unit 7 - molar relationships

day 1 : idk

day 2 : idk

• calculate the number of grams of NH₃ produced by the reaction of 3.4 grams of hydrogen with an excess of nitrogen

• N₂(g) + 3H₂(g) → 2NH₃(g)

• gH₂ → molH₂ → molNH₃ → g NH₃

day 3 : percent yield??

you may need to analyze your results

• you may have to find the percent yield

• the theoretical yield is what is mathematically supposed to happen

• the actual yield is what is created in a real-world setting. sometimes, things do not work out according to plan - the actual yield is a reflection of this.

actual yield divided by theoretical yield * 100 = percent yield !

what happens when you have more than 1 reactant?

• when we have multiple reactants, we can get multiple answers

• what you have to do is solve the problem starting with both values for reactants, and identify the smallest answer as being better

• the smaller answer is called the theoretical yield. the reactant that gives you the theoretical is the limiting reagent, as it’s the reactant that you will run out of.

• the larger answer is the excess reagent. you will have more than enough, or, excess, of the reactant to complete the reaction.

sandwich example !

• to make a sandwich, you need 2 bread, 1 meat, and 1 cheese

  • 2B + 1M + 1C → 1S

• if you have 14 pieces of bread, 8 pieces of meat, and 5 pieces of cheese, how many sandwiches can you make ?

  • 5 sandwiches - cheese is our limiting reagent.

  • meat is the excess reagent.

• when solving problems - always go to moles of the SAME PRODUCT to compare which makes less