Question

calculate the molarity of MgCl2 in the following solution: 5.34 g of MgCl2 is dissolved and diluted to 214 mL of solution.

Answer 1

Ⲁⲛ⳽ⲱⲉⲅ:

`\quad\hookrightarrow\quad \sf {0.262M }`

Ⲋⲟⳑⳙⲧⳕⲟⲛ :

Molarity is used to measure the concentration of a solution , so it is also as molar concentration. It is denoted as M or Mol/L

We are given that :

• Weight of
  `\sf MgCl_(2)` = 5.34g
• Volume of solution = 214 ml , or 0.214 L

The molar mass of magnesium chloride (
`\sf MgCl_(2)` ) is 95.21 g / mol

We can calculate the molarity of the solution by dividing the number of moles of solute by volume of solvent in liter ,i.e:

`\quad\longrightarrow\quad \sf {M = (n)/(V) }` ‎ㅤ‎ㅤ‎ㅤ⸻( 1 )

Where,

• M = molarity
• n = number of moles
• V = Volume

We can calculate the number of moles by dividing the actual mass by its molar mass ,i.e:

`\quad\longrightarrow\quad \sf { n = (w)/(m)}`‎ㅤ‎ㅤ‎ㅤ‎⸻ ( 2 )

Where,

• n = number of moles
• m = molar mass
• w = actual mass

Therefore,

`\implies\quad \tt {n =(w)/(m) }`

`\implies\quad \tt { n =(5.35\: g)/(95.21\: g /mol)}`

`\implies\quad{\pmb{ \tt {n = 0.056 mol}} }`

Putting the values in equation ( 1 ):

`\implies\quad \tt {M=(n)/(V) }`

`\implies\quad \tt { M =(0.056\:mol)/(0.214\:L)}`

`\implies\quad\underline{\pmb{ \tt { M = 0.262 \:M }}}`