A sample of sodium carbonate Na COs weighs 280 g Calculate t

A sample of sodium carbonate, Na COs, weighs 28.0 g. Calculate the following quantities. (a) moles of Na CO (b) number of Na2COs formula units (c) number of Nat ions (d) moles of Co, ions mol Na-CO (b) | | × 10, formula units Na2CO3 X 10Na ions mol Co,2

Solution

mass of Na2CO3 = 28.0 grams

molar mass of Na2CO3 = 106 gram/mole

a) number of moles of Na2CO3 = mass/molar mass = 28.0/106 = 0.264 moles

number of moles of Na2CO3 = 0.264 moles.

b) 1 mole of Na2CO3 contains Avagadro number of formula units

1 mole of Na2CO3 = 6.023x10^23 formula units of Na2CO3

0.264 moles of Na2CO3 = ?

                              = 0.264 x 6.023x10^23 = 1.59 x10^23 formula units of Na2CO3

number of formula units of Na2CO3 = 1.59x10^23

C)

Na2CO3 ------------ 2 Na+ + CO3-2

In Na2CO3 , 2 moles of Na+ ions

number Na+ ions in 2 moles = 2x6.023x10^23

number of Na+ ions in 0.264 moles = ?

                                               = 2x6.023x10^23x0.264 = 3.18 x10^23 ions

number of Na+ ions = 3.18x10^23 ions

d)number of moles of CO3-2 ions= 0.264 moles.