Chemistry Chapter on Titration and Solutions
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Questions and Answers

What drives irreversible reactions in qualitative analysis to completion?

  • Higher concentration of reactants
  • The presence of water
  • Increased reaction temperature
  • Formation of insoluble or gaseous products (correct)

    • Which flame color is associated with the presence of sodium ions (Na⁺)?

  • Crimson red
  • Pale violet
  • Bright yellow (correct)
  • Green or blue

    • What type of solutions have particle sizes less than 500 nm and appear homogeneous?

  • True solutions (correct)
  • Emulsions
  • Suspensions
  • Colloids

    • According to Raoult's Law, what does the vapor pressure of a solution depend on?

    <p>Mole fraction of the solvent</p> Signup and view all the answers

    Which of the following factors does NOT affect the rate of solubility?

    <p>Color of the solute</p> Signup and view all the answers

    Which metal ion is characterized by a brick red or orange-red flame coloration?

    <p>Calcium (Ca²⁺)</p> Signup and view all the answers

    What is the pH at the equivalent point when titrating a strong acid with a strong alkali?

    <p>7</p> Signup and view all the answers

    Which indicator is commonly used for titrating strong acids with strong alkalis?

    <p>Methyl Orange</p> Signup and view all the answers

    During the titration of a strong base with a strong acid, what color does the solution start with?

    <p>Yellow</p> Signup and view all the answers

    What happens to the salt formed during the titration of a weak acid with a strong alkali?

    <p>It hydrolyzes.</p> Signup and view all the answers

    What is the molarity (M) formula in volumetric analysis?

    <p>M = n / V</p> Signup and view all the answers

    What is the percent concentration (C%) formula for solutions?

    <p>C% = mass of solute / total mass × 100%</p> Signup and view all the answers

    What is the primary characteristic of the salt formed when titrating acetic acid with sodium hydroxide?

    <p>It undergoes hydrolysis.</p> Signup and view all the answers

    In volumetric analysis, what does normality (N) represent?

    <p>Equivalent of solute per liter.</p> Signup and view all the answers

    What does phenolphthalein indicate during titration?

    <p>Transitions from acidic to basic.</p> Signup and view all the answers

    What is a standard solution?

    <p>A solution of known concentration, stable and reactive.</p> Signup and view all the answers

    What does the equivalence point in a titration indicate?

    <p>The reactants have completely reacted with no excess.</p> Signup and view all the answers

    Which equation represents the relationship at the equivalence point?

    <p>$Cn1 * V1 = Cn2 * V2$</p> Signup and view all the answers

    How is the concentration of titrated solutions calculated?

    <p>By the equation $Cn = m / E * V$.</p> Signup and view all the answers

    Which reaction forms a neutral solution at pH 7?

    <p>Strong acid + Strong base</p> Signup and view all the answers

    In a neutralization reaction, what ions are directly involved?

    <p>H+ and OH-</p> Signup and view all the answers

    What type of reaction occurs between a strong acid and a weak base?

    <p>Produces a salt and water with an acidic pH.</p> Signup and view all the answers

    Which of the following is NOT a common characteristic of a standard solution?

    <p>Reactivity with all types of substances</p> Signup and view all the answers

    When titrating a strong acid with a strong base, what is expected at the endpoint of the titration?

    <p>A color change due to an indicator.</p> Signup and view all the answers

    What defines the equivalence point in a titration?

    <p>The product of the titrant’s concentration and volume equals the product of the analyte’s concentration and volume</p> Signup and view all the answers

    What is the coordination number in Werner’s coordination theory?

    <p>The total number of atoms, ions, or molecules bonded to the central atom</p> Signup and view all the answers

    Which ion is primarily responsible for temporary water hardness?

    <p>Ca(HCO3)2 from dissolved bicarbonates</p> Signup and view all the answers

    What is EDTA primarily used for?

    <p>As a chelating agent to form stable complex compounds</p> Signup and view all the answers

    What is indicated by a complex's nomenclature that begins with 'di-'?

    <p>The presence of two ligands bonded to the central atom</p> Signup and view all the answers

    What is the main cause of permanent water hardness?

    <p>Dissolution of sulfates and chlorides of calcium or magnesium</p> Signup and view all the answers

    Which of the following is a characteristic of a coordinative bond?

    <p>It involves sharing of electrons from only one atom</p> Signup and view all the answers

    Which salt is responsible for temporary water hardness?

    <p>Mg(HCO3)2</p> Signup and view all the answers

    What do the terms 'primary valency' and 'secondary valency' refer to in coordination compounds?

    <p>Oxidation states and coordination numbers</p> Signup and view all the answers

    What is a characteristic of complexonates formed by chelating agents?

    <p>They form stable compounds with metal ions</p> Signup and view all the answers

    What is the cause of temporary water hardness?

    <p>Dissolved bicarbonates</p> Signup and view all the answers

    Which of the following formulas accurately represents the calculation of total hardness?

    <p>Total Hardness = Permanent Hardness + Temporary Hardness</p> Signup and view all the answers

    Which reaction demonstrates oxidation?

    <p>2Na → 2Na+ + e–</p> Signup and view all the answers

    How is permanent water hardness determined?

    <p>By subtraction of temporary hardness from total hardness</p> Signup and view all the answers

    Which of the following processes cannot remove permanent hardness?

    <p>Boiling</p> Signup and view all the answers

    What do redox reactions involve?

    <p>Changes in oxidation numbers</p> Signup and view all the answers

    Which of the following is a method of redoximetry?

    <p>Potassium permanganate titration</p> Signup and view all the answers

    In the given reaction, which species is reduced? Cl2 + 2e– → 2Cl–

    <p>Cl2</p> Signup and view all the answers

    What is represented by a decrease in oxidation number during a chemical reaction?

    <p>Reduction</p> Signup and view all the answers

    What type of reaction is characterized by irreversible changes?

    <p>Irreversible reactions</p> Signup and view all the answers

    Study Notes

    Standard Solutions

    • A reagent of known concentration, stable and reactive
    • Prepared by dissolving accurate weight of pure reagent in water and diluting to known volume
    • Concentration determined by dissolving pure reagent in water and diluting to exact volume

    Titrated Solutions

    • Solutions with approximate concentration
    • Prepared from unstable or reactive materials
    • Exact concentration is determined by titration with a standard solution

    Neutralization Titration

    • Method involving a reaction between an acid and a base resulting in a neutral solution at pH 7 (for strong acid-strong base reactions)
    • Equivalence point: The point where reactants have completely reacted with no excess.
    • At the equivalence point: Cn1 * V1 = Cn2 * V2 where Cn represents normality and V represents volume.

    Concentration Calculation

    • Concentration (normality, Cn) can be calculated by the equation Cn= m / E*V where m is the solute mass, E is the equivalent weight, and V is the solution volume
    • Neutralization titration: reaction between an acid and a base which produces a neutral solution (pH=7)
    • The general reaction is: acid+ + base– → salt + water

    Titration Curves & Indicators

    • Strong acid titrated with strong alkali (e.g., HCl + NaOH → NaCl + H2O)
      • Equivalent point pH=7
      • No hydrolysis of salt
      • Indicator: Methyl Orange
    • Strong alkali titrated with strong acid (e.g., 2 NaOH + 2 HCl = 2 NaCl + 2 H2O)
      • Equivalent point pH=7
      • No hydrolysis of salt
      • Indicator: Methyl Orange
    • Weak acid titrated with strong alkali (e.g., CH3COOH + NaOH → CH3COONa + H2O)
      • Equivalent point pH>7
      • The salt is hydrolyzed
      • Indicator: Phenolphthalein

    Expression of Concentration

    • Molarity (M): Number of gram moles of reagent contained in one liter solution (mol/L)
    • Normality (N): Number of gram equivalents contained in one liter of solution.
    • Percent concentration (C%): Grams of material dissolved in 100 grams of solution
    • Titer: Number of solute’s grammes in one cm3 (ml) of the solution (g/cm3 )

    Complex Compounds

    • The formula of complex ions is out in square brackets, and it is placed at the front if its charge is positive
    • The name of complex cations starts with the greek prefix for the coordination number (e.g., mono-, di-, tri-, and etc) followed by the name of the ligand, and the name of the metal ion with valence state indicated

    Werner’s Coordination Theory

    • Metals in coordination compounds exhibit primary valency (oxidation state) and secondary valency (coordination number)
    • These secondary valencies are spatially directed, leading to specific geometries.

    Complexometry

    • Complexone: Any chelating agent used for the analytical determination of metals
    • Chelating agents form stable complex compounds, called complexonates, with numerous ions of metals
    • EDTA (ethylene- diammine tetraacetic acid) is commonly used as a complexone
    • Trilon B: Salt of EDTA (disodium ethylenediaminetetraacetate)

    Water Hardness

    • Classified as temporary or permanent
    • Temporary Hardness (Carbonate Hardness): Caused by Ca(HCo3)2 and Mg(HCo3)2 dissolved in water
    • Permanent Hardness (Non-carbonate Hardness): Mainly caused by Ca2+/ Mg2+ sulfates, chlorides, silicates, phosphates and nitrates.

    Water Softening

    • Process of removing calcium, magnesium, and sometimes iron ions.

    Determining Water Hardness

    • Temporary Hardness: Can be removed by boiling and measured by titration
    • Permanent Hardness: Found by subtracting temporary hardness from total hardness
    • Total Hardness: Measured directly via EDTA titration

    Oxidation-Reduction (Redox) Processes

    • Reactions involve changes in oxidation numbers, where oxidation is the loss of electrons (increase in oxidation number) and reduction is the gain of electrons (decrease in oxidation number)

    Redox Equations

    • Redox reactions combine both an oxidation and a reduction into a single reaction

    Redoximetry

    • Methods are classified based on whether they use oxidizing or reducing agents in titration

    Qualitative Analysis

    • Irreversible reactions: Proceed to completion, often driven by the formation of products that are insoluble, gaseous, weak electrolytes or complex compounds
    • Analytical reactions in electrolyte solutions: Produce distinct observable changes known as analytical signals that include the presence of certain ions
    • Flame tests: Detect the presence of certain metal ions based on the color they impart to a flame.

    Solutions

    • Classified based on particle size and state
    • True solutions have particles < 1nm and are homogenous
    • Colloids have particles between 1nm and 500nm and are heterogenous
    • Suspensions have particles > 500 nm and are heterogenous

    True Solutions

    • Solubility: Factors related to solubility include temperature, pressure, and the nature of the solute and solvent
    • Factors affecting the “rate” of solubility include surface area, stirring, and temperature
    • Concentration of solutions: Mass percent solution, Molarity, Molality, Mole fraction

    Physical Properties of True Solutions

    • Vapor pressure: In a solution, the presence of a non-volatile solute reduces the solvent vapor pressure compared to its pure state
    • Raoult’s Law: For ideal solutions, the vapor pressure of the solution (Psolution) is directly proportional to the mole fraction of the solvent (X solvent) in the solution
    • Melting point: The melting point of a solution is lower than the melting point of the pure solvent
    • Boiling point: The boiling point of a solution is higher than the boiling point of the pure solvent
    • Osmotic pressure: The pressure that needs to be applied to a solution to prevent the inward flow of water across a semipermeable membrane.

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    Chemistry 1st Assessment PDF

    Description

    Test your knowledge on standard solutions, titrated solutions, and the principles of neutralization titration. This quiz covers concepts like concentration calculations and the equivalence point in titrations. Enhance your understanding of these essential chemistry topics.

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