Question

Calculate the number of millimoles contained in 500mg of FeSO4•C2H4(NH3)2SO4.4H20 Calculate the number of grams of BaCrO4 that would have to be dissolved and diluted to 100ml to prepare a 0.200M solution.

Answer 1

`Millimoles\ of\ FeSO_4.C_2H_4(NH_3)_2SO_4.4H_2O= 1.3084\ millimoles`

The mass of
`BaCrO_4` required = 5.0674 g

Step-by-step explanation:

The formula for the calculation of moles is shown below:

`moles = (Mass\ taken)/(Molar\ mass)`

Given :

Mass = 500 mg

Molar mass of
`FeSO_4.C_2H_4(NH_3)_2SO_4.4H_2O` = 382.1455 g/mol

Thus,

`Millimoles= (500\ mg)/(382.1455\ g/mol)`

`Millimoles= 1.3084\ millimoles`

Also,

Molar mass of
`BaCrO_4`= 253.37 g/mol

Let the mass of the salt to prepare 100 mL 0.200 M solution = x g

The formula for the calculation of moles is shown below:

`moles = (Mass\ taken)/(Molar\ mass)`

Thus,

`Moles= (x\ g)/(253.37\ g/mol)`

`Moles= (x)/(253.37)\ mol`

Given that volume = 100 mL

Also,

`1\ mL=10^(-3)\ L`

So, Volume = 100 / 1000 L = 0.1 L

Molarity = 0.200 M

Considering:

`Molarity=(Moles\ of\ solute)/(Volume\ of\ the\ solution)`

`0.200=\frac{x}{253.37* {0.1}}`

x = 5.0674 g

The mass of
`BaCrO_4` required = 5.0674 g