Respuesta :

Sarah06109

Answer:

[tex]\boxed {\boxed {\sf 0.0018 \ mol \ H_2 O }}[/tex]

Explanation:

First, we need to find the molecular mass of water (H₂O).

H₂O has:

  • 2 Hydrogen atoms (subscript of 2)
  • 1 Oxygen atom (implied subscript of 1)

Use the Periodic Table to find the mass of hydrogen and oxygen. Then, multiply by the number of atoms of the element.

  • Hydrogen: 1.0079 g/mol
  • Oxygen: 15.9994 g/mol

There are 2 hydrogen atoms, so multiply the mass by 2.

  • 2 Hydrogen: (1.0079 g/mol)(2)= 2.0158 g/mol

Now, find the mass of H₂O. Add the mass of 2 hydrogen atoms and 1 oxygen atom.

  • 2.0158 g/mol + 15.9994 g/mol = 18.0152 g/mol

Next, find the amount of moles using the molecular mass we just calculated. Set up a ratio.

[tex]0.032 \ g \ H_2 O* \frac{ 1 \ mol \ H_2 O}{18.0152 \ g \ H_2 O}[/tex]

Multiply. The grams of H₂O will cancel out.

[tex]0.032 * \frac{1 \ mol \ H_2 O}{18.0152 }[/tex]

[tex]\frac{0.032 *1 \ mol \ H_2 O}{18.0152 }[/tex]

[tex]0.00177627781 \ mol \ H_2 O[/tex]

The original measurement given had two significant figures (3,2). We must round to have 2 significant figures. All the zeroes before the 1 are not significant. So, round to the ten thousandth.

The 7 in the hundred thousandth place tells us to round up.

[tex]0.0018 \ mol \ H_2 O[/tex]

There are about 0.0018 moles in 0.032 grams.

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