Question

Calculate the molarity of each of the following solutions:
30g of `Co(NO_(3))_(2)6H_(2)O` in 4.3Lpf solution
`30 mL of 0.5 M H_(2)SO_(4)`diluted to 500 mL

Answer 1

Molarity of soluion`=("Mass of solute"//"Molar mass of solute")/("Volume of solution in litres")`
Mass ofsolute, `Co(NO_(3))_(2).6H_(2)O=30g`
Molar mass of solute, `Co(NO_(3))_(2)6H_(2)O=59+2xx14+6xx16+6xx18=291gmol^(-1)`
Volume of solution=4.3L
Molarity (M)`=((30g)//(291gmol^(-1)))/((4.3L))=0.024 M`
Volume of undiluted `H_(2)SO_(4) "solution" (V_(1))=30mL`
Molarity of undiluted `H_(2)SO_(4) "solution" (M_(1))=0.5M`
Volume of diluted `H_(2)SO_(4) "solution" (V_(2))=500mL`
Molarity of diluted `H_(2)SO_(4)(M_(2))` can be calculated as :
`M_(1)V_(2)=M_(2)V_(2)`
`M_(2)=(M_(1)V_(1))/V_(2)=((30mL)xx(0.5M))/((500mL))=0.03M`