Question

Calculate the number of moles and amount in gram of NaOH in 250ml of a 0.100M NaOH solution. (Molar mass of Na = 23g/mol, H = 1g/mol, O = 16g/mol)​

Answer 1

Given:-

→ Volume of NaOH solution = 250mL

→ Molarity = 0.1 M

To find:-

→ Moles of NaOH.

→ Amount of NaOH in grams.

Solution:-

• Molar mass of Sodium (Na) = 23g/mol

• Molar mass of Hydrogen (H) = 1g/mol

• Molar mass of Oxygen (O) = 16g/mol

Hence, molar mass of NaOH :-

= 23 + 16 + 1

= 40g/mol

Now, let's convert the volume of solution from mL to L .

=> 1mL = 0.001L

=> 250mL = 250(0.001)

=> 0.25L

Let the required number of moles of NaOH be 'n' .

Molarity of a solution :-

= Moles of solute/Liters of solution

=> n/0.25 = 0.1

=> n = 0.25(0.1)

=> n = 0.025

Mass/ Amount of NaOH :-

= No of moles (n) × Molar mass

= 0.025×40

= 1g

Thus:-

• Number of moles of NaOH is 0.025.

• Amount of NaOH in grams is 1g .

Answer 2

NaOH-(23g=Na,=0=60g,H=1g)