What mass (in g) of sodium ions, Na+, are there in 25 mL of 0.75 M Na2SO3?

(A) 0.019g (B) 0.87g (C) 2.4 g (D) 4.8g

Solution:

Molarity= moles of solute/L of solution

Molarity = 0.75M

Volume = 25ml (1L/1000ml) = 0.025L

0.75M = moles of Na2SO3/ 0.025L

moles of Na2SO3 = 0.019 moles

0.019moles of Na2SO3 ( 2moles of Na+/ 1 mol of Na2SO3) (22.99g Na+/ 1 mol of Na+) = 0.87 g Na+

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