Chapter 7 Stoichiometry

Question 1

Three types of Technology

Answer 1

Industrial- Usually involves large scale production of substances from natural raw materials.
Commercial- medium scale processes involved in the production of goods at the level of individual business.
Consumer- involve the use, by individuals on a personal level, of products and processes.

Question 2

What do chemical reaction equations not describe or explain?

Answer 2

• pressure and temp. conditions under which reaction may occur. Assume SATP unless otherwise told.
• progress and process of reaction. Shows reactants and products but not the stages in between or the time the reaction may take.
• measurable quantities of reactants. Equation is equal in chemical entities so total mass cannot change- law of conservation of mass. For many reactions this information is not enough to interpret quantities.

Question 3

Four reaction assumptions

Answer 3

• Reactions are spontaneous. When reactants are mixed, reaction will occur
• Reactions are fast. Useful reactions must occur in a reasonable amount of time.
• Reactions are quantitative. More than 99% complete, at least one reactant is used up completely.
• Reactions are stoichiometric. There is a simple, whole-number ratio of chemical amounts of reactants and products

Question 4

What does a balanced equation directly communicate?

Answer 4

Reaction equations show the mole ratio of the reactants and products and indicate the state of the substances in the reaction.

Question 5

Net Ionic Equation

Answer 5

A chemical equation leaving out any entities that do not change the reaction

Question 6

Spectator Ion

Answer 6

Ions that are present but do not take part in (change during) the reaction

Question 7

Steps to writing a net ionic equation

Answer 7

1. Write a complete balanced chemical equation
2. Dissociate all high solubility ionic compounds and ionize all strong acids to show the complete ionic equation
3. Cancel identical entities that appear on both reactant and product sides
4. Write the net ionic equation, reducing coefficients if necessary

Question 8

Limiting Reagent

Answer 8

The reactant whose entities are completely consumed in a reaction. The reaction stops when- and because- all of the reactant is used up and none remains.

Question 9

Excess Reagent

Answer 9

The reactant whose entities are present in surplus amounts, so that some remain after the reaction ends. A greater amount than necessary is added to the reaction system to ensure the limiting reagent runs out first.

Question 10

Stoichiometry

Answer 10

The description of the relative quantities of the reactants and products by chemical amount (moles). Any measured quantity of any substance in a reaction must be based on the stoichiometry of the reaction.