Question

A) Calculate the molar mass of serotonin, a neurotransmitter. The molecular formula for serotonin is C₁₀H₁₂N₂O.

B) How many sodium ions are present in 18.9 g of Na₃PO₄?

Answer 1

Ans A:

Molar mass of the compound is the sum of individual masses of its constituent atoms.

C = 12.01 g/mol

H = 1.01 g/ mol

N = 14.01 g/mol

O = 16.00 g/mol

So the molar mass of compound = (12.01 × 10) + (1.01 × 12) + (14.01 × 2) + (16.00)

= 176.21 g/mol

Ans b)

1 mole or 163.94 g of Na3PO4 contains 3 moles of sodium ions.

So 18.9 g of Na3PO4 wil contain (18.9 x 3) / 163.94 = 0.346 moles of sodium ions.

1 mole = 6.022 × 10²³ ions

0.346 moles = 0.346 x 6.022 x 10²³

= 2.08 ×10²³ sodium ions