Question

A solution of F^- is prepared by dissolving 0.0889 plusminus 0.0004g of NaF(molecular weight= 41.989 plusminus 0.001g/mol) in 163.00 plusminus 0.06 mL of water. Calculate the concentration of F^- in solution and its absolute uncertainty

Answer 1

NaF------>Na⁺+F^-

Concentration of F^- ion in solution is,

0.0889⁺/_-0.0004g

------------------------     =   0.000545g/ml ⁺/_- 0.4867%

163.00⁺/_-0.06mL

Calculating absolute uncertainity,

Multiplication and Division: ADD the Relative Uncertainties.

Finding relative uncertainities = NaF = (0.0004/0.0889) x 100 = 0.4499%

Water = (0.06/163) x 100 = 0.0368%

adding relative uncertainities = 0.4499% + 0.0368% = 0.4867% = Absolute % uncertainity

Absolute uncertainity = (0.4867/100) x 0.000545g/ml = 0.00000265 g/mL