chem
to find the pH value you should know ________ concentration
H+
the lower the pH the _______________ H+ concentration
higher
a strong acid ____________ ionizes
completely
the higher the Ka __________________
the stronger the acid
the equivalence point on titration curve of a weak acid and strong base is
above 7
NaOH + HCl -->
NaCl + H2O
a buffer is ____________
a substance that resist the pH change when small amount of acid or base is added
Calculate the pH of a solution with a hydrogen ion concentration of 1 x 10-3
pH = 3
If the pH of a solution is 5, what is the concentration of H+ ions?
[H+] = 1 x 10-5 M.
How does the pH of a strong acid compare to that of a weak acid at the same concentration? explain
A strong acid will have a lower pH.
as it completely ionizes more H+ ions will be there the higher the H+ concentration, the lower the pH
Why is HF considered a weak acid despite being a halide acid?
HF does not completely dissociate in water.
What is the role of an indicator in titration?
To show a visible change, like a color change, at or near the end point
How does a buffer work?
It works by neutralizing added H+ or OH- through a weak acid and its conjugate base, or a weak base and its conjugate acid.
How can you differentiate between acidic, basic, and neutral salts?
Acidic salts come from a strong acid and weak base, basic salts from a weak acid and strong base, and neutral salts from a strong acid and strong base.
why the concentration do not affect the strength of the acid?
it depends on ionization but not concentration
A 0.1 M solution of a weak acid has a pH of 3. What is the Ka of the acid?
1x10-5
During a titration, the pH at the equivalence point is 8.7. What does this suggest about the acid and base involved?
It suggests the acid is weak and the base is strong, as the pH is slightly basic at the equivalence point.
a buffer made of CH3COOH and its conjugate base CH3COO- if we add a small amount of HCl how would the buffer resist change in pH?
The HCl will be neutralized by the acetate ions (CH3COO-), preventing a large pH drop.
Why does the neutralization of a weak acid with a strong base result in a basic solution?
Since the weak acid does not fully donate its protons, and the strong base generates an excess of hydroxide ions, the end solution has a higher concentration of hydroxide ions than hydrogen ions (H+), resulting in a basic solution but not strongly basic, as most of the strong base's hydroxide ions are neutralized.
Explain why increasing the concentration of a strong acid in a buffered solution has a smaller effect on pH than in a non-buffered solution
The buffer neutralizes some of the added H+, resisting large changes in pH, whereas a non-buffered solution has no mechanism to prevent pH changes.
Why is the pH of blood maintained within a narrow range, and how do buffer systems in the body help achieve this?
The pH of blood must remain between 7.35 and 7.45 for proper physiological function. Buffer systems like the bicarbonate buffer prevent drastic changes in pH by neutralizing excess acids or bases.
Calculate the volume of 0.1 M NaOH needed to titrate 25 mL of 0.05 M H2SO4 to the first equivalence point.
Vb=25 mL
Compare and contrast strong acids and weak acids in terms of dissociation, pH, and electrical conductivity. Provide examples of both.
Strong acids dissociate completely in water, meaning nearly all of their molecules release H⁺ ions. Examples include HCl, HNO₃, and H₂SO₄. Weak acids only partially dissociate in water, so not all of their molecules release H⁺ ions. Examples include acetic acid (CH₃COOH) and citric acid.
why can't a strong acid be a buffer?
Complete Ionization: Strong acids, like hydrochloric acid (HCl), dissociate completely in water, meaning they do not exist in equilibrium between their ionized and unionized forms. Buffers rely on the presence of both an acid and its conjugate base in equilibrium to neutralize added acids or bases. Since strong acids ionize completely, no substantial amount of the acid remains in its non-ionized form to establish this equilibrium.
when a wasp sting a person adding vinegar on the sting area decrease the pain ?
A wasp sting, on the other hand, is mildly basic, so a household remedy for this will be vinegar, also known as acetic acid. These simple treatments ease these painful stings by a process called neutralization.