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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








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