19.5 g of CH2FCOOH is dissolved in 500 g | Class 12 Chemistry Chapter Solutions, Solutions NCERT Solutions

Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter Solutions. This page offers a step-by-step solution to the specific question from Exercise 2, Question 33: . With detailed answers and explanations for each chapter, students can strengthen their understanding and prepare confidently for exams. Ideal for CBSE and other board students, this resource will simplify your study experience.

Question 33:

19.5 g of CH2FCOOH is dissolved in 500 g of water. The depression in the freezing point of water observed is 1.0°C. Calculate the van't Hoff factor and dissociation constant of fluoroacetic acid.

Answer:

Molecular mass of CH2FCOOH

14 + 19 + 12 + 16 + 16 + 1 = 78 g/mol

Now, Moles of CH2FCOOH = 19.5 / 78

= 0.25

Taking the volume of the solution as 500 mL, we have the concentration:

C = (0.25 / 500) X 1000

Therefore Molality =  0.50m

So now putting the value in the formula :

ΔTf = Kf x m

=1.86 x 0.50 = 0.93K

Van’t hoff factor = observed freezing point depression / calculated freezing point depression

= 1 / 0.93 = 1.0753

 

Let α be the degree of dissociation of CH2FCOOH

Now total number of moles  = m(1-a) + ma +ma = m(1+a)

Or

i = α(1+α) / α = 1 +α  = 1.0753

Therefore α = 1.0753- 1

= 0.0753

Now the Value of Ka is given as:

K= [CH2FCOO-][H+/  CH2FCOOH

(Cα x Cα) / (C (1-α))

= Cα2 / (1-α)

Ka = 0.5 X (0.0753)2  (1-0.0753)

= 0.5 X 0.00567 / 0.09247

= 0.00307 (approx.)

= 3 X 10-3

 

 

 

 

 


Study Tips for Answering NCERT Questions:

NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:

  • Read the question carefully and focus on the core concept being asked.
  • Reference examples and data from the chapter when answering questions about Solutions.
  • Review previous year question papers to get an idea of how such questions may be framed in exams.
  • Practice answering questions within the time limit to improve your speed and accuracy.
  • Discuss your answers with your teachers or peers to get feedback and improve your understanding.

Latest Blog Posts

Stay updated with our latest educational content and study tips

Smart Questions to Ask in a Parent-Teacher Meeting | PTM Made Easy

Parent-Teacher Meetings (PTMs) are more than quick updates on marks — they’re a chance to build a real partnership between home and school. A good Parent-Teacher Meeting conversation helps parents see beyond grades. It opens up insights about a child’s strengths, struggles, emotions and even hidden talents. When parents participate actively, they don’t just track […]

Read More

The Secret to Smarter Learning — Building Strong Critical Thinking Skills

In today’s world of endless information , knowing how to think is more important than knowing what to think . From school projects to real – life decisions , critical thinking helps students question ideas , analyze facts and form logical conclusions . But what exactly does critical thinking mean ? Simply put , it’s […]

Read More

Study Smarter, Not Harder: Build Productive Habits That Stick

Every student dreams of better grades , stronger focus and more study time – but the real challenge isn’t starting, it’s staying consistent . Building productive study habits is not about studying all day , it’s about studying smart . In today’s fast – paced digital world, distractions are everywhere – from endless phone notifications […]

Read More

The Hidden Risks of Online Gaming for Children — Is your child safe while gaming online?

Online gaming has rapidly become one of the most popular pastimes among children. Whether it’s multiplayer mobile games , PC adventures or console challenges , kids are spending more time than ever in the virtual world . On the surface, gaming seems entertaining and even educational – improving hand- eye coordination , teamwork and problem […]

Read More

Comments

  • lafo
  • Nov 27, 2019

Why do we take, K(f) to be 1.86?


  • Subham
  • Jun 01, 2019

Value of c will be equals to molality


  • Prince bharti
  • May 28, 2019

Great job


  • Prince bharti
  • May 28, 2019

Great job


  • priya
  • May 24, 2019

What a explanation


  • Hets
  • May 10, 2019

How the value of C is calculated for Ka...???


  • Ishan
  • Mar 06, 2019

C can be calculated by c=n/v


  • Akash shaw
  • Dec 18, 2018

How the value of 'C' is calculated for Ka value.


  • kandiwali
  • Jun 27, 2017

Great hard work.


Add Comment

Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 2 , Question 33: 19.5 g of CH2FCOOH is dissolved in 500 g of water. The depression in the freezing point of water obs....