Astock solution of na3c16h9n4o9s2 (tartrazine, or yellow no. 5) was prepared by placing 0.035- g in a 500 ml volumetric flask and diluting to 500 ml with distilled water. what is the molar concentration?

First, determine the molar mass of tartrazine by adding up the product of the number of moles of the substance with the molar mass of each of the element. 

    molar mass of tartrazine = (3 mol Na)(23 g Na/1 mol Na) + (16 mol C)(12 g C/1 mol C) + (9 mol H)(1 g H/1 mol H) + (9 mol O)(16 g O/1 mol O) + (2 mol S)(32 g S/1 mol S) = 478 g/mol

Then, determine the number of moles of the substance by dividing the given mass by the calculated molar mass.

     n = (0.035 g)(1 mol tartrazine / 478 g tartrazine)
       = 7.32 x 10⁻⁵ mol of tartrazine

Then, divide the calculated number of moles by the volume of the solvent in L which will be equal to 0.5 L.

   M = (7.32 x 10⁻⁵ mol of tartrazine / 0.5 L) = 1.46 x 10⁻⁴ M tartrazine

ANSWER: 1.46 x 10⁻⁴ M tartrazine