Question

Twenty-five gram of table salt (NaCl) is dissolved in enough water to make a solution. How many moles of NaCl are dissolved in water?

		21.4 mole
		4.27 × 10-1 mole
		42.7 mole
		2.14 × 10-1 mole

Answer 1

Step 1: Explanation

Mole: The mass of substance containing the same number of fundamental units as there are atoms in exactly 12 g of ¹²C

No. of Moles = Mass given / molar mass

Step 2: Extract the data

Given,

Mass = 25 g

Molar mass of NaCl = ( 23 g + 35.45 g ) = 58.45 g / mole

Step 3: Calculate the moles

we know

No. of Moles = Mass given / molar mass

on substituting the value

=> No. of moles = 25 g / 58.45 g / mole = 0.427 mole = 4.27  × 10^-1 mole

Hence, the moles of NaCl dissolved in water =  4.27  × 10^-1 mole -------> option (B)