Answer to Question #267918 in Organic Chemistry for Malek

Question

The reaction between the unknown Ni-salt and dimethylglyoxime can be expressed by the following chemical equation:

[NiA • 6H₂O] + H₂dmg + 2OH^–_(aq) = Ni[dmg]₂ ↓ + 8H₂O

where,

NiA • 6H₂O is unknown Ni-salt (which is hexahydrate and A is unknown anion)

H₂dmg is dimethylglyoxime

Ni[dmg]₂ is bis(dimethylglyoximato)nickel complex which is insoluble in water

You successfully isolated and dried Ni[dmg]₂ and got the mass of 1.1899 g. 

What is the molecular mass of the unknown NiA • 6H₂O salt if you were given 1.3451 g of the salt?

 

Answer 1

Suppose the mass of sample is 100 g.

The mass of water is 21.8 g.

The mass of anhydrous salt N

i

C

l

2

NiCl2

 is 100

−

21.8

=

78.2

g

.

100−21.8=78.2g.

The formula to calculate moles is as follows:

M

o

l

e

s

=

M

a

s

s

M

o

l

a

r

m

a

s

s

Moles=MassMolarmass

The molar mass of water is 18.01 g/mol.

The molar mass of nickel chloride is 128.69 g/mol