Question

How many moles of $C{{o}^{2+}}$ are present in $0.200\text{ }L$ of a $0.400\text{ }M$ solution of $Co{{I}_{2}}$ ?

Answer 1

Hint : In the International System of Units, the mole is the unit of measurement for the amount of substance. It is defined as $6.02214076\times 10{}^\text{2}{}^\text{3}$ particles, which could be atoms, molecules, ions, or electrons. The definition of the mole can be used to convert mass and particle number.

Complete Step By Step Answer:
In chemistry, a mole is a unit of measurement. A mole of a substance is the mass of that substance that contains the same number of fundamental units as there are atoms in exactly $12.000g~$ of $12C$ . The mole is the SI unit for measuring the quantity of a substance.
It is represented by the symbol mol. In other words, 1 mol of carbon- $12$ has a mass of $12$ grams and contains $6.02214076\times 10{}^\text{2}{}^\text{3}$ carbon atoms. A mole of a substance is known as a material mass containing the same number of basic units as atoms in exactly $12.000g~$ of $12C$ .
$\begin{aligned} & Concentration=\dfrac{number\text{ }of\text{ }moles\text{ }of~solute~}{\text{ }volume\text{ }of\text{ }solution.}. \\\ & c=\dfrac{\eta }{\upsilon } \\\ & \therefore \eta =c\times \upsilon \\\ & \eta =0.4\times 0.2=0.08 \\\ \end{aligned}$

Note :
The mole is widely used in chemistry to express quantities of reactants and products of chemical reactions. The chemical equation $2{{H}_{2}}+{{O}_{2}}\to 2{{H}_{2}}O$ , for example, can be interpreted to mean that for every 2 mol hydrogen ${{H}_{2}}$ and 1 mol dioxygen ${{O}_{2}}$ that react, 2 mol of water ${{H}_{2}}O$ form. The mole can also be used to count atoms, ions, electrons, or other entities.
The molarity of a solution is commonly used to express its concentration, which is defined as the amount of dissolved substance in mole(s) per unit volume of solution, with the unit typically used being moles per litre $\left( mol/l \right)$ , commonly abbreviated M.