WGU D425 INTRODUCTION TO CHEMISTRY
OA COMPREHENSIVE STUDY GUIDE 2026
FULL QUESTIONS AND SOLUTIONS GRADED A+
• What is the equation for finding pH?.
Answer: pH = -log[H3O+] pH = -log[OH-] ^Take answer and solve using
equation: pH+pOH = 14
• What is the molar mass for NH4C2H3O2.
Answer: 1N: 1×14.01=14.01 H: 7×1.008=7.06 C: 2×12.01=24.02 O:
2×16.00=32.00 77.09 g/mol.
• Decomposition.
Answer: A single compound breaks down into two or more simpler
substances (AB -> A + B).
• Surface Tension.
Answer: Property of liquids.
• Average atomic mass.
Answer: Weighted average mass of isotopes of an element sum of all
values(atomic mass of isootope * decimal abundance)
• a substance has a mass of 42.10g. if the density of the substance is known to
be 2.431g/ml what volume of substance is present.
Answer: Density= Mass/Volume 17.31 4 Sig Figs
• Valence Electrons.
Answer: Electrons in the outermost shell.
• Elements.
Answer: Simplest substances, atoms of the same type grouped together,
cannot be broken down chemically.
• % By Mass.
Answer: Mass percentage of a component in a mixture.
, • What is the defintion of a base.
Answer: a substance that produces hydroxide ions in water
• what equation represents the reaction btwn aqueous sodium chloride and
aqueous lead (ll) nitrate to form aqueous sodium nitrate and solid lead (ll)
chloride.
Answer: 2NaCl(aq)+Pb(NO3)2(aq) → 2NaNO3(aq)+PbCl2(s)
• What is the volume of 12.54 mol of Kr at STP.
Answer: V=n×22.4 Lmol V=12.54 mol×22.4 Lmol V=281 L
• What is the equivalence of 1 atm?.
Answer: 760 mmHg 760 torr
• "King Henry Died Drinking Chocolate Milk Mmm Nuts".
Answer: Kilo Hecto Deca Deci Centi Milli Micro Nano
• Coefficient.
Answer: Indicates the number of molecules/atoms/moles of each substance
in a reaction.
• Tetrahedral.
Answer: 4 bonds, 0 lone pairs. Bond angle: 109.5°.
• Given the periodic table what is the relationship btwn electron negativity
and atomic number for halogen group 17.
Answer: Electronegativity decreases from top to bottom
• Compounds.
Answer: A substance made up of 2 or more different elements joined
together in a whole number ratio by chemical bonds.
• Common Conversions.
Answer: 1 meter = 100 centimeters.
• what is the balanced product of this equation: Pb(OH)4+H2SO4->
Pb(SO4)2+H2O.
Answer: Pb(HO)4+2H2SO4->Pb(SO4)2+4H2O Reactant: Pb=1 O=12 H=8
OA COMPREHENSIVE STUDY GUIDE 2026
FULL QUESTIONS AND SOLUTIONS GRADED A+
• What is the equation for finding pH?.
Answer: pH = -log[H3O+] pH = -log[OH-] ^Take answer and solve using
equation: pH+pOH = 14
• What is the molar mass for NH4C2H3O2.
Answer: 1N: 1×14.01=14.01 H: 7×1.008=7.06 C: 2×12.01=24.02 O:
2×16.00=32.00 77.09 g/mol.
• Decomposition.
Answer: A single compound breaks down into two or more simpler
substances (AB -> A + B).
• Surface Tension.
Answer: Property of liquids.
• Average atomic mass.
Answer: Weighted average mass of isotopes of an element sum of all
values(atomic mass of isootope * decimal abundance)
• a substance has a mass of 42.10g. if the density of the substance is known to
be 2.431g/ml what volume of substance is present.
Answer: Density= Mass/Volume 17.31 4 Sig Figs
• Valence Electrons.
Answer: Electrons in the outermost shell.
• Elements.
Answer: Simplest substances, atoms of the same type grouped together,
cannot be broken down chemically.
• % By Mass.
Answer: Mass percentage of a component in a mixture.
, • What is the defintion of a base.
Answer: a substance that produces hydroxide ions in water
• what equation represents the reaction btwn aqueous sodium chloride and
aqueous lead (ll) nitrate to form aqueous sodium nitrate and solid lead (ll)
chloride.
Answer: 2NaCl(aq)+Pb(NO3)2(aq) → 2NaNO3(aq)+PbCl2(s)
• What is the volume of 12.54 mol of Kr at STP.
Answer: V=n×22.4 Lmol V=12.54 mol×22.4 Lmol V=281 L
• What is the equivalence of 1 atm?.
Answer: 760 mmHg 760 torr
• "King Henry Died Drinking Chocolate Milk Mmm Nuts".
Answer: Kilo Hecto Deca Deci Centi Milli Micro Nano
• Coefficient.
Answer: Indicates the number of molecules/atoms/moles of each substance
in a reaction.
• Tetrahedral.
Answer: 4 bonds, 0 lone pairs. Bond angle: 109.5°.
• Given the periodic table what is the relationship btwn electron negativity
and atomic number for halogen group 17.
Answer: Electronegativity decreases from top to bottom
• Compounds.
Answer: A substance made up of 2 or more different elements joined
together in a whole number ratio by chemical bonds.
• Common Conversions.
Answer: 1 meter = 100 centimeters.
• what is the balanced product of this equation: Pb(OH)4+H2SO4->
Pb(SO4)2+H2O.
Answer: Pb(HO)4+2H2SO4->Pb(SO4)2+4H2O Reactant: Pb=1 O=12 H=8
