Unit 1 Stoichiometry Test

What is the Law of Conservation of mass?

• Mass is created in a chemical reaction
• Mass is created in a physical change
• New chemicals formed from a chemical reaction have a larger overall mass than the original reactants
• Mass is never created or destroyed

If a reaction starts with a total 75g of reactants it should produce 

• a total of 40g of products
• a total of 75g of products
• a total of 180 g of products
• None of the above

Sodium and chlorine combine to form sodium chloride, or table salt. Sodium and chlorine are:

• Producers

• Products

• Reactionaries

• Reactants

What do we call the chemicals that result from a chemical reaction?

• reactants

• products

• subscripts

• coefficients

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

• 10:6 
• 3:4
• 4:3
• 2:3

What can be determined from a balanced chemical equation?

• Mole ratio of any two substances in the reaction
• Energy released in the reaction.
• Electron configuration of all elements in the reaction. 
• Mechanism involved in the reaction. 

What is the number before a chemical formula called?

Example: 2H₂ + O₂ ---> 2H₂O

• Coefficient

• Atom

• Subscript

• Equation

Mole Ratios used for conversions are derived from:

• the molar mass of the reactants in the balanced chemical equation

• the coefficients of the balanced chemical equation

• the subscripts of the products in the balanced chemical equation

• the group number of each element in the balanced chemical equation

The limiting reactant

• slows the reaction down
• is used up first
• is the reactant that is left over
• controls the speed of the reaction

When does a chemical reaction stop?

• When the lab is finished
• When the excess reactant is used up
• When the limiting reactant is used up
• Chemical reactions never stop