Chapter 12- Stoichiometry

Question 0

What is Stoichiometry?

Answer 0

It’s calculating chemical quantities.

Question 1

What is a ratio?

Answer 1

It’s a balanced equation that shows us how much reactant is needed or how much product will be made.

Question 2

What is Stoichiometric coefficients?

Answer 2

The number before each atom/molecule in a chemical equation.

Question 3

What is the relationship between a balanced equation and a ratio?

Answer 3

A balanced equation will use ratios to show how much of a representative particle (or mole) is being reacted/produced in a reaction.

Question 4

Atom/Molecule x = subscript (eg H2 is helium.)
Interpret the equation in terms of numbers of representative particles, number of moles, and masses of reactants and products.
2K (s) + 2H2O (l) —-> 2KOH (aq) +H2 (g).

Answer 4

B

Question 5

Balance
C2H5OH (l)+ O2 —-> CO2 (g) + H*2O (g)
Show the balanced equation obeys the law of conservation of mass.

Answer 5

B

Question 6

What is the purpose of a mole ratio?

Answer 6

They are used to convert between any reactant or product to a different reactant or product in the same balanced equation.

Question 7

How do you do a mole-to-mole ratio?

Answer 7

G= given
W= wanted

G x __ mol W/ __ mol G= mol W.

Question 8

4AL (s) + 3 O2 (g) —> 2Al2O*3 (s)

A) Write the six mole ratios that can be derived from this equation.

B) How many moles of Aluminum are needed to form 3.7 mol Al2O3?

Answer 8

B

Question 9

4Al (s) + 3O2 (g) —-> 2Al2O*3 (s).

A) how many moles of oxygen are required to react completely with 14.8 mol Al?

B) how many moles of Al2O3 are formed when 0.78 mol O*2 reacts with aluminum?

Answer 9

B

Question 10

How dk you convert from mass to mass?

Answer 10

G x __ mol G / periodic mass G x __ mol W / __ mol G x periodic mass W / ___ mol W = ____ g W

Question 11

Acetylene gas (C*2H*2) is produced by adding water to Calcium carbide (CaC*2).
CaC*2 (s) + 2H*2O (l) ---> C*2H*2 (g) + Ca(OH) *2 (aq)

How many grams of acetylene are produced by adding water to 5 g CaC*2?

Answer 11

B

Question 12

CaC2 (s) + 2H2O (l) —> C2H2 (g) + Ca(OH)*2 (aq)

How many moles of CaC2 are needed to react completely with 49 g H2O?

Answer 12

B

Question 13

Define Theoretical Yield.

Answer 13

It’s the maximum amount of product that could be produced from given amounts of reactants.

Question 14

What is Actual yield?

Answer 14

It’s the amount of product that actually forms when the reaction is carried out in a lab.

Question 15

What is Percent Yield?

Answer 15

Percent Yield = Actual Yield / Theoretical Yield x 100%.

Question 16

Define a Limiting Reagent.

Answer 16

A Limiting Reagent is the reactant that determines the amount if product that can be formed by a reaction.

Question 17

Describe Excess Reagent.

Answer 17

It’s the reactant that is not used up completely in a reaction.