Chemistry Final Exam

For the reaction represented by the equation Pb(NO3)2 + 2KI PbI2 + 2KNO3, how many moles of lead(II) iodide are produced from 300. g of potassium iodide and an excess of Pb(NO3)2? a. 0.904 mol b. 1.81 mol c. 3.61 mol d. 11.0 mol

a. 0.904 mol

To determine the limiting reactant in a chemical reaction, one must know the a. available amount of one of the reactants. b. amount of product formed. c. available amount of each reactant. d. speed of the reaction.

a. available amount of one of the reactants.

A chemical equation is balanced when the a. coefficients of the reactants equal the coefficients of the products. b. same number of each kind of atom appears in the reactants and in the products. c. products and reactants are the same chemicals. d. subscripts of the reactants equal the subscript

a. coefficients of the reactants equal the coefficients of the products.

In the chemical equation wA + xB yC + zD, if one knows the mass of A and the molar masses of A, B, C, and D, one can determine a. the mass of any of the reactants or products. b. the mass of B only. c. the total mass of C and D only. d. the total mass of A and B only.

a. the mass of any of the reactants or products

In the reaction represented by the equation N2 + 3H2 2NH3, what is the mole ratio of nitrogen to ammonia? a. 1:1 b. 1:2 c. 1:3 d. 2:3

b. 1:2

The coefficients in a chemical equation represent the a. masses, in grams, of all reactants and products. b. relative numbers of moles of reactants and products. c. number of atoms in each compound in a reaction. d. number of valence electrons involved in the reaction.

b. relative numbers of moles of reactants and products.

In the equation 2KClO3 2KCl + 3O2, how many moles of oxygen are produced when 3.0 mol of KClO3 decompose completely? a. 1.0 mol b. 2.5 mol c. 3.0 mol d. 4.5 mol

d. 4.5 mol

For the reaction represented by the equation Mg + 2HCl H2 + MgCl2, calculate the percentage yield of magnesium chloride if 100. g of magnesium react with excess hydrochloric acid to yield 330. g of magnesium chloride. a. 71.8% b. 74.3% c. 81.6% d. 84.2%

d. 84.2%

Which reactant controls the amount of product formed in a chemical reaction? a. excess reactant b. mole ratio c. composition reactant d. limiting reactant

d. limiting reactant

In what kind of reaction do two or more substances combine to form a new compound? a. decomposition reaction b. combustion reaction c. double-displacement reaction d. synthesis reaction

d. synthesis reaction