Question

How many moles are present in $34$ grams of \[Cu{{\left( OH \right)}_{2}}\] ?

Answer 1

Hint: We know that it is generally represented by symbol mol. It's generally described as a unit of measurement for amount of substance Sl where stand for International System of unit. It's defined on basis of Avogadro's number and the formula here we will use is;
\[Number\text{ }of\text{ }moles\text{ }=~\dfrac{Mass}{Molar\text{ }Mass}\]

Complete step-by-step answer:
A mole of substance can be defined as containing exactly \[6.02214076\times {{10}^{5}}\] particle which may be atom where $6.02214076\times 10{}^\text{2}{}^\text{3}$ is known as Avogadro's number. Now inorder to calculate number of mole in $34$ gram of \[Cu{{\left( OH \right)}_{2}}\]we first have to calculate molecular weight of \[Cu{{\left( OH \right)}_{2}}\].

The molecular weight of substance is defined as weight in atomic mass units of each atom in a given formula where atomic mass unit is described as $\dfrac{1}{3}$ mole. The molecular weight of material is required to tell us individually how many grams are there in one mole of that chemical substance.

Molecular weight of \[Cu{{\left( OH \right)}_{2}}\text{ }=\text{ }\!\!\{\!\!\text{ }63.55\text{ }+\text{ }\left[ 2\left( 16 \right) \right]\text{ }+\left[ 2\left( 1.01 \right) \right]\text{ }\!\!\}\!\!\text{ }=\text{ }97.57\text{ }\dfrac{g}{mol}\]

This defines that \[34g\,of\, \text{ }Cu{{\left( OH \right)}_{2}}\text{ } \text{ }=\text{ }1\text{ }mole\text{ }of\text{ }substance\]

Thus by formula, \[Number\text{ }of\text{ }moles\text{ }=~\dfrac{Mass}{Molar\text{ }Mass}\]
We have the value of mass and molar mass and by substituting and dividing them we get the total number of moles present in \[Cu{{\left( OH \right)}_{2}}\]
\[\Rightarrow \dfrac{34}{97.57}\]
$\Rightarrow 0.348$

Therefore, there are \[0.348moles\] in $34$ grams of \[Cu{{\left( OH \right)}_{2}}\]

Note: Note that few things about copper hydroxide are also called cupric hydroxide which pale blue precipitate produces when the sodium hydroxide is added into excess solution of copper salt. Copper hydroxide is crystalline and it is also an inert compound used for preparing salts of wide variety.