What is the approximate molecular weight of water in grams per mole?

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Multiple Choice

What is the approximate molecular weight of water in grams per mole?

Explanation:
Molar mass is found by adding the atomic weights of all atoms in a molecule. Water has two hydrogens and one oxygen. Hydrogen is about 1 g/mol and oxygen is about 16 g/mol, so two hydrogens contribute ~2 g/mol and oxygen contributes ~16 g/mol. Together that’s roughly 18 g/mol for water. The numbers 28 and 44 correspond to different molecules (for example, N2 is about 28 g/mol and CO2 is about 44 g/mol), and 1 is the mass of a single hydrogen atom, not a water molecule. So the value around 18 g/mol is the correct molar mass for water.

Molar mass is found by adding the atomic weights of all atoms in a molecule. Water has two hydrogens and one oxygen. Hydrogen is about 1 g/mol and oxygen is about 16 g/mol, so two hydrogens contribute ~2 g/mol and oxygen contributes ~16 g/mol. Together that’s roughly 18 g/mol for water. The numbers 28 and 44 correspond to different molecules (for example, N2 is about 28 g/mol and CO2 is about 44 g/mol), and 1 is the mass of a single hydrogen atom, not a water molecule. So the value around 18 g/mol is the correct molar mass for water.

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