Answer:
Answer : The correct answer for mass of KBr = 2.53 g
Given :
Molarity of KBr solution = 0.85 M
Volume of KBr solution = 25 mL
Converting volume from mL to L ( 1 L = 1000 mL )
Volume of solution = 25 mL * \frac{1 L }{1000mL}Volumeofsolution=25mL∗
1000mL
1L
Volume of solution = 0.025 L
Mass of KBr = ?
Mass of KBr can be calculated using following steps :
1) To find mole of Kbr :
Mole of KBr can be calculated using molarity .
Molarity : It is defined as mole of solute present in volume of solution in Liter .
It uses unit as M or \frac{mol}{L}
L
mol
It can be expressed as :
Molarity = \frac{mol of solute (mol)}{volume of solution (L)}Molarity=
volumeofsolution(L)
molofsolute(mol)
Plugging value of molarity and volume
0.85 \frac{mol}{L} = \frac{mol of Kbr}{0.025 L}0.85
L
mol
=
0.025L
molofKbr
Multiplying both side by 0.025 L
0.85 \frac{mol}{L} * 0.025 L = \frac{mole of KBr}{0.025 L} * 0.025 L0.85
L
mol
∗0.025L=
0.025L
moleofKBr
∗0.025L
Mole of KBr = 0.02125
2) To find mass of Kbr :
Mass of Kbr can be calculated using mole . Mole can be expressed as :
Mole (mol) = \frac{mass (g) }{molar mass \frac{g}{mol} }Mole(mol)=
molarmass
mol
g
mass(g)
Mole of Kbr = 0.02125 mol
Molar mass of KBr = 119.00 \frac{g}{mol}
mol
g
Plugging values in mole formula
0.02125 mol = \frac{mass (g)}{119.00 \frac{g}{mol}}0.02125mol=
119.00
mol
g
mass(g)
Multiplying both side by 119.00 \frac{g}{mol}
mol
g
0.02125 mol * 119.00 \frac{g}{mol} = \frac{mass (g)}{119.00 \frac{g}{mol}} * 119.00\frac{g}{mol}0.02125mol∗119.00
mol
g
=
119.00
mol
g
mass(g)
∗119.00
mol
g
Mass of KBr = 2.53 g
