Question 19 Baking soda, NaHCO3, is an example of a(n) compound heterogeneous mixture element homogeneous mixture
The Correct Answer and Explanation is:
Correct answer: compound
Explanation:
Baking soda, chemically known as sodium bicarbonate (NaHCO₃), is a compound, not a mixture or an element. To understand why, let’s break down the terms:
- Element:
An element is a pure substance consisting of only one type of atom. For example, oxygen (O₂), gold (Au), and hydrogen (H₂) are elements because they contain only one kind of atom. Baking soda is not an element because it contains more than one type of atom. - Compound:
A compound is a pure chemical substance composed of two or more different elements that are chemically bonded together in a fixed ratio. Sodium bicarbonate (NaHCO₃) consists of sodium (Na), hydrogen (H), carbon (C), and oxygen (O) atoms chemically bonded in a specific structure. The atoms are combined in a fixed ratio and chemically react to form baking soda. Because the elements are chemically bonded, the properties of baking soda differ from those of its individual elements. For example, sodium is a highly reactive metal, and carbon dioxide (CO₂) is a gas, but baking soda is a stable, white, crystalline solid with distinct properties. - Mixtures:
Mixtures contain two or more substances physically combined, not chemically bonded, and their composition can vary. Mixtures can be:- Homogeneous mixtures (solutions): uniform throughout, e.g., salt dissolved in water.
- Heterogeneous mixtures: not uniform throughout, e.g., salad or sand mixed with iron filings.
Baking soda is not a mixture because its chemical formula is fixed and it has consistent properties throughout, which is characteristic of a compound.
Summary:
- Baking soda is a compound because it consists of different elements chemically bonded in a fixed ratio.
- It is not an element since it contains more than one type of atom.
- It is not a mixture, whether homogeneous or heterogeneous, because it is a pure substance with uniform properties and a definite chemical composition.
