Introduction to Stoichiometry

Stoichiometry is the branch of chemistry that deals with elements in compounds and with reactants and products in chemical reactions, focusing on

• a. bonding.

• b. energy transfers.

• c. mass relationships.

• d. physical characteristics.

Tags

NGSS.HS-PS1-7

Reaction stoichiometry is based on chemical equations and

• a. the law of conservation of mass.

• b. the ideal gas law.

• c. the law of conservation of momentum.

• d. Avogadro’s number.

The chemical equation P4O10 + 6H2O --> 4H3PO4 can be interpreted correctly as

• a. 1 molecule of P4O10 + 6 molecules of H2O form 4 molecules of H3PO4.

• b. 1 mol of P4O10 + 6 mol of H2O reacts to form 4 mol of H3PO4.

• c. 1 g of P4O10 + 6 g of H2O produces 4 g of H3PO4.

• d. Both (a) and (b)

How many unique mole ratios can be obtained from the following chemical equation? (Don't forget to double your answer, since they can be in reverse too!)

Na₂S + Cd(NO₃)₂ --> 2NaNO₃ + CdS

• 1

• 4

• 8

• 12

In stoichiometry, molar mass is used to

• a. determine the mole ratio.

• b. balance a chemical equation.

• c. convert the amount in moles of one substance to an amount in moles of another substance.

• d. relate the mass of a substance to the amount in moles of that substance.

Molar mass can be used to relate

• a. mass of reactant to moles of reactant.

• b. moles of product to mass of product.

• c. mass of product to moles of product.

• d. All of the above

The number of significant figures in an answer to a stoichiometry problem is determined only by

• a. the number of significant figures in the mole ratio used to solve the problem.

• b. the number of decimal places in the molar masses of substances in the chemical equation.

• c. the number of significant figures of any measured quantities in the problem.

• d. the number of significant figures in the molar masses of substances in the chemical equation.

Tags

NGSS.HS-PS1-7

In the chemical reaction described by the equation

4Fe(s) + 3O2(g) --> 2Fe2O3(s),

the mole ratio of iron(III) oxide to iron is

• 1:1

• 1:2

• 2:3

• 4:1

In the reaction: HCl(aq) + NaOH(aq) --> H2O + NaCl(aq)

If you have 50. ml of a 0.10M solution of HCl, how many Liters of a 0.10M solution of NaOH would react with this?

• a. 0.10 L

• b. 50. L

• c. 0.50 L

• d. 0.050 L

In the chemical equation A + 2B -->  C + 3D, if you know the number of moles of A that react, you can determine

• a. the number of moles of each reactant and product.

• b. the number of moles of B only.

• c. the total number of moles of C and D only.

• d. the total number of moles of A and B only.