Question

We add excess na2cro4 solution to 71.0 ml of a solution of silver nitrate (agno3) to form insoluble solid ag2cro4. when it has been dried and weighed, the mass of ag2cro4 is found to be 0.470 grams. what is the molarity of the agno3 solution? answer in units of m.

Answer 1

Hello!

The precipitation reaction is the following one:

Na₂CrO₄(aq) + 2AgNO₃(aq) → Ag₂CrO₄(s) + 2NaNO₃(aq)

To know the molarity of the AgNO₃ we'll use the following molar equivalence equation:


`moles AgNO_3=moles Ag_2CrO_4 * 2 \\ \\ cAgNO_3*vAgNO_3=( (g AgNO_3)/(MM AgNO_3) )*2 \\ \\ cAgNO_3=(( (g Ag_2CrO_4)/(MM Ag_2CrO_4) )*2 )/(v AgNO_3)=(( (0,470 g Ag_2CrO_4)/(331,73 g/mol Ag_2CrO_4) )*2 )/(0,071 L)=0,040 M`

So, the concentration of AgNO₃ is 0,040 M

Have a nice day!