ch5 everything Flashcards
(21 cards)
Q: What is the Arrhenius definition of an acid and a base?
A: An acid contains a hydrogen atom and dissolves in water to form a hydrogen ion (H+). A base contains hydroxide and dissolves in water to form OH−.
Q: Why is the Arrhenius definition limited?
A: The Arrhenius definition is limited because it does not account for the fact that H+ does not exist in water; instead, it forms the hydronium ion (H3O+).
Q: What is the Brønsted–Lowry definition of an acid and a base?
A: A Brønsted–Lowry acid is a proton (H+) donor, and a Brønsted–Lowry base is a proton (H+) acceptor.
Q: What must a Brønsted–Lowry acid contain?
A: A Brønsted–Lowry acid must contain a hydrogen atom.
Q: How are the names of common acids derived?
A: The names of common acids are derived from the anions formed when they dissolve in water. For example, chloride (Cl−) becomes hydrochloric acid (HCl).
Q: What are monoprotic, diprotic, and triprotic acids?
A: A monoprotic acid contains one acidic proton (e.g., HCl), a diprotic acid contains two acidic protons (e.g., H2SO4), and a triprotic acid contains three acidic protons (e.g., H3PO4)
Q: What is required for a Brønsted–Lowry base to accept a proton?
A: A Brønsted–Lowry base must contain a lone pair of electrons to form a bond with the proton.
Q: What are some common Brønsted–Lowry bases?
A: Common Brønsted–Lowry bases include NaOH (sodium hydroxide), KOH (potassium hydroxide), Mg(OH)2 (magnesium hydroxide), Ca(OH)2 (calcium hydroxide), H2O (water), and NH3 (ammonia).
Q: What is a conjugate base and a conjugate acid?
A: The product formed by the loss of a proton from an acid is called its conjugate base, and the product formed by the gain of a proton by a base is called its conjugate acid.
Q: What is an amphoteric compound?
A: An amphoteric compound contains both a hydrogen atom and a lone pair of electrons, allowing it to act as either an acid or a base
Q: What is dissociation in the context of acids and bases?
A: Dissociation is the splitting apart of a covalent molecule or ionic compound into its ions.
Q: What is the difference between strong and weak acids?
A: A strong acid completely dissociates into ions in water, while a weak acid only partially dissociates.
Q: What is the difference between strong and weak bases?
A: A strong base completely dissociates into ions in water, while a weak base only partially dissociates.
Q: How does the strength of an acid or base relate to its conjugate?
A: A strong acid forms a weak conjugate base, and a strong base forms a weak conjugate acid.
Q: What is the ion-product constant for water (Kw)?
A: Kw is the product of the concentrations of H3O+ and OH− ions in water, and it is equal to 1.0 x 10^-14 at 25°C.
Q: How do you calculate the concentration of OH− when the concentration of H3O+ is known?
A: Use the formula Kw = [H3O+][OH−]. For example, if [H3O+] = 1.0 x 10^-5 M, then [OH−] = Kw / [H3O+] = 1.0 x 10^-14 / 1.0 x 10^-5 = 1.0 x 10^-9 M.
Q: What is the pH scale and how is it related to the concentration of H3O+?
A: The pH scale measures the acidity or basicity of a solution. A lower pH indicates a higher concentration of H3O+. Acidic solutions have pH < 7, basic solutions have pH > 7, and neutral solutions have pH = 7.
Q: What is a neutralization reaction?
A: A neutralization reaction is an acid-base reaction that produces a salt and water as products.
Example: Write a balanced equation for the reaction of Mg(OH)2 with HCl.
Question: How do you draw a balanced equation for a neutralization reaction?
Answer:
Identify the acid and base in the reactants and draw H2O as one product: HCl(aq) + Mg(OH)2(aq) → H2O(l) + MgCl2(aq)
Determine the structure of the salt: Mg2+ and Cl− combine to form MgCl2.
Balance the equation: HCl(aq) + Mg(OH)2(aq) → 2H2O(l) + MgCl2(aq)
Q: What is titration and what is its purpose?
A: Titration is a method used to determine the concentration of an acid or base in a solution by adding a base or acid of known concentration until neutralization occurs.
Flashcard 21
Example: What is the molarity of an HCl solution if 22.5 mL of a 0.100 M NaOH solution are needed to titrate a 25.0 mL sample of the acid?
Question: How do you determine the molarity of an acid solution from titration data?
Answer:
Determine the number of moles of base used to neutralize the acid: 22.5 mL NaOH x (1 L / 1000 mL) x (0.100 mol NaOH / 1 L) = 0.00225 mol NaOH
Determine the number of moles of acid that react from the balanced chemical equation: HCl + NaOH → H2O + NaCl 0.00225 mol NaOH x (1 mol HCl / 1 mol NaOH) = 0.00225 mol HCl
Determine the molarity of the acid from the number of moles and the known volume: M = mol / L = 0.00225 mol HCl / 0.025 L = 0.0900 M HCl
