Chemistry Reactions and Solutions

What is a precipitation reaction?

A reaction in which an insoluble solid forms from substances in solution.

What symbol indicates that a precipitate has formed?

(s)

Is AgNO₃(aq) + HCl(aq) → AgCl(s) + HNO₃(aq) a precipitation reaction?

Yes, because AgCl(s) is an insoluble solid.

What type of reaction is Mg(s) + O₂(g) → MgO(s)?

Synthesis (combination).

What type of reaction is Zn(s) + 2Ag⁺(aq) → 2Ag(s) + Zn²⁺(aq)?

Single-replacement and redox.

What is a double-displacement reaction?

A reaction in which two compounds exchange ions.

What usually causes a double-displacement reaction to occur?

The formation of a precipitate, gas, or water.

What is oxidation?

Loss of electrons and an increase in oxidation state.

What is reduction?

Gain of electrons and a decrease in oxidation state.

What does LEO say GER mean?

Loss of Electrons = Oxidation; Gain of Electrons = Reduction.

What makes a reaction a redox reaction?

At least one element's oxidation state changes.

What is the oxidation state of an element by itself?

0

What is oxygen's usual oxidation state?

−2

What is hydrogen's usual oxidation state when bonded to a nonmetal?

+1

What is nitrogen's oxidation state in NO₂?

+4

What is nitrogen's oxidation state in HNO₃?

+5

What is nitrogen's oxidation state in NH₄⁺?

−3

What is nitrogen's oxidation state in NO₂⁻?

+3

In H₂O + CO → H₂ + CO₂, which substance is oxidized?

CO, because carbon goes from +2 to +4.

In Mg + I₂ → MgI₂, what happens to Mg?

Mg is oxidized, going from 0 to +2.

In Mg + I₂ → MgI₂, what happens to iodine?

Iodine is reduced, going from 0 to −1.

What is a Brønsted-Lowry acid?

An H⁺ donor.

What is a Brønsted-Lowry base?

An H⁺ acceptor.

Which of these are strong acids: HCl, HNO₂, HBr, H₂SO₄, HClO₄?

HCl, HBr, H₂SO₄, and HClO₄.

Which of these is a weak acid: HCl, HBr, HNO₂, HClO₄?

HNO₂.

Which of these are strong bases: LiOH, NaOH, KOH, NH₃?

LiOH, NaOH, and KOH.

Which of these is a weak base: LiOH, NaOH, KOH, NH₃?

NH₃.

In H₃PO₄ + NH₃ → NH₄⁺ + H₂PO₄⁻, which substance is the acid?

H₃PO₄, because it donates H⁺.

In H₃PO₄ + NH₃ → NH₄⁺ + H₂PO₄⁻, which substance is the base?

NH₃, because it accepts H⁺.

What does ⇌ mean in a chemical equation?

The reaction is reversible and can reach equilibrium.

What is an electrolyte?

A substance that produces ions when dissolved in water.

What is a strong electrolyte?

A substance that produces ions essentially completely in water.

What is a weak electrolyte?

A substance that only partially produces ions in water.

What is a nonelectrolyte?

A substance that does not produce ions in water.

Is NaCl a strong electrolyte, weak electrolyte, or nonelectrolyte?

Strong electrolyte.

Is HCl a strong electrolyte, weak electrolyte, or nonelectrolyte in water?

Strong electrolyte.

Is CH₃COOH a strong electrolyte, weak electrolyte, or nonelectrolyte?

Weak electrolyte.

Is C₆H₈ an electrolyte or nonelectrolyte if it does not produce ions in water?

Nonelectrolyte.

What does aqueous (aq) mean?

The substance is dissolved in water.

What is a solution?

A homogeneous mixture of a solute and solvent.

What is a spectator ion?

An ion that does not participate in the actual chemical reaction.

Write the net ionic equation for Fe(NO₃)₃(aq) + KOH(aq).

Fe³⁺(aq) + 3OH⁻(aq) → Fe(OH)₃(s)

What are the spectator ions when Fe(NO₃)₃ reacts with KOH?

K⁺ and NO₃⁻.

What generally forms when a nonmetal oxide reacts with water?

An acid.

What generally forms when a metal oxide reacts with water?

A base.

What is the formula for mass percent?

Mass percent = (part ÷ whole) × 100

What is the mass percent of Fe in Fe₃O₄?

72.36%, or about 72%.

What is an isotope?

Atoms of the same element with the same number of protons but different numbers of neutrons.

What is the empirical formula of a compound containing 49.32% C, 43.84% O, and 6.85% H?

C₃H₅O₂

What are the steps for finding an empirical formula from percent composition?

Percent → grams → moles → divide by the smallest → multiply to get whole numbers.