Strong Acids and Weak Acids Flashcards
How does acids ionise in an aqueous solution? Give examples.
The acids produce hydrogen ions, H+.
HCI → H+ + Cl-.
HNO₃ → H+ + NO₃
What are strong acids?
Stong acids (e.g. sulfuric, hydrochloric and ntric acids) ionise completely in water. All acid particles dissociate to realease H+ ions.
What are weak acids?
Weak acids (e.g. ehanoic, citric and carbonic acids) do not fully ionise in solutiion. Only a small proportion of acid particles dissociate to release H+ ions.
What sets up an equilibrium between the undissociated and associated acid?
The ionisation of a weak acid is a reversible reaction, which sets up an equilibrium between the undissociated and dissociated acid. Since only a few of the acid particles release H+ ions, the positium of equilibrium lies well to the left.
What the reation of acids involve the H+ ions react with? Explain it.
Reactions of acids involve the H+ ions reacting with other substances. If the concentration of H+ ions are higher, the rate of reaction will be faster, so strong acids will be more reactive than weak acids of the same concentration.
What is the pH of an acid or alkali is measuring?
The pH of an acid or alkali is a measure of th concentration of H+ ions in the solution.
How much is every decrease of 1 on the pH scale in the concentration of H+ ions? Explain it.
For every decrease of 1 on the pH scale, the concentration of H+ ions increases by a factor f 10. So, an acid that has a pH of 4 has 10 times the concetration of H+ ions of an acid that has a pH of 5. For a decrease of 2 on the pH scale, the concentration of H+ ions increases by a factor of 100.
What does “X” stands for?
Factor H+ ion concentration changes by = 10^-X.
X is the difference in pH. So if pH falls from 7 to 4 the difference is -3, and the factor the H+ ion concentration has increased by is 10^-(-3) = 10^3.
