Answer to Question #297896 in General Chemistry for sha

Question

Calculate the molarity and molality of an NH3 solution made up of 35.0 g of NH3 in 75.0 g of water. The density of the solution is 0.982 g/mL

Answer 1

Molarity

$Mass=35+75=110g$

Volume$=110×0.982=108.02ml$

Molar mass of NH$_3=17.031$

Number of moles $=\frac{35}{17.031}=2.055$ moles

Molarity $=$ Moles$/$ Litre

$=\frac{1000}{108.02}×2.055$

$=19.02M$

Molality $=$ Moles$/$ kg of solvent

$=2.055×\frac{1000}{75}$

$=27.4$ mole$/$ $kg$