36 Questions
What is the primary purpose of a net ionic equation?
To eliminate the spectator ions and show only the actual chemical change
What is the definition of a precipitate?
An insoluble compound formed in a chemical reaction
What is the difference between precipitation and crystallization?
Precipitation forms small crystals, while crystallization forms large crystals
Which of the following statements is true about ionic compounds?
Some ionic compounds are soluble in water, while others are insoluble
What is the result of mixing a soluble Ag+(aq) solution with a soluble CrO42-(aq) solution?
An insoluble Ag2CrO4(s) precipitate forms
What is a characteristic of the solid formed in a precipitation reaction?
It is composed of very small crystals
What happens to the ions in a precipitation reaction when they are spectator ions?
They remain in solution as solvated ions
What is the purpose of writing a net ionic equation?
To show only the ions that participate in the reaction
Which of the following compounds is most likely to be insoluble in water?
SrF2
What is the result of mixing two solutions that contain soluble compounds with no precipitate forming?
The compounds remain in solution as solvated ions
What is the role of the molecular equation in a precipitation reaction?
To show the reactants and products in the reaction
What is the purpose of identifying the spectator ions in a precipitation reaction?
To identify the ions that do not participate in the reaction
What is the net ionic equation for the reaction described in the passage?
Zn2+ (aq) + 2Cl– (aq) → ZnCl2 (aq)
In the reaction, how many moles of Cl- ions are produced from 1 mole of ZnCl2?
0.058 moles
Which step in the preparation of molar solutions involves weighing the solid to the desired amount?
Step 1
What is the purpose of adding deionized water below the calibration mark in a volumetric flask?
To accurately dissolve the solute
What is the purpose of diluting a solution in chemistry?
To decrease the concentration to a lower molarity
What intervention ensures the thorough mixing of a solute in a volumetric flask during solution preparation?
Flipping the flask repeatedly with the stopper on
What is the characteristic of nitric acid that allows it to release one mole of H+ per mole of acid?
It is a strong acid.
What is the purpose of calculating the number of H+ ions in a solution of nitric acid?
To determine the number of moles of acid present.
What is a characteristic of strong acids?
They dissociate completely into ions in aqueous solution
What is the result of an acid-base reaction, also known as a neutralization reaction?
Production of water.
How many moles of H+ are released per mole of nitric acid in a solution?
One mole.
What is the primary reason for the dissociation of covalent compounds in water?
The properties of the water molecule
What is the type of reaction that occurs when an acid and a base react with each other?
Acid-base reaction.
What is the result of the interaction between H+ ions and water molecules in aqueous solution?
The formation of hydronium ions
What is the reason why nitric acid is considered a strong acid?
It completely dissociates in water.
Which of the following is an example of a weak acid?
H3PO4
What is the definition of a base in terms of its behavior in water?
A substance that produces OH- ions when dissolved in water
How many strong acids are discussed in this course?
6
What is the characteristic of a compound that contains the OH group in its formula?
It is always a base
What is the result of the reaction between an ionic oxide of group 1(A) and water?
The formation of a metal hydroxide and hydroxide ions
What is the characteristic of a strong base?
It dissociates completely into ions in aqueous solution
Which of the following is a weak base?
Ammonia, NH3
What is the characteristic of a weak acid or weak base in aqueous solution?
It dissociates partially into ions
Which of the following is an example of a heavy group 2A(2) hydroxide?
Barium hydroxide, Ba(OH)2
Study Notes
Net Ionic Equations
- A net ionic equation eliminates spectator ions and shows only the actual chemical change
- The electric charges on both sides of the equation must balance
- Example: 2Ag+ (aq) + CrO42– (aq) → Ag2CrO4 (s)
Precipitation Reactions
- A precipitation reaction occurs when two soluble ionic compounds react to form an insoluble product, called a precipitate
- A precipitate is an insoluble compound, either ionic or covalent
- Not all ionic compounds are soluble in water
- The resulting solid crystals from a precipitation reaction are very small (microcrystals)
- Example: 2Ag+ (aq) + CrO42– (aq) → Ag2CrO4 (s)
Molecular, Total Ionic, and Net Ionic Equations
- Molecular equation: 2KF (aq) + Sr(NO3)2 (aq) → 2KNO3 (aq) + SrF2 (s)
- Total ionic equation: 2K+ (aq) + 2F− (aq) + Sr2+ (aq) + 2NO3− (aq) → 2K+ (aq) + 2NO3− (aq) + SrF2 (s)
- Net ionic equation: Sr2+ (aq) + 2F− (aq) → SrF2 (s)
Laboratory Preparation of Molar Solutions
- Step 1: Weigh the solid to the desired amount on a weighing boat
- Step 2: Transfer the solid quantitatively to a volumetric flask
- Step 3: Add deionized water below the calibration mark and shake to completely dissolve the solute
- Step 4: Add deionized water to the final volume and shake the flask
Diluting a Solution
- Diluting: adding solvent to a solution of higher molarity to decrease the concentration to a lower molarity
Acid-Base Reactions
- Acid-base reactions always produce water
- Not all formulas with one or more H atoms are acids
- Acids are covalent compounds, not ionic
- Dissociation of dissolved covalent compounds is rare
- Strong acids: HCl, HNO3, H2SO4
- Weak acids: HF, HNO2, H2SO3, H3PO4
H+ Ion as a Solvated Hydronium Ion
- H+ interacts strongly with H2O, forming H3O+ in aqueous solution
- H3O+ ion further surrounds itself with H2O molecules in an interaction known as hydrogen bonding
Strong and Weak Acids
- Strong acids: HCl, HBr, HI, HNO3, H2SO4, HClO4
- Weak acids: HF, H3PO4, CH3COOH (or HC2H3O2), and all organic acids
Bases
- A base is a substance that produces OH- ions when dissolved in H2O
- Production of OH- ions can occur under different scenarios:
- A pure compound already contains the OH- group
- An ionic oxide of group 1(A) or group 2(A)
- Aqueous solutions of some covalent compounds, such as NH3
Strong and Weak Bases
- Strong bases: Group 1A(1) hydroxides, heavy Group 2A(2) hydroxides
- Weak bases: everything else, including NH3 and Mg(OH)2
Acids and Bases as Electrolytes
- Strong acids and strong bases dissociate completely into ions in aqueous solution and are strong electrolytes
- Weak acids and weak bases dissociate very little into ions in aqueous solution and are weak electrolytes
Test your understanding of net ionic equations and precipitation reactions with this quiz. Learn to eliminate spectator ions and balance electric charges in chemical changes.
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