Question

23.4 g of solid NaOH was dissolved in water and the
solution was made up to 1000 ml. The whole of
this will neutralized completely
(1) 100 ml of 1 M H2SO4
(2) 20 ml of 2.5 M H2SO4
(3) 20 ml of 1.5 M H2SO4
(4) 30 ml of 5 M H2SO4
Doad Office · Aak​

Answer 1

Given :

• mass of NaOH = 23.4g
• volume of NaOH solution = 1000ml

To find :

• volume and molarity of H2SO4 that will neutralize given NaOH solution

Reaction involved :

• 2NaOH + H2SO4 => Na2SO4 + 2H2O

Formula used :

• number of mole = mass ÷ molar maas
• molarity = number of mole of solute ÷ volume of solution (in L)

Solution :

• moles of NaOH present = mass of NaOH ÷ molar mass of NaOH
• moles of NaOH = 23.4 ÷ 40
• moles of NaOH = 0.585 moles

according to reaction, for neutralizing 2 moles of NaOH we require 1 mole of H2SO4

therefore, for neutralizing 1 mole of NaOH , we need (1/2) mole of H2SO4

for , neutralizing 0.585 mole of NaOH , we will require => (1/2)×(0.585) mole of H2SO4

therefore mole of H2SO4 required = 0.2925

now we need to find number of moles of H2SO4 present in each given option

1) 100ml of 1M H2SO4

• molarity = number of mole ÷ volume of solution (in L)
• number of mole = molarity × volume of solution (in L)
• number of mole = 1 × (100/1000) = 0.1 mole

2) 20ml of 2.5M H2SO4

• number of mole = molarity × volume of solution (in L)
• number of mole = (2.5)×(20/1000)
• number of mole = 0.05 mole

3) 20 ml of 1.5 M H2SO4

• number of mole = molarity × volume of solution (in L)
• number of mole = (1.5)×(20/1000)
• number of mole = 0.03

4) 30ml of 5M H2SO4

• number of mole = molarity × volume of solution (in L)
• number of mole = 5×(30/1000)
• number of mole = 0.15 mole

• As no option matched there must be error in question!!

• There must be typing error, so I answered the same question asked in my book !!

QUESTION : 4 g of solid NaOH was dissolved in water and the

solution was made up to 1000 ml. The whole of

this will neutralized completely

(1) 100 ml of 1 M H2SO4

(2) 20 ml of 2.5 M H2SO4

(3) 20 ml of 1.5 M H2SO4

(4) 30 ml of 5 M H2SO4

Given :

• mass of NaOH = 4g
• volume of NaOH solution = 1000ml

To find :

• volume and molarity of H2SO4 that will neutralize given NaOH solution

Reaction involved :

• 2NaOH + H2SO4 => Na2SO4 + 2H2O

Formula used :

• number of mole = mass ÷ molar maas
• molarity = number of mole of solute ÷ volume of solution (in L)

Solution :

• moles of NaOH present = mass of NaOH ÷ molar mass of NaOH
• moles of NaOH = 4 ÷ 40
• moles of NaOH = 0.1 moles

• according to reaction, for neutralizing 2 moles of NaOH we require 1 mole of H2SO4

• therefore, for neutralizing 1 mole of NaOH , we need (1/2) mole of H2SO4

• for , neutralizing 0.1 mole of NaOH , we will require => (1/2)×(0.1) mole of H2SO4
• therefore mole of H2SO4 required = 0.05

now we need to find number of moles of H2SO4 present in each given option

1) 100ml of 1M H2SO4

• molarity = number of mole ÷ volume of solution (in L)
• number of mole = molarity × volume of solution (in L)
• number of mole = 1 × (100/1000) = 0.1 mole

2) 20ml of 2.5M H2SO4

• number of mole = molarity × volume of solution (in L)
• number of mole = (2.5)×(20/1000)
• number of mole = 0.05 mole

3) 20 ml of 1.5 M H2SO4

• number of mole = molarity × volume of solution (in L)
• number of mole = (1.5)×(20/1000)
• number of mole = 0.03

4) 30ml of 5M H2SO4

• number of mole = molarity × volume of solution (in L)
• number of mole = 5×(30/1000)
• number of mole = 0.15 mole

As number of moles of option 2) 20ml of 2.5M H2SO4 , contain 0.05mole of H2SO4 as required to neutralize NaOH solutions

so answer is option 2

ANSWER : option 2) 20ml of 2.5M H2SO4