How do you calculate the number of sodium ions, #Na^+#, in 14.2 g of sodium sulfate? [Relative atomic masses Na = 23, S = 32, O = 16]?

1 Answer
Oct 1, 2016

Answer:

Use the number of moles of sodium per mole of sodium sulfate.

Explanation:

Sodium sulfate is #Na_2##SO_4#
First, calculate the moles of sodium sulfate you have in a 14.2g sample.

  1. Find the molar mass of sodium sulfate
    molar mass = atomic mass in grams
    2(23) + 32 + 4(16) = 142 grams per mole
  2. Divide the mass of the sample by the molar mass to obtain moles
    #(14.2g)/(142gmol^-1)# = 0.1 mol

Now, for every 1 mol of #Na_2##SO_4# you have 2 moles of #Na^+# ions. Multiple the moles of #Na_2##SO_4# that you found just then by 2 to obtain the moles of sodium ions.

Use Avogadro's number (6.022 x #10^23#) to find the number of ions present. (Recall that Avogrado's number is the number of particles per mole of a substance).

6.022 x #10^23# x 0.2 mol = 1.2044 x #10^23# ions