Skip to main content

molality definition and formula

Molality Formula 

Molality definition and formula

It is characterized as the quantity of moles of solute 
present in 1 kg of solvent & is denoted by m.When we are estimating the physical parameter of an answer, what would it be a good idea for us to do? For certain reason, the use of molality to be sure is the most regular decision. Be that as it may, when we need to know the solute fixation in a  circumstance where there's a changing in temperature, molality won't work. This is on the grounds that the arrangement's volume will change somewhat alongside the temperature, that changes ends up having a slight impact to give a mistake that should be precise. Another parameter's required, something that isn't influenced by the temperature.
Molality = moles of solute(moles)
                                     Mass of solvent(Kg)

Molality Formula Questions:

1) What is the molality of an answer if 5.0 moles of solute are dissolved in 1.0  kilograms of water?
Answer:         
                        Molality = moles of solute
                                           Mass of solvent
                         
                         Molality =( 5.0) moles of solute
                                            ( 1.0) Mass of solvent
                     
                         Molality = 5  molal

2) What is the molality of an answer if 80.0 grams of NaOH are dissolved in 1.00 liter of water? (The density of water  equivalent to
1.00 gm/L )

Answer: Water is very well known as universal solvent and the density is regularly given as 1.00 grams per liter. This makes for a simple change from liters to kilograms.

Right now 80 grams of NaOH should be changed over to moles (for moles of solute) and one liter of water should be changed over into kilograms (for kilograms of solvent) utilizing the density.

To begin with, locate the molar mass of NaOH.
Na(sodium)= 23 gm/mole
O (oxygen) = 16 gm/mole
H(hydrogen) = 1.01 gm/mole

NaOH = 23.00 + 16.00 + 1.01 = 40.01

Second, convert the grams of NaOH into moles, utilizing the molar mass.
 No. Of moles = weight of solute
                             Molecular mass
   
     No. Of moles = 80    
                               40.01                                   

= 2 moles of NaOH

Third, convert the liter of water into kilograms utilizing the density.

= 1.00 kilograms

At last, utilize the molality condition to unravel

   Molality =( 2.0) moles of solute
                      ( 1.0) Mass of solvent
                     
  Molality = 2  molal








Labels:

Comments

Post a Comment

Please do not enter any spam link in the comment box

Popular posts from this blog

LAWS OF CHEMICAL COMBINATIONS

  LAWS OF CHEMICAL COMBINATIONS The combination of elements to form compounds is governed by the following five basic laws. 1)  Law of Conservation of  Mass It states that matter can neither be created nor destroyed.This law was put forth by Antoine Lavoisier in 1789. He performed careful experimental studies for combustion reactions for reaching to the above conclusion. This law formed the basis for several later developments in. chemistry Infact, this was the result of exact measurement of masses of reactants and products, and carefully planned experiments performed by Lavoisier . 2)Law of  Definite Proportions This law was given by, a French chemist, Joseph Proust. He stated that a given compound always contains exactly the same proportion of elements by weight. Proust worked with two  samples of cupric carbonate— one of which was of natural origin and the other was synthetic one. He found that the composition of elements presen...
Post a Comment
Read more

PROPERTIES OF MATTER AND THEIR MEASUREMENT

PROPERTIES OF MATTER & THEIR MEASUREMENT   Properties of matter & their measurement are divided in Physical and chemical properties . Every substance has unique or characteristic  properties. These properties can be classified  into two categories — physical properties ,  such as colour, odour, melting point, boiling point, density, etc., and chemical properties , like composition, combustibility, ractivity with acids and bases, etc.  Physical properties can be measured or observed without changing the identity or the composition of the substance. The measurement or observation of chemical properties requires a chemical change to occur. Measurement of physical properties does not require occurance of a chemical change. The examples of chemical  properties are characteristic reactions of different  substances; these include acidity or basicity,  combustibility, etc. 1)   Mea...
Post a Comment
Read more