How many hydrogen atoms are ther in 18.00mg of water?
18.00 mg = 0.018 g.
mols = g/molar mass.
To find the number of hydrogen atoms in 18.00 mg of water, we need to follow these steps:
1. Convert the mass of water from milligrams to grams. Since there are 1000 mg in a gram, we divide 18.00 mg by 1000 to get 0.018 g.
2. Determine the molar mass of water. Water (H2O) consists of two hydrogen atoms (H) and one oxygen atom (O). The molar mass of hydrogen is approximately 1.008 g/mol, and the molar mass of oxygen is around 16.00 g/mol. Thus, the molar mass of water is 2(1.008 g/mol) + 16.00 g/mol = 18.016 g/mol.
3. Calculate the number of moles of water using the formula:
moles = mass (in grams) / molar mass.
In this case, the moles of water = 0.018 g / 18.016 g/mol ≈ 0.000998 mol.
4. Since there are two hydrogen atoms in each molecule of water, we multiply the number of moles of water by the Avogadro's constant, which is 6.022 x 10^23 atoms/mol, to get the number of hydrogen atoms.
Number of hydrogen atoms = 0.000998 mol x (2 x 6.022 x 10^23 atoms/mol) ≈ 1.205 x 10^21 hydrogen atoms.
Therefore, there are approximately 1.205 x 10^21 hydrogen atoms in 18.00 mg of water.