
A chemical change involves a transformation of substances into new substances with different chemical properties. During a chemical change, the bonds between atoms are broken and new bonds are formed. This results in a change in the chemical composition of the materials involved.
On the other hand, a physical change refers to a change in the physical properties of a substance without any alteration in its chemical composition. Physical changes do not involve the formation of new substances but only affect attributes such as shape, size, state of matter, or phase.
Now, let's analyze each example:
1. A silver spoon tarnishing: This is a chemical change as the silver on the spoon reacts with substances in the air, such as sulfur, to form silver sulfide. This chemical reaction alters the composition of the silver.
2. Blowing a dandelion: This is a physical change as it only affects the position and dispersal of the dandelion seeds. The properties of the dandelion itself remain the same.
3. Building a sandcastle: This is a physical change as it involves manipulating the shape and arrangement of the sand particles, but there is no change in the chemical composition of the sand itself.
4. Toasting bread: This is a chemical change as the heat causes a chemical reaction in the bread, known as the Maillard reaction. It leads to browning of the bread, changes in texture, and the development of new flavors.
Based on this analysis, the answers for each example would be:
1. A silver spoon tarnishing: a. Chemical change
2. Blowing a dandelion: b. Physical change
3. Building a sand castle: b. Physical change
4. Toasting bread: a. Chemical change