Question

Calculate the mass in grams of a single water molecule,Express your answer using four significant figures

Answer 1

The mass of a single water molecule is 2.9915×10^-23 grams, calculated by dividing the molar mass of water (18.015 g/mol) by Avogadro's number (6.022×10^23 molecules/mol), and is expressed using four significant figures.

Step-by-step explanation:

To calculate the mass in grams of a single water molecule, you first need to understand that the molar mass of water (H2O) is 18.015 g/mol. Since one mole of any substance contains Avogadro's number of molecules (approximately 6.022×1023 molecules/mol), you can find the mass of a single molecule by dividing the molar mass by Avogadro's number.

To find the mass of one molecule of water:
Take the molar mass of water, which is 18.015 g/mol.

Divide this by Avogadro's number (6.022×1023 molecules/mol).

The result is the mass of a single water molecule.

Calculation:
(18.015 g/mol) / (6.022×1023 molecules/mol) = 2.9915×10-23 g/molecule

Therefore, the mass of a single water molecule is 2.9915×10-23 grams, expressed with four significant figures.

Answer 2

Step 1 - Calculating and interpreting the molar mass of water

The molar mass of water can be obtained from the molar masses of its constituent elements: H and O. These, in turn, can be found at a periodic table: 1 g/mol for H and 16 g/mol for O.

Since water's molecular formula is H2O, its molar mass will be:

`M_(H2O)=2*1+16=18g/mol`

This means that, in 18g of water, there is one mole of water molecules. One mole, in turn, corresponds to 6.02*10^23 molecules.

Step 2 - Calculating the mass in grams of a single water molecule

Now that we know the mass of 6.02*10^23 water molecules, we can use it to calculate the mass of a single water molecule:

`\begin{gathered} 6.02*10^(23)\text{ H2O molecules weights ---- 18g} \\ 1\text{ H2O molecule would weight ------ - x} \\ \\ x=(18)/(6.02)*10^(-23)=2.9*10^(-23)g \end{gathered}`

The mass in grams of a single water molecule is therefore ~3*10(-23) grams.