Question

calculate the number of moles of methanol in 5 litre of its 2m solution if the density of solution is 0.981 kg per litre( molar mass of methanol is 32 gram per mole)​

Answer 1

Answer:

9.21 mol

Explanation:

Given :

Molality = 2 m

Density = 0.981 kg per litre

Molar mass  = 32 g

First let's calculate Molarity :

We know :

m = M / ( d - MM ) M

Where M represent Molarity :

2 = M / ( ( 0.981 - 32 ) M )

M = 1.842 M

Now we know :

Numbers of mole = volume × Molarity

No. of moles = 5 ×  1.842 mol

= > 9.21 mol

Therefore , number of moles of methanol is 9.21 mol.

Answer 2

Answer:

Divide the mass in grams by the molecular weight in grams per mole.

Explanation:

Given,

m=2

V=5 dm3

ρ=0.981 kg/dm3=0.981g/ml

M=32 g/mol

Since m=ρ×1000−Mb×M1000M

Since 2=0.981×1000−32×M1000M

M=1.844 mol/dm3

Number of moles of methyl alcohol =M×V=1.842×5=9.22 moles

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