How many molecules of ascorbic acid (vitamin c, c6h8o6) are in a 500 mg tablet?

1) molar mass of the C6H8O6, you need to consult the atomic weight of the C, H and O atoms that are in the periodic table: C is 12; H is 1; O is 16
(12x6)+(1x8)+(16x6)= 176g/mol

176 g = 1 mol
0,5 g =  x mol                500mg= 0,5 grams

molar mass = mass÷ moles
176 = 0,5÷ x
x= 2,84 x 10⁻³ mol

2) To find the number of molecules present in those 2,84 x 10⁻³ mol we need to multiple the moles by the Avogadro's constant
No. of molecules = Avogadro's constant  x n° of moles
No. of molecules = 6.022 x 10²³ x 2,84 x 10⁻³
= 1.71 x 10²¹ molecules of vit C.