Question

55 kernels of popcorn have a mass of 6.0 g before popping and 4.5 g after popping. How many water molecules are lost from an average kernel of popcorn?

Answer 1

The number of water molecules lost from an average kernel of popcorn when it pops is approximately 9.03 × 10²°. This is based on the mass loss per kernel and converting this into moles and then to the number of water molecules using the molar mass of water and Avogadro's number.

Step-by-step explanation:

When popcorn pops, it loses water, and consequently, its mass decreases. To calculate the number of water molecules lost from an average kernel of popcorn, we can follow these steps:

1. Determine the total mass loss of the popcorn when it pops. Subtract the mass of the popped popcorn (4.5 g) from the mass of the unpopped popcorn (6.0 g) to find the total mass loss.
2. Calculate the average mass loss per kernel by dividing the total mass loss by the number of kernels (55).
3. Knowing that the molar mass of water (H₂O) is approximately 18 g/mol and using Avogadro's number (6.022 × 10²³ molecules/mol), convert the average mass of water lost per kernel into moles and then into the number of water molecules.

Let's start with the calculation:

• Total mass loss = 6.0 g - 4.5 g = 1.5 g
• Average mass loss per kernel = 1.5 g / 55 kernels ≈ 0.027 g/kernel
• The number of moles of water lost per kernel = 0.027 g / 18 g/mol ≈ 1.5 × 10⁻³ mol/kernel
• The number of water molecules lost per kernel = 1.5 × 10⁻³ mol/kernel × 6.022 × 10²³ molecules/mol ≈ 9.03 × 10²⁰ molecules/kernel

Approximately 9.03 × 10²⁰ water molecules are lost from an average kernel of popcorn upon popping.