Stoichiometry Review

One of the key steps in producing pure copper from copper ores is the reaction below:

Cu₂S (s) + Cu₂O (s) --> Cu (s) + SO₂ (g) (unbalanced)

After balancing the reaction, determine how many dozen copper atoms could be produced from a dozen molecules of the sulfide and two dozen of the oxide of copper(I). Also how many moles of copper could be produced from one mole of the sulfide and two moles of the oxide?

• 1 dozen and 1 mole

• 2 dozen and 2 mole

• 3 dozen and 3 mole

• 6 dozen and 6 mole

Carbon tetrachloride, CCl₄ (commonly called “carbon tet”), is

used extensively as a solvent in laboratories and in industry.

How many moles of Cl atoms are needed to react with 2.20

moles of carbon to produce CCl₄?

• 2.20 moles

• 4.00 moles

• 4.40 moles

• 8.80 moles

Tags

NGSS.HS-PS1-7

Propane, C₃H₆, is a common fuel used in heating homes in rural areas. Predict how many moles of CO₂ are formed when 3.74 moles of propane are burned according to

C₃H₆ + 6O₂ --> 3CO₂ + 6H₂O

• 11.2 moles

• 7.48 moles

• 3.74 moles

• 1.25 moles

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NGSS.HS-PS1-7

Zirconium is a metal that is used in the design of catalytic Converters, and that can be isolated from the carbide in a 2-step process:

ZrC + 4Cl₂ --> ZrCl₄ + CCl₄

ZrCl₄ + 2Mg --> Zr + 2MgCl₂

How many moles of Zr can be produced from 3.00 moles of Cl₂?

• 0.25 moles

• 0.75 moles

• 1.25 moles

• 4.00 moles

Tags

NGSS.HS-PS1-7

How many grams of oxygen are needed to react with 42.8 g of chromium in the production of Cr₂O₃, a common paint pigment?

• 42.8 g

• 33.4 g

• 19.8 g

• 10.5 g

Ammonium nitrate decomposes when heated to form “laughing gas,” N₂O, and water. If this reaction forms 36.0 g H₂O, how many grams of N₂O are also formed?

• 36.0 g

• 40.0 g

• 44.0 g

• 48.0 g

Acetylene burners are used in metal welding because acetylene (C₂H₂) flames are very hot. How many grams of calcium carbide are needed to produce 10.0 g C₂H₂?

CaC₂ + 2H₂O --> Ca(OH)₂ + C₂H₂

• 24.7 g

• 64.1 g

• 10.0 g

• 15.5 g

Tags

NGSS.HS-PS1-7

NGSS.HS-PS1-2

The Haber process is very important in industry because it converts atmospheric nitrogen into a more reactive form:

N₂(g) + 3H₂(g) --> 2NH₃(g)

How many moles of ammonia can theoretically be produced from a mixture containing 3.0 moles each of nitrogen and hydrogen?

• 1.0 mole

• 2.0 moles

• 3.0 moles

• 0.5 moles

How many grams of NH3 can be produced from the mixture of 3.0 g each of nitrogen and hydrogen by the Haber process?

N₂ + 3H₂ --> 2NH₃

• 2.0 g

• 3.0 g

• 3.6 g

• 6.0 g

Tags

NGSS.HS-PS1-7

Find the percent yield of product if 1.5 g of SO₃ is produced from 1.0 g of O₂ via the reaction:

2S + 3O₂ --> 2SO₃

• 75%

• 80%

• 88%

• 92%