Question

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The mole is a counting number that allows scientists to describe how individual molecules and atoms react. If one mole of atoms or molecules is equal to 6.022 × 10^23 atoms or molecules, how many molecules are in a 23.45 g sample of copper (II) hydroxide, Cu(OH)2? Express your answer to the correct number of significant figures. (MM of Cu(OH)2 is 97.562 g/mol)

Answer 1

Mass of Cu(OH)2 = 23.45 g

Molar mass of Cu(OH)2 = 97.562 g/mol

Since we know,

Moles = Mass/Molar mass

\Rightarrow Moles = (23.45 g)/(97.562 g/mol) = 0.2404 moles

Since 1 mole of substance contains = 6.022 × 1023 molecules

So 0.2404 moles will contain = 0.2404*(6.022 × 1023 molecules) = 1.448 × 1023 molecules

Step-by-step explanation:

Answer 2

`\large \boxed{1.447 * 10^(23)\text{ molecules Cu(OH)}_(2 )}`

Step-by-step explanation:

1. Calculate the moles of copper(II) hydroxide

`\text{Moles of Cu(OH)}_(2) = \text{23.45 g Cu(OH)}_(2) * \frac{\text{1 mol Cu(OH)}_(2)}{\text{97.562 g Cu(OH)}_(2)} = \\\\\text{0.240 36 mol Cu(OH)}_(2)`

2. Calculate the molecules of copper(II) hydroxide

`\text{No. of molecules} = \text{0.240 36 mol Cu(OH)}_(2) * \frac{6.022 * 10^(23)\text{ molecules Cu(OH)}_(2)}{\text{1 mol Cu(OH)}_(2)}\\\\= 1.447 * 10^(23)\text{ molecules Cu(OH)}_(2)\\\text{The sample contains $\large \boxed{\mathbf{1.447 * 10^(23)}\textbf{ molecules Cu(OH)}_{\mathbf{2}}}$}`