Question #195124

It takes 40.7 KJ of energy to vaporize 1 mole of water ( heat of vaporization). Calculate the total amount of energy needed to vaporize 25g of water at 100C

Expert's answer

**Solution:**

When 1 mol of water at 100°C is converted to 1 mol of water vapor at 100°C, 40.7 kJ of heat are absorbed from the surroundings.

Convert the amount of water (H_{2}O) to moles:

(25 g H_{2}O) × (1 mol H_{2}O / 18.0153 g H_{2}O) = 1.3877 mol H_{2}O

Now, use the molar heat of vaporization as a conversion factor to determine how much heat would be needed to boil 1.3877 moles of water at its boiling point:

(1.3877 mol H_{2}O) × (40.7 kJ / 1 mol H_{2}O) = **56.48 kJ**

**Answer: 56.48 kJ of energy needed.**

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