How many grams of sodium iodide, NaI, must be used to produce 23.3 g of iodine, I2?

Answer 1

I₂ has a molar mass of 253.8 g/mol

So, we first find how many moles of I₂ we want to produce:

23.3 g I₂ x 1 mol I₂ / 253.8 g = 0.0918 moles of I₂

We can look at the conversion of NaI to I₂ as something like 2NaI ==> 2Na + I₂ (even though this may not be the actual reaction). You can see it takes 2 moles of NaI to make 1 mole of I₂. Thus...

0.0918 moles I₂ x 2 moles NaI / mole I₂ = 0.1836 moles of NaI are needed.

Converting this to grams, we have...

0.1836 moles NaI x 150. g NaI / mole NaI = 27.5 g NaI would be needed