Stoichiometry Scaffolding

A balanced chemical equation allows one to determine the

• mole ratio of any two substances in the reaction.

• energy released in the reaction.

• electron configuration of all the elements in the reaction.

• mechanism involved in the reaction.

Tags

NGSS.HS-PS1-7

The coefficients in a chemical equation represent the

• masses, in grams, of all reactants and products.

• relative numbers of moles of reactants and products.

• number of atoms in each compound in a reaction.

• number of valence electrons involved in the reaction.

In the equation 2Al₂O₃ ----> 4Al + 3O₂, what is the mole ratio of aluminum to oxygen?

• 10:6

• 3:4

• 2:3

• 4:3

Tags

NGSS.HS-PS1-7

Fewer steps are required to solve stoichiometric problems when

• the reactant is given in grams and the product is sought in grams.

• the reactant is given in moles and the product is sought in moles.

• the reactant is given in grams and the product is sought in moles.

• the reactant is given in moles and the product is sought in grams.

All stoichiometry problems must include

• a gram to mole conversion factor.

• a mole to gram conversion factor.

• a mole to gram & a gram to mole conversion factor.

• a mole ratio.

A gram to gram stoichiometry problem must include

• a gram to mole conversion factor

• a mole to gram conversion factor

• a gram to mole & a mole to gram conversion factor.

• two gram to mole conversion factors.

One important component of gasoline mixtures is octane. The combustion of octane is represented in this equation:

2C₈H₁₈ + 25O_{2 ---->} 16CO₂ + 18H₂O. How many moles of oxygen are required to burn 0.40 moles of octane?

• 5 moles O₂

• 7.5 moles O₂

• 10 moles O₂

• 25 moles O₂

Gas grills use propane fuel. The combustion of propane is represented in this equation:

C₃H₈ + 5O_{2 ---->} 3CO₂ + 4H₂O. How many grams of propane will burn when 36.0 moles of water are formed?

• 0.500 g C₃H₈

• 9.00 g C₃H₈

• 318 g C₃H₈

• 397 g C₃H₈

The amount of significant figures used in the answer of a stoichiometry calculation are based upon

• the number of significant figures in the given.

• the integers in the mole ratio.

• the number of significant figures in the molar mass of the given substance.

• the number of significant figures in the molar mass of the unknown substance.

Every number in a stoichiometry calculation must be labeled with

• the substance's unit.

• the identity of the substance.

• both the unit and identity of the substance.

• its molar mass.

Tags

NGSS.HS-PS1-7