220g of carbon dioxide contains ----- moles

1. Analyze the question

You are asked to calculate the number of moles in a given mass (220g) of carbon dioxide ($CO_2$). To solve this, we need the molar mass of the compound.

2. Explain the concept

The relationship between mass, molar mass, and the number of moles is given by the formula:

• Mass (m): The given weight of the substance (220g).
• Molar Mass (M): The sum of the atomic masses of all atoms in the molecule. • Atomic mass of Carbon (C) = 12 • Atomic mass of Oxygen (O) = 16

3. Show the solution

Step 1: Calculate the Molar Mass of $CO_2$

• $CO_2$ consists of 1 Carbon atom and 2 Oxygen atoms.
• Molar Mass = $(1 \times 12) + (2 \times 16)$
• Molar Mass = $12 + 32$
• Molar Mass = 44 g/mol

Step 2: Calculate the number of moles

• Using the formula: $n = \frac{m}{M}$
• $n = \frac{220}{44}$
• $n = 5$

4. Identify the answer

The calculation gives us 5 moles. Comparing this to the options provided: A. 5 B. 6 C. 3 D. 4

The correct option is A.

5. Exam Tip

When dealing with molar mass questions in JAMB, always remember the atomic masses of common elements like Carbon (12), Oxygen (16), Hydrogen (1), and Nitrogen (14). If you can quickly sum these up, you save precious time during the exam! Also, ensure your units are consistent (grams to grams) before dividing.