Acids and Alkalis Flashcards
What does a pH below 7 indicate?
An Acid.
What does a pH above 7 indicate?
An Alkali.
What does a pH of 7 indicate?
A Neutral solution.
What colour will an indicator turn when put into an Acid?
Red/Orange.
What colour will an indicator turn when put into an Alkali?
Blue/Purple.
What colour will an indicator turn when put into a Neutral Solution?
Green.
Why do Acidic Solutions have a pH of less than 7?
They contain more hydrogen ions (H+) than hydroxide ions (OH-)
H+>OH-
Can Acids conduct electricity?
Yes, as they contain ions that are free to move.
What happens when Acids are dissolved in water?
The concentration of H+ ions decreases, increasing the pH towards 7.
The conductivity of the acid will decrease.
What forms acidic solutions?
Soluble Non-Metal Oxides form acidic solutions.
Why do alkaline solutions have a pH above 7?
They contain a greater concentration of hydroxide ions (OH-) than Hydrogen ions (H+).
OH->H+
Can Alkaline solutions conduct electricity?
Yes, as they have ions that are free to move.
What happens when an Alkaline solution is diluted?
The concentration of OH- ions decreases, decreasing the pH towards 7.
The conductivity of will decrease.
What forms Alkaline solutions?
Soluble Metal Oxides.
Why do Neutral solutions have a pH of 7.
A Neutral solution has an equal concentration of H+ and OH- ions. Therefore they cancel each other out.
Water is a reversible reaction. Why is this?
Very small proportions of the water molecules will naturally dissociate to form an equal number of hydrogen and hydroxide ions.
What is a Neutralisation Reaction?
Neutralisation is the reaction between acids and a base. This will move the pH of the acid up towards 7 and the base down towards 7.
What are three examples of Bases?
Metal Oxides
Metal Hydroxides
Metal Carbonates.
Can insoluble Bases still neutralise acids?
Yes, but would not form an alkaline solution.
When acids are neutralised, what is formed?
Salt and Water. (And Carbon Dioxide if the base is a Metal Carbonate)
What is a Spectator ion?
Spectator ions are ions which are unchanged by a chemical reactions and remain the same on both sides.
What are the steps to solving a Spectator Ion question?
- Word Equation
- Formula
- Ionic Formula
- Removing Spectators.
Why would you use an acid/base Titration?
To determine the concentration of an acid/base.
What is a Pipette?
A pipette is used to accurately measure the volume of a standard solution.
What is a Standard Solution?
A standard solution is a solution of accurately known concentration.
What is a Burette?
The burette contains the acid/base of accurately known concentration.
Which indicator is used to determine the point of neutralisation?
Phenolphthalein.
Base containing indicator (Pink/Purple) + Acid = Clear
Errors of titrations and solutions?
Burette too high/far away from the conical flask (splashes/lost solution) - Bring burette down/closer to conical flask.
Burette too high to read - Bring down to eye level.
What is a Concordant Value?
Concordant values need to be within 0.2 cm3 of each other.
What is the method of Titration calculations?
- Establish the molar ratio using the balanced equations.
- Calculate the number of moles.
- Use molar ratio.
- Finish off calculating the concentration.
