Question

A 0.1 M Solution of Na2SO4 contains

A. 9.6 x 10^3 mg/L SO4^-2

B. 4.6 x 10^6 ppb NA+

C. 14.2. g/L sodium sulfate

D. 0.3 mol/L ions

e. all of these choices are correct

Answer 1

e. all of these choices are correct

0.1 M Solution of Na2SO4 means 0.1 moles of solute in one liter

and Na2SO4 can dissociate in to 2Na⁺ + SO₄^2-

so molarity of Na+ = 2 x 0.1 = 0.2 M

molarity of SO42- = molarity of Na2SO4 = 0.1M

now comming to the options

first option 9.6 x 10³ mg/L convert mg to grams = 9.6 g/L

9.6 g/L means caculate the molarity

M = (9.6/ 96)/1 = 0.1M = 0.1M Na2SO4

second option

ppb means part per billion convert in to grams = 4.6 grams

M = 4.6 / 23. = 0.2 M but two Na+ ions are there so 0.2/2 = 0.1M

third option

14.2 gram/L Na2SO4

M = 14.2 / 142 = 0.1

fourth option

0.3 moles of ions

1 mole Na2SO4 can have3 moles of ions

0.1 moles of Na2SO4 can have 0.3 moles of ions