Question

One gram mole of a substance contains 6.022 x 10²³ molecules. 

1. 24 g of carbon is treated with 72 g of oxygen to form CO₂. Identify the limiting reagent. 

2. Find the number of molecules of CO₂ formed in this situation.

Answer 1

1. No. of moles of C = \(\frac{24}{2}\) = 12

No. of moles of O₂ = \(\frac{72}{32}\) = 2.25

2 mol of C requires 2 mol of O₂ . 

2 mol C completely reacts with 2 mol of O₂ and 0.25 mol O₂ and 0.25 mol O₂ remains unreacted. 

Hence, C is the limiting reagent. 

2. No. of moles of CO₂ formed = 2 

∴ No. of molecules of CO₂ formed

= 2 × 6.022 × 10²³ = 1.2044 × 10²⁴