A healthy human adult is composed of Oxygen (61.4%), Carbon (22.9%), Hydrogen (10.0%), and Nitrogen (2.6%) by mass. Calculate the weight gain for a 75 text kg individual if all ^1H atoms were replaced by ^2H atoms.

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EEJ MAIN Chemistry QUESTION #7200

Question 1

A healthy human adult is composed of Oxygen (61.4%), Carbon (22.9%), Hydrogen (10.0%), and Nitrogen (2.6%) by mass. Calculate the weight gain for a $75 \text{ kg}$ individual if all $^1H$ atoms were replaced by $^2H$ atoms.

$37.5 \text{ kg}$
$7.5 \text{ kg}$✔️
$10 \text{ kg}$
$15 \text{ kg}$

Correct Answer Explanation

Total mass of hydrogen in a $75 \text{ kg}$ person = $10\%$ of $75 = 7.5 \text{ kg}$.
$^1H$ has a mass of approximately $1 \text{ u}$, while $^2H$ (Deuterium) has a mass of $2 \text{ u}$.
Replacing all $^1H$ with $^2H$ effectively doubles the mass of the hydrogen component.
Weight gain = New mass - Original mass = $15 \text{ kg} - 7.5 \text{ kg} = 7.5 \text{ kg}$.

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