Question

Consider the reaction between sodium metal and chlorine gas to form sodium chloride (table salt): 2Na(s) + Cl2(g) → 2NaCl(s) If the mass of the sodium solid increases by 0.500 g, what mass of sodium metal should have reacted?

Answer 1

For reactions remember one thing moles ratio is most important

Take the example of 2 mole Na to react with 1 mole Cl2 to give 2 moles NaCl

This is the base ratio for this reaction and it won't change ever just the ratios change

2 mole Na + 1 mole Cl2 = 2mole NaCl

4 mole Na + 2 mole Cl2 = 4 mole NaCl

8 mole Na + 4 mole Cl2 = 8 mole NaCl

16 mole Na + 8 mole Cl2 = 16 mole NaCl

.

So if 2 mole Na reacts with 1 mole Cl2

Then if you increase the mass of Na by 0.500 grams ie 0.500/58.4 = 0.00856 moles then you need to increase the no of moles of Cl2 also so that again the ratio should remain the same

But in the above case, only Na moles were increased which meant that the extra amount added will remain unreacted.

The extra added amount will be left unreacted

The same mass which was before will react