Question

determine the mass of na2so4. 10 h2o required for preparing 250 ml of salt solution whose molerity is .45m

Answer 1

Given that  

Molarity = 0.45 M , mole / L

Volume = 250 ml ,  

 

We know that 1000 ml = 1.0 l

Therefore  

250 ml * 1.0 L/ 1000 ml

= 0.250 L

Molarity = number of moles / volume  

Number of moles = molarity * volume

= 0.45 * 0.250

= 0.1125 moles

Amount in g = number of mole * molar mass

=0.1125 moles  *322.1949 g/mol

= 36.25 g  

(Molar mass of Na2SO4*10H2O is 322.1949 g/mol.)