Solutions, Acids and Bases Flashcards
What is an Arrhenius acid?
An Arrhenius acid is a substance whose aqueous solution contains hydrogen ion (H+) or hydronium ion (H3O+) as the only positive ion in solution.
HCl is an example of an acid. Other common acids are listed in Table K.
What is an Arrhenius base?
An Arrhenius base is a substance that produces hydroxide ions (OH–) as the only negative ion in aqueous solution.
NaOH is an example of a base. Other common bases are listed in Table L.
What is an electrolyte?
An electrolyte is a substance that will dissolve in water to form a solution that will conduct an electric current.
The ability of a solution to conduct an electric current is due to the presence of mobile ions. Solutions of acids, bases, and salts will conduct electricity.
What is an acid-base indicator?
An acid-base indicator is a substance whose color changes when placed in an acidic or basic solution.
Litmus and phenolphthalein are examples of indicators. Other indicators are listed in Table M.
What are the characteristics of an acid?
- Acids have a pH less than 7.
- Acids will react with active metals to produce hydrogen gas.
- Dilute acid solutions have a sour taste.
- Acid solutions conduct electricity.
- Acids cause color changes in acid-base indicators.
- Acids neutralize bases to form water and a salt.
What are the characteristics of a base?
- Bases have a pH greater than 7.
- Bases have a bitter taste.
- Dilute base solutions have a slippery or soapy feel.
- Bases cause acid-base indicators to change color.
- Bases react with acids to form water and a salt.
- Aqueous solutions of bases conduct electricity.
What is molarity?
Molarity is a measure of the concentration of a solution expressed as the number of moles of solute contained in a liter of solution.
What is the pH of a neutral solution?
A neutral solution has a pH of 7.
In a neutral solution the concentration of H+ ions is equal to the concentration of OH– ions.
What are the safe methods of determining whether a solution contains an acid or a base?
- Check the pH of the solution with a pH meter. Acidic solutions will have a pH less than 7; basic solutions will have a pH greater than 7.
- Add an active metal to the solution. Acids will react with the metal to produce H2 gas; bases will not react with the metal.
- Test the solution with an acid-base indicator. The best indicators to use for this are either litmus or bromthymol blue.
What does pH measure?
pH measures the concentration of hydrogen ions in solution.
pH = –log[H+]
What is a neutralization reaction?
A neutralization reaction occurs when an acid and base react to produce a salt and water.
The reaction below is an example of a neutralization reaction:
HCl + NaOH → NaOH + H2O
What is the color of litmus in a neutral solution?
Litmus is purple in a neutral (ph = 7) solution.
What is the end point in a titration?
The end point is the point in a titration when the indicator changes color.
Ideally, the indicator is chosen so that the end point occurs at near the point when the moles of acid are equal to the moles of base (the acid and the base completely neutralize each other).
What is the pH of a solution that has a hydrogen ion concentration of 1 x 10–5?
pH = 5.
pH = – log [H+] = – log (1 x 10–5)
The pH of a lake is 7. An acid spill causes the hydronium ion concentration to increase by 1000. What is the new pH of the lake?
The new pH is 4.
A decrease in one unit of pH is equivalent to a ten-fold increase in the hydronium ion concentration.
