Formulas and Naming
% Composition & Formula Mass
Empirical and Molecular Formulas
Equations
Moles
100
What is the total number of oxygen atoms in the formula MgSO4 • 7 H2O?
11
100
What is the gram-formula mass of Ca(OH)2?
74 g/mol
100
Which formula is an empirical formula?
A) N2O4
B) NH3
C) C3H6
D) P4O10
B) NH3
100
Which type of chemical reaction is represented by the equation?
F2(g) + 2KCl(aq)-->2KF(aq) + Cl2(g)
Single Replacement
100
What is the mass of 1.5 moles of CO2?
66 g
200
Write the formula for sodium sulfate
Na2SO4
200
What is the gram formula mass of Mg(ClO3)2?
191 g
200
Given two formulas representing the same compound:
Formula A CH3 Formula B C2H6
Which statement describes these formulas?
A) Formulas A and B are both empirical.
B) Formulas A and B are both molecular.
C) Formula A is empirical, and formula B is molecular.
D) Formula A is molecular, and formula B is empirical.
C) Formula A is empirical, and formula B is molecular.
200
Which type of reaction does this equation represent?
2NaCl-->2Na + Cl2
decomposition
200
One mole of O2 has approximately the same mass as one mole of
A) CH4
B) S
C) LiH
D) Cl2
B) S
300
Write the formula for aluminum iodide
AlI3
300
What is the gram-formula mass of Fe(NO3)3?
242 g/mol
300
What is the empirical formula for a compound with the molecular formula C6H12Cl2O2?
C3H6ClO
300
The coefficients in a balanced chemical equation represent
A) the mass ratios of the substances in the reaction
B) the mole ratios of the substances in the reaction
C) the total number of electrons in the reaction
D) the total number of elements in the reaction
B) the mole ratios of the substances in the reaction
300
What is the number of moles of CO2 in a 220.-gram sample of CO2 (gram-formula mass = 44 g/mol)?
5.0 mol
400
What is name for the compound NaClO3
sodium chlorate
400
Show a numerical setup for calculating the percent composition by mass of oxygen in Al2O3 (gram-formula mass = 102 g/mol).
48/102 x 100
400
What is the empirical formula of a compound that has a carbon-to-hydrogen ratio of 2 to 6?
A) CH3
B) C2H6
C) C3H
D) C6H2
A) CH3
400
Which chemical equation is correctly balanced?
A) H2(g) + O2(g) → H2O(g)
B) N2(g) + H2(g) → NH3(g)
C) 2NaCl(s) → Na(s) + Cl2(g)
D) 2KCl(s) → 2K(s) + Cl2(g)
D) 2KCl(s) → 2K(s) + Cl2(g)
400
What is the number of moles in a 78.8-gram sample of MgCO3 (gram-formula mass = 84.3 g/mol)?
0.935 mol
500
A correct name for N2O3 is
A) nitrogen (I) oxide
B) nitrogen (II) oxide
C) nitrogen (III) oxide
D) nitrogen (IV) oxide
C) nitrogen (III) oxide
500
Show a numerical setup for calculating the percent composition by mass of chlorine in PCl3
106/137 x 100
500
Write the empirical formula of the solid reactant in the equation.
P2O5
500
Balance the equation:
500
What is the mass in grams of 2.0 moles of NO2?
92