The water molecule (H2O) is composed of 2 atoms of hydrogen and one atom of oxygen. What is the mass of one mole of water?
A. 3 g
B. 18 g
C. 6 g
D. 6.02 x 1023 g
B. 18 g
correct
To determine the mass of one mole of water, you need to know the atomic masses of hydrogen (H) and oxygen (O) and calculate the molar mass.
The atomic mass of hydrogen is approximately 1 gram per mole (g/mol), and there are 2 atoms of hydrogen in one molecule of water. Therefore, the total mass contributed by hydrogen is 2 x 1 g/mol = 2 g/mol.
The atomic mass of oxygen is approximately 16 g/mol, and there is 1 atom of oxygen in one molecule of water. Therefore, the total mass contributed by oxygen is 1 x 16 g/mol = 16 g/mol.
To find the total molar mass of water, you add up the contributions from hydrogen and oxygen: 2 g/mol + 16 g/mol = 18 g/mol.
Therefore, the correct answer is B. 18 g