Unit D: Stochiometry

Question 1

What 4 steps should I follow to answer a stoichiometry question?

Answer 1

1. Obtain a correctly balanced equation.
2. Determine the moles of your “given” substance. (n = m / M or n = CV or n = PV / RT)
3. Determine the amount of moles of your required substance (coefficient required / coefficient given x number of moles)

Question 2

What are the 4 steps to solve a gravimetric stoichiometry?

Answer 2

1. Obtain a correctly balanced equation.
2. Determine the moles of your “given” substance.
3. Determine the amount of moles of your required substance (nr = coefficient required / coefficient given x number of moles)
4. Use the moles of required to calculate the appropriate amount requested - (mr = nrMr in other terms: m = nM)

Question 3

How do I find percentage yield?

Answer 3

% yield = actual amount produced / theoretical amount produced x 100%

Question 4

How do I find percent error?

Answer 4

Theoretical amount - actual amount / theoretical amount x 100%

Question 5

What are the 4 steps to solve for gaseous stoichiometry?

Answer 5

1. Obtain a correctly balanced equation.

2. Determine the moles of your “given” substance (n = PV / RT) , (n = m / M) , or Molar Volume at STP or SATP , (n = CV)

Question 6

What are the steps to solve for volumetric stoichiometry?

Answer 6

1. Obtain a correctly balanced equation.
2. Determine the moles of your “given” substance: (n = CV or n = m/M)
3. Determine the amount of moles of your required substance (n = coefficient required / coefficient given x number of moles)

Question 7

What are limiting reagents?

Answer 7

The reactant that is completely consumed in the reaction. It gets all used up.

Question 8

What are excess reagents?

Answer 8

Any reactant that is left over after the limiting reagent has been used up.

Question 9

How do you find which reactant is limiting and which reactant is excess?

Answer 9

The small number of moles when putting it in the coefficients.

Question 10

What is a titration?

Answer 10

The technique involving the addition of a measured amount of one reactant.

Question 11

What are pH curves?

Answer 11

A graph that shows the continuous change of pH levels during an Acid-Base reaction. It is a graph of pH level versus the volume of titrant added.

Question 12

What is the endpoint?

Answer 12

A point of a titration in which a distinct change in a measurable property of the reaction occurs. In the case of Acid-Base titration it will be a drastic change in the pH and on the graph it is located at the midpoint of the sharp drop.

Question 13

What is the equivalence point?

Answer 13

It is the volume of the titrant added when the endpoint is reached. It is the volume that it is to be used in Stoichiometric calculations.