Physical Chemistry> molarity...

what is the relationship between molarity and molality

himani raina , 14 Years ago

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15 Answers

RAGHVAN DAS

Last Activity: 14 Years ago

Molarity=(no of moles of solute)/(volume of solution in litrs)

while molality=(moles of solute)/(wt of solvent in kg)

the above two have a relationship as-

molality= Molarity/(density of solution-Molarity*molecular wt of solute)

m = M / (ρ - M x mw A)

apply this relation to solve numericals when density of solution is given...

Ritvik Gautam

Last Activity: 14 Years ago

Molarity is defined as number of moles divided by the volume (in liters).

whereas

Molality is defined as the number of moles divided by the mass of the solution (in kg).

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Jaya IITK

Last Activity: 14 Years ago

molarity = no. of moles ofsolute/vol of soln. in litre

molality = no. of moles of solute/ wt. of solvent.

if density of solvent is given we can find out relation between molality and morality..

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abhay prakash

Last Activity: 9 Years ago

Molality = molarity × 1000/consentrtion(g/l) – molarity × molar massUnite of LHS = mol /kgUnite of RHS = ( mol/liter)/(g/l – g/l) × 1000 = (mol/liter )/ (g/liter) × 1000) =mol/g × 1000 = mol/kgAccording to the unite of LHS and RHS this formula is right use this formula in numerical for qick and write answer

Rahul

Last Activity: 8 Years ago

Molarity(M)=m×d ______ 1+ m×M2 ________ 1000Where M2=molar mass of solute and d=density of the solution

anjaly

Last Activity: 8 Years ago

molarity is defined asno of moles of solute ÷volume of solution in litresmolality is defined as nomolesof solute ÷mass of the solvent in kilogramM(w÷1000+1÷M) = dwhere d is density

shubham

Last Activity: 8 Years ago

1÷molarity=1/density{1/molality+molecular weight of solution/1000} this is an easier way to find the relation between molality, molarity and density of solution

The iit guy

Last Activity: 8 Years ago

d=M(1/m+M2/1000)Where d is density of solution,M is molarity,m is molality,M2 is molecular mass of solute

kunal arora

Last Activity: 8 Years ago

Let M be the molarity Let m be the molality Let V be the volume of the solventLet X be the mass of solvent Let n be the moles of solute By formula, M = n/V ----(1)And By formula, m = n/X ----(2)Equating (1) & (2) for ` n ` - - > We get, MV = mX So molarity, M = mX/V And molality m = MV/X ---×----×-----×----P |_ € @ $ £ @ p p r ? \/ € The answer if you feel it helpful....Thank u

Rahul kurup

Last Activity: 7 Years ago

pls read full answer.
The relation between molarity and molality is as follows:-
1/M=1/d(1/m+K1/1000)
Here M=molarity
K1=molar mass of solute
m=molality
d=Density of solution
DERIVATION:-
Refer to above symbols and these symbols to understand derivation:-
n=moles of solute
V=volume of solution
WA=mass of solute
WB=mass of solvent
WS=mass of solution

Now m=n/WB
M=n/V and d=WS/V so V=WS/d.On substituting in M=n/V we get M=n/(WS/d)=(n*d)/WS
now m/M=(n/WB)/((n*d)/WS)
m/M=(n*WS)/(WB*n*d)
m/M=WS/(WB*d)
m/M=(WA+WB)/(WB*D).This is bcoz WS=WA+WB
m/M=(WA)/(WB*d)+(WB)/(WB*d)
m/M=(n*K1)/(WB*d*1000))+(1/d).This is bcoz n=given mass/molar mass.So n*molar mass=given mass.Therefore n*K1=WA.We divide K1 by 1000 to convert the molar mass(which is in grams) to kg.Now:-
m/M=(n/WB)*(K1/d*1000)+(1/d)
m/M=(m*K1/d*1000)+1/d.This is bcoz m=n/WB
m/M=1/d(((m*K1)/1000)+1)
1/M=1/d*m(((m*K1)/1000)+1)
1M=1/d((K1/1000)+1/m) .
Hence we derive the relation between molarity and molality.
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Anuj

Last Activity: 7 Years ago

Molality means 1 mol solute in 1 kg solvent Or 1000g solvent [ | m=mass÷ molar mass ~ mass = mMb ] | Or 1000g + m×Mb g solution. |

= 1000 + m×Mb ÷ density . |

M(molarity) = (mol of solute × 1000) ÷ volume in ml

M = 1000 × density × m ÷ (1000+mMb)

Prachi

Last Activity: 7 Years ago

d=M[1/m+molecular weight /1000]

Where,

d=density

M=molarity

m=molality

Here,

The formula of m=Wb/Mb×Wa(in kg

)

M=Wb/Mb×V(in litre)

And d=density=m/V

Where m=mass of given object

V=volume

ABHISHEK ANAND

Last Activity: 6 Years ago

let us take 1000ml of solution with density=P g cm^-1(rho) and molarity be M

mass of solution=1000P

let the molar mass of solute be M₂

mass of solute=M*M₂

mass of solvent=1000P-MM₂

MOLALITY=(M/1000P-MM₂)*1000=1000M/1000P-MM₂

MOLALITY(m)=M/(P-MM₂/1000)

1/m=(P-MM₂/1000)/M

1/m=P/M-M₂/1000

P/M=1/m+M₂/1000

Somanorani Ningthoujam

Last Activity: 6 Years ago

Molality(m) = Molarity(M) / 1000 d - M.Mb, where d is density of solution in gram per mole and Mb is molar mass of solute

Rishi Sharma

Last Activity: 5 Years ago

Hello students,
The solution of the above problem is attached.
I hope the solution will solve all your doubts.
Thank You,
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