CHEM311 Chapter 2: Water and Polarity

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What is the purpose of using buffers in a solution?

To maintain a stable pH by neutralizing small quantities of additional acid or base (correct)

To make the solution more acidic

To decrease the pH of the solution

To neutralize large quantities of acids or bases

In a buffer solution, which component neutralizes a strong base?

The spectator ion

The strong acid

The acid (correct)

The conjugate base

What is a common buffering agent with a pKa value of 6.40?

Citric acid

Acetic acid

KH2PO4 (correct)

Borate

In a phosphate buffer system, what is the typical useful pH range?

6.2 to 8.2 Signup and view all the answers

What is the general rule regarding the effective range of a buffer in relation to its pKa value?

The effective range is +/- 1 pH unit of the pKa value of the weak acid Signup and view all the answers

What is a key criterion for selecting a buffer?

Matching pKa value with the system Signup and view all the answers

Which of the following is NOT a typical criterion for selecting a buffer?

High solubility Signup and view all the answers

What is the principal buffer in cells?

$H_2PO_4^-/HPO_4^{2-}$ Signup and view all the answers

What happens to blood pH if someone hyperventilates?

It increases Signup and view all the answers

If the buffering capacity of a solution is very high, what does that indicate about the concentrations of the weak acid and its conjugate base?

High concentrations Signup and view all the answers

What is the pH of a solution after adding 1.5mL of 2.0M HCl to 10.0mL of water?

5.58 Signup and view all the answers

If you add 1.5mL of 2.0M HCl to a buffer solution, what will happen to the buffer's pH?

It will decrease Signup and view all the answers

In a mixture of 0.55M carbonic acid and 0.55M sodium hydrogen carbonate, what is the resulting pH when 1.5mL of 2.0M HCl is added?

5.84 Signup and view all the answers

How does the addition of HCl impact the concentration of carbonic acid in the mixture of carbonic acid and sodium hydrogen carbonate?

Increases Signup and view all the answers

What is the significance of maintaining a specific buffer ratio in a buffer system?

To neutralize any added acid or base Signup and view all the answers

What happens when the concentrations of a weak acid and its conjugate base are equal in a solution according to the Henderson-Hasselbalch equation?

The pH of the solution equals the pKa of the weak acid Signup and view all the answers

Which type of buffer contains a weak acid and its salt or a weak base and its salt?

Buffer resistant to pH change Signup and view all the answers

How do buffers work when a strong base is added to a buffer solution?

The weak acid absorbs the H+ to neutralize the base Signup and view all the answers

What happens when a strong acid is added to a buffer solution?

The pH changes only slightly Signup and view all the answers

What characterizes a buffer's resistance to changes in pH?

The ability of the buffer to absorb or release H+ ions without significant changes in pH Signup and view all the answers

What is the role of a weak acid in an aqueous solution?

Exists as a conjugate acid-base pair Signup and view all the answers

How is the strength of an acid described?

Quantified by Ka value Signup and view all the answers

Which concept connects the equilibrium constant (K) to the pH of a solution containing both an acid and a base?

Henderson-Hasselbalch equation Signup and view all the answers

What is the ionization constant for water at 25°C?

[H+] * [OH-] = 10^-7 Signup and view all the answers

What is the molar concentration of water used to calculate the ionization constant for water at 25°C?

55.5 M Signup and view all the answers

What determines the polarity of a molecule?

The geometry of the molecule and the polarity of the bonds Signup and view all the answers

What type of bonds are polar covalent bonds?

Bonds where electrons are shared but not equally Signup and view all the answers

What is electronegativity in relation to a compound?

The ability of an atom in a compound to draw electrons to itself Signup and view all the answers

How does the geometry of a molecule affect its polarity?

It can determine whether the molecule is polar or nonpolar Signup and view all the answers

What does a polar covalent bond imply about electron sharing?

Electrons are shared but not equally between atoms Signup and view all the answers

Which type of molecules tend to dissolve in water?

Hydrophilic Signup and view all the answers

What type of interactions are very weak between nonpolar molecules?

Van der Waals interactions Signup and view all the answers

What kind of molecules have characteristics of both hydrophobic and hydrophilic regions?

Amphipathic molecules Signup and view all the answers

What is the term for a spherical arrangement of organic molecules in water solution?

Micelle Signup and view all the answers

Which type of bonds are responsible for the attraction between temporary induced dipoles in micelle formation?

Van der Waals interactions Signup and view all the answers

What does a Brønsted-Lowry acid donate?

Proton (hydrogen ion) Signup and view all the answers

In the context of acids and bases, what does a Brønsted-Lowry base accept?

Proton (hydrogen ion) Signup and view all the answers

What is the term for molecules that contain one or more hydrophobic and one or more hydrophilic regions?

Amphipathic molecules Signup and view all the answers

What is the main type of bond responsible for forming hydrophobic interactions?

Van der Waals interactions Signup and view all the answers

What is the key characteristic of micelles in aqueous solutions?

Hydrophobic parts on the surface of the sphere Signup and view all the answers

CHEM311 Chapter 2: Water and Polarity

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Questions and Answers

What is the purpose of using buffers in a solution?

In a buffer solution, which component neutralizes a strong base?

What is a common buffering agent with a pKa value of 6.40?

In a phosphate buffer system, what is the typical useful pH range?

What is the general rule regarding the effective range of a buffer in relation to its pKa value?

What is a key criterion for selecting a buffer?

Which of the following is NOT a typical criterion for selecting a buffer?

What is the principal buffer in cells?

What happens to blood pH if someone hyperventilates?

If the buffering capacity of a solution is very high, what does that indicate about the concentrations of the weak acid and its conjugate base?

What is the pH of a solution after adding 1.5mL of 2.0M HCl to 10.0mL of water?

If you add 1.5mL of 2.0M HCl to a buffer solution, what will happen to the buffer's pH?

In a mixture of 0.55M carbonic acid and 0.55M sodium hydrogen carbonate, what is the resulting pH when 1.5mL of 2.0M HCl is added?

How does the addition of HCl impact the concentration of carbonic acid in the mixture of carbonic acid and sodium hydrogen carbonate?

What is the significance of maintaining a specific buffer ratio in a buffer system?

What happens when the concentrations of a weak acid and its conjugate base are equal in a solution according to the Henderson-Hasselbalch equation?

Which type of buffer contains a weak acid and its salt or a weak base and its salt?

How do buffers work when a strong base is added to a buffer solution?

What happens when a strong acid is added to a buffer solution?

What characterizes a buffer's resistance to changes in pH?

What is the role of a weak acid in an aqueous solution?

How is the strength of an acid described?

Which concept connects the equilibrium constant (K) to the pH of a solution containing both an acid and a base?

What is the ionization constant for water at 25°C?

What is the molar concentration of water used to calculate the ionization constant for water at 25°C?

What determines the polarity of a molecule?

What type of bonds are polar covalent bonds?

What is electronegativity in relation to a compound?

How does the geometry of a molecule affect its polarity?

What does a polar covalent bond imply about electron sharing?

Which type of molecules tend to dissolve in water?

What type of interactions are very weak between nonpolar molecules?

What kind of molecules have characteristics of both hydrophobic and hydrophilic regions?

What is the term for a spherical arrangement of organic molecules in water solution?

Which type of bonds are responsible for the attraction between temporary induced dipoles in micelle formation?

What does a Brønsted-Lowry acid donate?

In the context of acids and bases, what does a Brønsted-Lowry base accept?

What is the term for molecules that contain one or more hydrophobic and one or more hydrophilic regions?

What is the main type of bond responsible for forming hydrophobic interactions?

What is the key characteristic of micelles in aqueous solutions?

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