CHEM 1030 Chapter 4: Aqueous Reactions and Solution Stoichiometry

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CHEM 1030 Full Course Notes

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Solutions - homogeneous mixtures of two or more pure substances: the solvent is present in greatest abundance, all other substances are solutes. Dissociation: when an ionic substance dissolves in water, the solvent pulls the individual ions from the crystal and solvates them. Electrolytes strong acids, strong bases, soluble ionic salts: a substance that dissociates into ions when dissolved in water, a strong electrolyte dissociates completely when dissolved in water. Strong acids, strong bases, soluble ionic salts: a weak electrolyte only dissociates partially when dissolved in water, soluble ionic compounds tend to be electrolytes. Nonelectrolytes: a nonelectrolyte may dissolve in water, but it does not dissociate into ions when it does so, molecular compounds tend to be nonelectrolytes, except for acids and bases. Precipitation reactions: when one mixes ions that form compounds that are insoluble (as could be predicted by the solubility guidelines), a precipitate is formed. Metathesis (exchange) reactions: the ions in the reactant compounds exchange, or transpose, ions.

Related Questions

The Behavior of Substances in Water

Part 1:

Ammonia, NH₃, is a weak electrolyte. It forms ions in solution by reacting with water molecules to form the ammonium ion and hydroxide ion. Write the balanced chemical reaction for this process, including state symbols.
From everyday experience, you are probably aware that table sugar (sucrose), C₁₂H₂₂O₁₁, is soluble in water. When sucrose dissolves in water, it doesn’t form ions through any reaction with water. It just dissolves without forming ions, so it is a nonelectrolyte. Write the chemical equation for the dissolving of sucrose in water.
Both NH₃ and C₁₂H₂₂O₁₁ are soluble molecular compounds, yet they behave differently in an aqueous solution. Briefly explain why one is a weak electrolyte and the other is a nonelectrolyte.
Hydrochloric acid, HCl, is a molecular compound that is a strong electrolyte. Write the chemical reaction of HCl with water.
Compare the ammonia reaction with that of hydrochloric acid. Why are both of these substances considered electrolytes?
Explain why HCl is a strong electrolyte and ammonia is a weak electrolyte.
Classify each of the following substances as either ionic or molecular:

KCl
NH₃
CO₂
MgBr₂
HCl
Ca(OH)₂
PbS
HC₂H₃O₂

For those compounds above that, you classified as ionic, use the solubility rules to determine which are soluble.
The majority of ionic substances are solids at room temperature. Describe what you would observe if you placed a soluble ionic compound and an insoluble ionic compound in separate beakers of water.
Write the chemical equation(s), including state symbols, for what happens when each soluble ionic compound that you identified above is placed in water. Are these substances reacting with water when they are added to water?
How would you classify the soluble ionic compounds: strong electrolyte, weak electrolyte, or nonelectrolyte? Explain your answer.
Sodium chloride, NaCl, is a strong electrolyte, as is hydroiodic acid, HI. Write the chemical equations for what happens when these substances are added to water. m
Are NaCl and HI strong electrolytes because they have similar behavior in an aqueous solution? If not, describe, using words and equations, the different chemical process that takes place in each case.

Part 2:

You have two hypothetical molecular compounds, AX and AY. AX is a strong electrolyte and AY is a weak electrolyte. The compounds undergo the following chemical reactions when added to water.

AX (aq) + H₂O (l) → AH₂O⁺ (aq) + X⁻ (aq)

AY (aq) + H₂O (l) → AH₂O⁺ (aq) + Y⁻ (aq)

Explain how the relative amounts of AX ( aq ) and AY ( aq ) would compare if you had a beaker of water with AX and a beaker of water with AY.
How would the relative amounts of X⁻ ( aq) and Y⁻ ( aq) in the two beakers compare? Be sure to explain your answer.

indigolouse566

Why do ionic compounds dissolve well in water? Select all that are true.

Question 5 options:

Because water and ionic compounds are both polar

Water molecules have partial charges that attract the ions in the solid compound, causing it to dissociate into separated ions

Because organic compounds are nonpolar

Water molecules can surround an ion, and neutralize the ion's charge using either it's partial positive or negative side.

The individual ions are solvated by water molecules which stabilizes the ions

2. Which compound is soluble in ether but not soluble in aqueous sodium hydroxide?

Question 2 options:

	ArOH
	Ar
	ArCOOH

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When you have a two-layer mixture of water and tert-butyl methyl ether, what physical property of these liquids assures you that the ether is the top layer?

Question 4 options:

low density was my answer was

You perform each extraction twice, first with 1 mL and second with 0.15 mL. Why is the second extraction necessary?

Question 8 options:

	several small extractions is better than one large one
	to remove any orgnaic material contaninating tube 2
	to remove any remaining neutral compound

7. Which of the following reactions is not favorable?

Question 7 options:

	ArCOOH + NaOH â ArCOO^-Na⁺ + H₂O
	ArOH + NaHCO₃ â ArO^-Na⁺ + CO₂ + H₂O
	ArCOOH + NaHCO₃ â ArCOO^-Na⁺ + CO₂ + H₂O

9.Why is phenol more acidic than an aliphatic alcohol?

Question 9 options:

	Its conjugates baseâs negative charge is localized on the oxygen
	Phenols have a stronger O-H bond
	Only the phenol can form hydrogen bonds
	Its conjugated base is stabilized by resonance

Which aqueous base reacts with a carboxylic acid but not with phenol? Why?

Question 10 options:

	Sodium bicarbonate, it is a weaker base and will only react with strong acids
	Sodium hydroxide, it is a strong base and will only react with strong acids
	Sodium bicarbonate, it is a weak base and will only react with weak acids
	Sodium hydroxide, it is a strong base and will only react with weak acids

Part A A fuel cell differs from a battery because the current is being generated from a reduction-oxidation (redox) reaction in which the reactant is consumed. A classic example of a fuel cell is the phosphoric acid fuel cell (PAFC), which have been used in stationary power generators, buses, and even submarines. Fuel cells require an electrolyte (similar to batteries) to carry electrically charged species between the electrodes, and a PAFC utilizes phosphoric acid (H3PO4) as its electrolyte. Phosphoric acid has three acidic protons that can dissociate in water, as highlighted in red here: H3PO4. However, it is considered a weak acid because some of the acid will remain in molecular form when dissolved in water. Write the complete ionic equation that depicts the dissociation of the first proton for the weak acid phosphoric acid (H3PO4). Make certain you include all charges for any ions produced. Express you answer as a chemical equation including phases. Titrations as analytical neutralization reactions Neutralization reactions can occur between any combination of weak/strong acids and bases. When we want to determine the concentration of a base in solution, we can apply the concept of neutralization by reacting the base with a known amount of an acid in the presence of an indicator (a compound that changes color depending on the pH). This method of determining the concentration of a base is called acid-base titration, and it can also be used to determine the concentration of an acid by titrating it with a known amount of base. A common acid to use for titrations is potassium hydrogen phthalate (written as KHP or KHPh; do not confuse the P for phosphorus). The reason KHP is common is because it is solid at room temperature, and we can accurately mass the amount that is added to solution. As a soluble salt, KHP completely dissociates to form a potassium ion (K+) and an acidic hydrogen phthalate ion (HPâ), which is a weak acid that has only one acidic hydrogen. This ionization is depicted below. KHP(s) â K+(aq)+HPâ(aq) Although ionization (the formation of ions) occurs as a result of acid dissociation for most weak acids, KHP ionizes before acid dissociation occurs. In other words, HPâ is a weak acid ion. Part C If you wanted to determine how much KOH (potassium hydroxide; a strong base) was dissolved in water, you could titrate it with a known amount of KHP (potassium hydrogen phthalate; a weak acid) until a color change indicates that the base is completely neutralized. The molecular equation below depicts this neutralization reaction. KHP(aq)+KOH(aq)âK2P(aq)+H2O(l) Write the net ionic equation that depicts the neutralization of the base by potassium hydrogen phthalate. Instead of using the entire chemical formula of phthalate, use HPâ to represent the acidic hydrogen phthalate ion and P2â to represent the phthalate ion. Express your answer as a net ionic equation including phases.

CHEM 1030 Chapter 4: Aqueous Reactions and Solution Stoichiometry

CHEM 1030 Full Course Notes

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