Chemistry Chapter on pH and Acids
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Questions and Answers

What is the pH of a 3.43 x 10-5 M solution of hydrochloric acid?

  • 4.46 (correct)
  • 5.52
  • 3.46
  • 6.80

What is the hydrogen ion concentration of a solution of HCl with a pH of 4.52?

  • 2.98 x 10-5 M
  • 3.02 x 10-5 M (correct)
  • 1.50 x 10-5 M
  • 4.74 x 10-5 M

What is the relationship between pKa and pKb?

  • pKa + pKb = 14 (correct)
  • pKa = pKb - 14
  • pKa x pKb = 14
  • pKa - pKb = Kw

If a solution has a pOH of 3.8, what is the pH?

<p>8.0 (D)</p> Signup and view all the answers

To achieve a desired pH of 4.50 with 0.20 M acetic acid (pKa = 4.76), what is needed?

<p>Add sodium acetate in a specific ratio (A)</p> Signup and view all the answers

Which of the following is considered an official water according to USP?

<p>Purified Waters (C)</p> Signup and view all the answers

What is the function of Sodium Nitrite in the context of antioxidants?

<p>Reducing agent (C)</p> Signup and view all the answers

Which of the following types of waters is specifically labeled for injection use?

<p>Sterile Water for Injection (C), Bacteriostatic Water for Injection (D)</p> Signup and view all the answers

Which acid is not associated with a strong ammonia solution?

<p>Acetic acid (A)</p> Signup and view all the answers

Which of the following waters is not classified as a type of mineral water?

<p>Sodium Bisulfite (A)</p> Signup and view all the answers

What is the relationship between the pH of a solution and the ionization of weak acids?

<p>Lower pH increases ionization of weak acids (D)</p> Signup and view all the answers

Which factor primarily affects the ability of drug molecules to cross biological membranes?

<p>Ionization of the drug molecules (B)</p> Signup and view all the answers

In the percent ionization formula for weak acids, which component represents the strength of the acid?

<p>pKa (B)</p> Signup and view all the answers

For which of the following drugs would increasing the pH of urine enhance its excretion during toxicity?

<p>Barbiturates (B)</p> Signup and view all the answers

Using the formula for % ionization of weak bases, what happens as the pH of a solution increases relative to the pKa?

<p>Percent ionization decreases (B)</p> Signup and view all the answers

What is the formula for calculating the percent ionization of weak acids?

<p>% ionized = (ionized / (ionized + unionized)) x 100 (D)</p> Signup and view all the answers

What is typically the charge of ionized drug molecules compared to their nonionized counterparts?

<p>Ionized molecules are polar, nonionized are nonpolar (B)</p> Signup and view all the answers

What concentration and pH conditions would yield a higher ionization for a weak acid?

<p>Low concentration and high pH (A)</p> Signup and view all the answers

What is one of the primary uses of sodium hydroxide?

<p>As a reaction starter with acids (D)</p> Signup and view all the answers

Which of the following statements about buffers is true?

<p>Buffers consist of a weak acid and its salt or a weak base and its salt. (C)</p> Signup and view all the answers

What is a notable characteristic of aqueous solutions of sodium hydroxide?

<p>They are strongly alkaline. (A)</p> Signup and view all the answers

What is one of the requirements for pharmaceutical buffer selection?

<p>The buffer should exhibit reasonable chemical stability. (B)</p> Signup and view all the answers

Which of the following buffers is a mixture of hydroxides?

<p>Soda Lime (B)</p> Signup and view all the answers

What concentration of sodium hydroxide is typically used for identity testing?

<p>1 in 25 (A)</p> Signup and view all the answers

Why is sodium hydroxide preferred over potassium hydroxide in certain cases?

<p>It is less deliquescent. (D)</p> Signup and view all the answers

Which substance is commonly used as an oral antacid?

<p>Sodium Bicarbonate (A)</p> Signup and view all the answers

What role does the pKa play in buffer systems?

<p>It indicates the ability to resist pH changes. (A)</p> Signup and view all the answers

What is a major caution when handling sodium hydroxide?

<p>It can cause tissue destruction. (C)</p> Signup and view all the answers

What is the primary purpose of sulfuric acid when used in lead poisoning treatment?

<p>To administer high amounts of phosphate (C)</p> Signup and view all the answers

What is a characteristic reaction of sulfuric acid when mixed with organic substances?

<p>It chars them by abstraction of water elements (D)</p> Signup and view all the answers

Which process involves conversion of sulfur to SO2 in the preparation of sulfuric acid?

<p>Lead Chamber Process (C)</p> Signup and view all the answers

What is the composition range of sulfuric acid as described?

<p>Not less than 94% and not more than 98% H2SO4 (C)</p> Signup and view all the answers

What occurs when barium chloride TS is added to a dilute solution of sulfuric acid?

<p>A white precipitate of barium sulfate forms (C)</p> Signup and view all the answers

How should sulfuric acid be mixed with other liquids?

<p>Always add sulfuric acid to the diluent with caution (A)</p> Signup and view all the answers

What distinguishes sulfuric acid from thiosulfates in tests?

<p>Sulfuric acid reacts with lead acetate to form no precipitate. (A)</p> Signup and view all the answers

What is fuming sulfuric acid also known as?

<p>Oleum (A)</p> Signup and view all the answers

What is the primary use of sodium bisulfite?

<p>As an antioxidant in injectable preparations (D)</p> Signup and view all the answers

Which of the following methods can be used to prepare sulfur dioxide?

<p>Roasting sulfide ores (C)</p> Signup and view all the answers

What describes the physical state of sodium metabisulfite at room temperature?

<p>White crystals or yellowish powder (A)</p> Signup and view all the answers

Which ion is tested for identity using acid to litmus?

<p>Hypophosphite ion (A)</p> Signup and view all the answers

Sodium thiosulfate is most commonly used for which of the following purposes?

<p>As a stabilizing agent in epinephrine HCl solution (A)</p> Signup and view all the answers

What happens to sodium metabisulfite when exposed to air and moisture?

<p>It oxidizes to sulfate (D)</p> Signup and view all the answers

Which of the following is a synonym for sodium metabisulfite?

<p>Disodium pyrosulfite (D)</p> Signup and view all the answers

What type of odor is associated with sulfur dioxide?

<p>Pungent and suffocating (A)</p> Signup and view all the answers

Flashcards

pH of HCl solution

The pH of a 3.43 x 10⁻⁵ M solution of hydrochloric acid is 4.46.

Hydrogen ion concentration in HCl

A solution of HCl with a pH of 4.52 has a hydrogen ion concentration of 3.02 x 10⁻⁵ M.

Relationship between Ka and pKa

-log Ka = pKa

Relationship between Kw, Ka, Kb

Ka x Kb = Kw = 1 x 10⁻¹⁴. pKa + pKb = pKw = 14.

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Relationship between pH and pOH

pKw = pH + pOH = 14

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Sulfuric Acid Formula

Chemical formula for sulfuric acid is H₂SO₄

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Sulfuric Acid Description

Colorless, odorless liquid, high water affinity, greater than 94% H₂SO₄ and less than 98% H₂SO₄, vaporizes with fumes of SO₂.

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Sulfuric Acid Identity Test (Barium Chloride)

Adding barium chloride to dilute sulfuric acid produces a white precipitate of barium sulfate.

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Sulfuric Acid Identity Test (Lead Acetate)

Dilute sulfuric acid reacts with lead acetate, creating a white precipitate that dissolves in ammonium acetate.

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Sulfuric Acid's Effect on Organics

Sulfuric acid chars or decomposes organic substances like wood, sugar by extracting water, leaving behind carbon.

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Sulfuric Acid Preparation Methods

Sulfuric acid is prepared via lead chamber or catalytic processes, involving sulfur's transformation into sulfur dioxide (SO2).

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Sulfuric Acid Uses

Dehydrating agent (e.g., making Pyroxilin), oxidizing, sulfonating/sulfating agents, creating basic organic drug salts.

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Dilute Sulfuric Acid

A solution of sulfuric acid (H₂SO₄) less than 10% concentration.

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Percent Ionization of a Weak Acid

The percentage of weak acid molecules that are ionized in a solution.

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Percent Ionization of a Weak Base

The percentage of weak base molecules that are ionized in a solution.

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Ionized vs. Nonionized Molecules

Ionized molecules are polar (charged), and nonionized molecules are nonpolar (uncharged). This impacts their ability to cross biological membranes.

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pKa

The negative log of the acid dissociation constant (Ka). It signifies the acidity of the molecule.

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pH

A measure of the hydrogen ion concentration in a solution, determining acidity/alkalinity.

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Weak Acid/Base

An acid/base that doesn't ionize completely in solution.

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Calculating Percent Ionization (Weak Acid)

Using the equation: % ionized = [10^(pH - pKa)] / [1 + 10^(pH - pKa)] * 100.

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Calculating Percent Ionization (Weak Base)

Using the equation: % ionized = 100 / [1 + 10^(pKa - pH)]

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Strong Ammonia Solution

A solution of ammonia (NH3) in water that is highly concentrated, with a high pH value due to its basic nature. It exhibits strong alkaline properties and is widely used in various industries.

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Antioxidant

A substance that inhibits oxidation reactions, which can damage cells and contribute to diseases. Antioxidants protect against free radical damage and are important for health.

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Types of Waters

Categorization of waters based on their mineral content and characteristics. These types include mineral waters, alkaline waters, carbonated waters, and more.

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Official Waters

Waters that meet specific purity standards established by the United States Pharmacopeia (USP). These include Water, USP, Purified Water, USP, Water for Injection, USP, and more.

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Where to find MMSU Pharmacy Department?

The Department of Pharmacy at Mariano Marcos State University (MMSU) is located in the City of Batac, Ilocos Norte, Philippines. They are reachable by phone (63) 77-600-0459 and email [email protected].

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Sodium Bisulfite

A white or yellowish powder with a sulfur dioxide smell. It's used as an antioxidant, for removing stains, and solubilizing certain chemicals.

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Sodium Metabisulfite

White crystals or powder that has an odor of sulfur dioxide and slowly oxidizes to sulfate in air.

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Sodium Thiosulfate

Colorless crystals or granules used as an antidote for cyanide poisoning.

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Hypophosphite Ion

An ion with the formula H2PO2- that acts as a reducing agent.

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How is Sulfur Dioxide prepared?

Burning sulfur or roasting sulfide ores like pyrites, sphalerite, and cinnabar.

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How is Hypophosphite Prepared?

By reacting barium or calcium hypophosphite with sulfuric acid, or by treating sodium hypophosphite with an ion-exchange resin.

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What are the uses of Sodium Bisulfite?

Antioxidant and stabilizing agent, especially in epinephrine HCl solution. Also useful for removing permanganate stains and solubilizing certain dyes and other chemicals. It can also be used topically to treat dermatological problems caused by certain parasites.

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What are the uses of Sulfur Dioxide?

Used as an antioxidant in injectable preparations, bleaching wood pulp, fumigating grains, fumigating houses, and arresting fermentation.

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Sodium Hydroxide Test

A solution of sodium hydroxide (NaOH) diluted 1:25 shows positive results for sodium when tested.

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Sodium Hydroxide Uses

Sodium hydroxide (NaOH) is used as a pH adjuster, to form salts from acids, as an alkalizing agent, in glycerin suppositories, and as a pharmaceutical aid.

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Soda Lime

Soda lime is a mixture of calcium hydroxide (Ca(OH)2) and sodium or potassium hydroxide (NaOH or KOH) used in medical tests and therapies.

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Buffer System

A buffer system is a pair of compounds that resist pH changes when an acid or base is added.

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Buffer Components

Buffers contain a weak acid and its salt (conjugate base) or a weak base and its salt (conjugate acid).

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Buffer pH

The pH of a buffer solution is related to the pKa of the buffer acid and the ratio of the buffering species.

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Pharmaceutical Buffer Selection

Selecting a buffer for pharmaceutical uses involves considering factors like its compatibility with other ingredients, stability, pKa value, pharmacological effects, and microbial growth.

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Causticizing

Causticizing refers to a chemical process involving strong alkali solutions, usually sodium hydroxide, to create a solid product.

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Electrolysis of Brine

Electrolysis of brine (saltwater) using inert electrodes produces sodium hydroxide as a byproduct.

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Nitromersol Solution

Nitromersol Solution uses sodium hydroxide as a pharmaceutical aid to form a water-soluble sodium salt of nitromersol.

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Study Notes

Mariano Marcos State University Rankings

  • QS 4-Star Rating
  • IMPACT RANKINGS 2023, Rank 601-800 in the World
  • Rank 3 among Philippine State Universities and Colleges (SUCs)
  • Green Rank 2 in the Philippines
  • Applied HE™ Public University Ranking: ASEAN 2024, Rank 2 among Philippine SUCs
  • Rank 101st-200th in The World University Rankings for Innovation

Pharmaceutical Aids and Necessities - Unit 8 Objectives

  • Students will recall fundamental concepts of acids, bases, buffers, various types of pharmaceutical waters, and antioxidants.
  • They will calculate pH, pKa, and buffer capacity.

Topic Outline for Unit 8

  • Acids and Bases
  • Buffers
  • Waters
  • Antioxidants

Introduction to Pharmaceutical Aids and Necessities

  • Pharmaceutical aids and necessities are essential substances for preparing, preserving, and storing pharmaceutical products.
  • These substances are typically categorized into official inorganic acids, bases, buffers, antioxidants, various types of water, and glass materials.

Properties of Acids

  • Sour taste
  • Turn blue litmus red
  • Change methyl orange to red
  • Phenolphthalein remains colorless
  • Do not give a soapy touch
  • Give hydrogen ions in solution

Properties of Bases

  • Bitter taste
  • Turn red litmus blue
  • Change methyl orange to yellow
  • Phenolphthalein gives pink color
  • Soapy to touch
  • Give hydroxyl ions in solution

Acid-Base Theories

  • Arrhenius: Produce H+ ions in water; produce OH- ions in water
  • Brønsted-Lowry: Proton donor; proton acceptor
  • Lewis: Electron acceptor; electron donor

Arrhenius Concept

  • Limited to aqueous systems; only considers acids and bases with H+ and OH- ions

Arrhenius Acid Examples

  • HCIO3 (Chloric acid)
  • HNO3 (Nitric acid)
  • HClO4 (Perchloric acid)
  • H3PO4 (Phosphoric acid)
  • H2SO4 (Sulfuric acid)
  • H2SO3 (Sulfurous acid)
  • HCl (Hydrochloric acid)
  • CH3COOH (Acetic acid)
  • HBr (Hydrobromic acid)

Arrhenius Base Examples

  • NaOH (Sodium hydroxide)
  • NH4OH (Ammonium hydroxide)
  • KOH (Potassium hydroxide)
  • Mg(OH)2 (Magnesium hydroxide)
  • Ca(OH)2 (Calcium hydroxide)
  • Al(OH)3 (Aluminum hydroxide)

Examples of Dissociation in Water

  • NaOH (aq) → Na+(aq) + OH-(aq)
  • KOH (aq) → K+(aq) + OH-(aq)
  • Ca(OH)2(aq) → Ca2+(aq) + 2OH-(aq)
  • Mg(OH)2(aq) → Mg2+(aq) + 2OH-(aq)
  • NH4OH(aq) → NH4+(aq)+OH-(aq)

Brønsted-Lowry Concept

  • Acid = proton donor (H+)
  • Base = proton acceptor

Conjugate Acid-Base Pairs

  • Conjugate acid: forms when a base accepts a proton
  • Conjugate base: forms when an acid donates a proton
  • Strong acid → weak conjugate base
  • Strong base → weak conjugate acid

Examples of Brønsted-Lowry Reactions

  • HCl + H2O → H3O+ + Cl-
  • H2O + NH3 → NH4+ + OH-
  • H3PO4 + OH- → H2O + H2PO4-

Dissociation Constants and pH

  • Ka (acid ionization constant): [H3O+][A-]/[HA]
  • Strong acids have large Ka values (Ka > 1)
  • pH = -log [H+]

Hydrogen Ion Concentration and pH

  • pH = -log[H3O+]
  • [H3O+]=antilog-pH

Henderson-Hasselbalch Equation

  • pKa = pH - log [A-]/[HA]
  • pKa = pH + log [HA]/[A-]

Dissociation Constants for Bases and pOH

  • Kb = Keq [H2O] = [BH+] [OH-]/[B]
  • pOH = - log [OH-]
  • pH + pOH = 14

Relationships between Ka, Kb, pH, pOH, and pKw

  • Ka x Kb = Kw = 1 x10-14
  • pKa + pKb = pKw = 14
  • pKw = pH + pOH = 14

Practice Problems & Solutions

  • Various practice problems related to calculations of pH, pOH, Ka, percent ionization, and concentrations of solutions (with provided answers)

Percent lonization for Weak Acids and Bases

  • % ionized = (ionized/[ionized + unionized]) x 100
  • % ionized = [10^(pH - pKa) / (1 + 10^(pH - pKa))] x 100 (for weak acids)
  • % ionized = [1 / (1 + 10^(pKa - pH))] x 100 (for weak bases)

Salts of Acids and Bases - General Properties

  • Weak acids have strong conjugate bases
  • Weak bases have strong conjugate acids
  • Strong acids have weak conjugate bases
  • Strong bases have weak conjugate acids

Inorganic Acids

  • Boric Acid (H3BO3)
  • Hydrochloric Acid (HCl)
  • Nitric Acid (HNO3)
  • Phosphoric Acid (H3PO4)
  • Sulfuric Acid (H2SO4)

Inorganic Bases

  • Strong Ammonia Solution
  • Calcium Hydroxide (Ca(OH)2)
  • Potassium Hydroxide (KOH)
  • Sodium Carbonate (Na2CO3)
  • Sodium Hydroxide (NaOH)

Antioxidants

  • Hypophosphorous Acid (H3PO2)
  • Sodium Bisulfite
  • Sodium Metabisulfite
  • Sulfur Dioxide (SO2)
  • Sodium Thiosulfate (Na2S2O3)
  • Sodium Nitrite (NaNO2)
  • Nitrogen (N2)

Official Waters

  • Water, USP
  • Purified Water, USP
  • Water for Injection, USP
  • Bacteriostatic Water for Injection, USP
  • Sterile Water for Injection, USP

Pharmaceutical Glass Types

  • Type I
  • Type II
  • Type III
  • Type NP
  • Buffer Solutions and their properties
  • Henderson-Hasselbalch Equation
  • Buffer Selection in Pharmaceutical Preparations

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Unit 8: Pharmaceutical Aids and Necessities (PDF)

Description

Test your knowledge on pH calculations, relationships between pKa and pKb, and the properties of different types of aqueous solutions. This quiz covers essential concepts related to acids, pH, and their biological implications. Perfect for students studying chemistry or related fields.

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