General Knowledge
What needs to happen to figure out the amount of product produced?
We must determine which reactant will limit the chemical reaction and which reactant is in excess.
What is a limiting reagent?
The reagent that is completely used up or reacted.
What is the theoretical yield?
The maximum amount of product that could be formed from given amounts of reactants.
A student obtained 2 moles of O2 as a product in an experiment. The theoretical yield is 72 grams of O2. What is the percent yield?
88.9%
Why are excess and limiting reagents important?
They let us know when the reaction cannot proceed and limits it from continuing.
What is one way of finding the limiting reagent?
By calculating the amount of product (grams or moles) that can be formed by each reactant
What is the actual yield?
The amount of product that actually forms when the reaction is carried out in the laboratory
The theoretical yield of beryllium chloride was 10.7 grams. If the reaction actually yields 4.5 grams, what was the percent yield?
42%
What happens when there isn't enough of one reactant in a chemical reaction?
The reaction stops abruptly.
Find the limiting reagent by looking at the number of _______ of each reactant.
moles
You need to make sure that an equation is ______ before finding the theoretical and actual yield.
balanced
LiOH + KCl --> LiCl + KOH
A scientist began this reaction with 20 grams of lithium hydroxide and an unlimited amount of KCl. What is the theoretical yield of lithium chloride (grams)?
35 grams LiCl
What is an excess reagent?
reactant that is not fully used up in the reaction. there is some of it left over at the end
Sodium and water react according to the reaction
2 Na + 2 H2O--> 2 NaOH + H2
What number of moles of H2 will be produced when 4 moles Na is added to 2 moles H2O?
1 mol
What is the equation you need to find percent yield?
actual yield / theoretical x 100
For the reaction
2Cl2 + 4NaOH --> 3NaCl + NaClO2 + 2H2O
11.9 g Cl2 is reacted with 12.0 g NaOH. Determine which is the limiting reactant.
NaOH
Chemical reaction equations give the ideal stoichiometric relationship among ______ and ______.
reactants, products
For the reaction
2 S + 3 O2 --> 2S03
if 6.3 g of S is reacted with 10.0 g of O2 which one will be the limiting reactant
Sulfur (S)
In the reaction between CO and Fe3O4 the theoretical yield in an experiment is calculated to be 47.2 g Fe. When a chemistry student carries out the experiment, the actual yield is 42.9 g Fe. Calculate the percent yield.
90.9 % yield
Consider the reaction
Mg2Si + 4 H2O --> 2 Mg(OH)2 + SiH4
Which of the reactants is in excess if we start with 50.0 g of each reactant?
H2O