Although we've done this lab before, this time we'll be looking at it in more detail. Now, we are trying to find the percent yield. Labs are just a combination of everything that we've already done. Just remember all the individual steps and watch as the things often talked about happpen before your eyes!
What is percent yield?
It's the amount of product produced in relation to the amount expected to be produced, expressed as a percent.
percent yield = actual amount(g)
predicted amount(g)
Notes:
In lab 6B, we were given the molarity and volume of the solutions. This reaction is a double replacement reaction which produces a precipitate.
In order to find the percent yield, we had to make several calculations.
Steps:
1) write a balanced equation for the reaction.
2) calculate the moles of each solution.
3) find the limiting reactant.
4) use the amount of limiting reactant to calculate the amount of the precipitate expected to be produced. (MUST USE THE AMOUNT OF PRECIPITATE BECAUSE NOT ALL THE REACTANTS WERE USED IN THE REACTION, SO, SOME REACTANTS WILL STILL BE LEFT WITH THE AQUEOUS NaCl.) This is your predicted amount.
5) Find the mass of the precipitate actually produced by subtracting the mass of the filter paper from the combined mass of the filter and precipitate.
6) Calculate the % yield using the numbers you just calculated.
Try this problem.
If 800. mL of 0.648 M Aluminum Chloride was reacted with 500. mL of 0.5 M hydrochloric acid, what is the percent yield of Aluminum Chloride?
Write a balanced chemical equation, find the number of moles per each reactant, find the limiting reactant and calculate the percent yield.
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