Acids and Bases Flashcards
Chemical Changes (19 cards)
What does the pH scale measure?
The pH scale measures how acidic or alkaline a solution is.
The scale ranges from 0 to 14.
What does a lower pH indicate about a solution?
The lower the pH, the more acidic the solution is.
What pH value represents a neutral substance?
pH 7 represents a neutral substance, such as pure water.
What is an acid?
An acid is a substance that forms aqueous solutions with a pH of less than 7.
What ions do acids form in water?
Acids form H+ ions in water.
What is a base?
A base is a substance with a pH greater than 7.
What is an alkali?
An alkali is a base that dissolves in water to form a solution with a pH greater than 7.
What ions do alkalis form in water?
Alkalis form OH- ions in water.
What is the reaction between acids and bases called?
The reaction is called neutralisation.
What is the general equation for neutralisation?
acid + base → salt + water.
What happens to the pH when an acid neutralises a base?
The products are neutral, having a pH of 7.
What is an indicator?
An indicator is a dye that changes color depending on whether the pH is above or below a certain value.
What is a wide range indicator?
A wide range indicator is a mixture of dyes that gradually change color over a broad range of pH.
How can pH be measured electronically?
Using a pH probe attached to a pH meter.
What does the pH meter display?
The pH meter displays the pH value as a numerical value.
What is produced when H+ ions react with OH- ions?
Water (H2O) is produced.
Fill in the blank: An acid forms _______ ions in water.
H+.
Fill in the blank: An alkali forms _______ ions in water.
OH-.
True or False: All neutralisation reactions result in products with a pH of 14.
False.
