Review the key concepts, formulae, and examples before starting your quiz.
🔑Concepts
Acids are substances that have a pH value of less than 7. They release hydrogen ions () when dissolved in water.
Alkalis are bases that are soluble in water. They have a pH value greater than 7 and release hydroxide ions () in solution.
The pH scale ranges from 0 to 14. A pH of 7 is considered neutral, such as pure water ().
Indicators are substances that change color depending on whether they are in an acidic or alkaline solution. Examples include Litmus (Red in acid, Blue in alkali) and Universal Indicator.
Neutralization is a chemical reaction where an acid and an alkali react to form a salt and water. The general word equation is: .
Common laboratory acids include Hydrochloric acid (), Sulfuric acid (), and Nitric acid ().
Common laboratory alkalis include Sodium hydroxide (), Potassium hydroxide (), and Calcium hydroxide ().
📐Formulae
(Ionic equation for neutralization)
💡Examples
Problem 1:
If a solution has a pH of 3, what color will it turn Universal Indicator, and is it a strong or weak acid?
Solution:
Orange/Red; it is a relatively strong acid.
Explanation:
On the pH scale, values from 0-3 are typically considered strong acids and appear red or orange with Universal Indicator.
Problem 2:
Complete the chemical equation for the reaction between Sulfuric acid () and Sodium hydroxide ().
Solution:
Explanation:
Sulfuric acid reacts with Sodium hydroxide to produce Sodium sulfate (the salt) and water. We need 2 molecules of to balance the sulfate group and the hydrogen atoms.
Problem 3:
What is the name of the salt produced when Hydrochloric acid () reacts with Potassium hydroxide ()?
Solution:
Potassium chloride ()
Explanation:
In a neutralization reaction, the salt's name comes from the metal in the alkali (Potassium) and the non-metal part of the acid (Chloride from Hydrochloric acid).