Question

How many grams of Cu(NO₃)₂ are required to prepare 20.00 mL of a 0.118 M Cu²⁺ solution? Please use the Periodic Table to calculate the molar mass using the significant figures in that specific table.

molecular weight	???? g/mol Cu(NO3)2
mass Cu(NO3)2 required	???? g

Answer 1

Answers :

Molecular weight of Cu (NO₃ )₂ = 187.5558 g./mol

mass of Cu( NO₃ )₂ required .... = 0.4426 g .

Explanation -

Since one mole of Cu(NO3)2 on ionization yields one mole of Cu²⁺ ions

hence one mole of Cu(NO3)2 is equivalent to one mole of Cu²⁺ ion.

& 0.118 mole of Cu (NO3 )2 is equivalent to 0.118 M Cu2+ ion.

Accordingly 0.118M Cu(NO₃ )₂ is equivalent to 0.118 M Cu²⁺ solution .

Now, mass of Cu(NO3)2 required to prepare 1000ml of 0.118M solution = (187.5558 x 0.118 ) gms.

-------------------------------------------20.0ml----------------------- = ( 187.5558 x 0.118 x20 ) /1000

................................................................................................= 0.4426 gms.

............................................................................................or, =4.426 x 10^-4 gms.

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