Question

A chemist reacted 17.25 grams of sodium metal with an excess amount of chlorine gas. The chemical reaction that occurred is shown.

Na + Cl2 → NaCl

If the percentage yield of the reaction is 88%, what is the actual yield? Show your work, including the use of stoichiometric calculations and conversion factors.

Answer 1

first, balance the equation. since you have 2 Cl atoms on the left but only 1 on the right, you can write a 2 in front of NaCl to get Na + Cl2 → 2NaCl. the sodium is now unbalanced, but that can be fixed by adding a 2 in front of Na to get

2Na + Cl2 → 2NaCl

as the complete balanced reaction.

from there, starting with your reactant 17.25g Na, divide by the molar mass of Na to get moles Na.

the equation tells us that 2 moles Na makes 2 moles NaCl, so the moles Na you got from the previous step is equal to the moles NaCl produced.

now you're in moles NaCl. multiply by the molar mass of NaCl to get grams. this is the theoretical yield of NaCl.

finally, the percent yield is 88%. simply multiply the theoretical yield by 88% to get the actual yield.