What does the pH scale measure?
The acidity or alkalinity of a substance
What is the number range of the pH scale?
What is the colour range for the pH scale?
What is the pH range for acids?
Less than 7
Do strong acids have a higher or lower pH than weak acids?
What is the pH range for alkalis?
Greater than 7
Do strong alkalis have a higher or lower pH than weak alkalis?
What is the pH value for neutral solutions?
True or false? The pH scale can only measure in whole numbers.
What is an indicator?
A substance that changes colour to identify pH values
How do we test a substance for pH using universal indicator?
1. Substance must be in aqueous solution
2. Place a few drops of indicator solution into a small volume of the substance.
3. Compare and match the colour to appropriate colour chart
4. Read off correct pH value for that colour
What are some natural sources of indicators?
Plants, fruits and flowers
How do you make red cabbage indicator?
What is the colour scale for red cabbage indicator?
Name 3 indicators used in the lab
pH paper universal indicator red cabbage indicator
What happens when we dilute a substance using water?
The number of particles per ml decreases
What particle makes solutions acidic?
The H particle
What particle makes solutions alkaline
The OH particle
What is concentration?
What happens to the pH of acids when we dilute them with water?
The pH increases towards 7
What happens to the pH of alkalis when we duilute them?
The pH decreases towards 7
How does diluting an acid increase pH?
The concentration of acidic (H) particles decreases.
By what factor do we have to dilute acids to increase the pH by approx 1?
By a factor of 10
What is meant by neutralising an acid?
Bringing the pH up to 7
What are the products of neutralising acids with alkalis?
How can we separate the 2 products?
What is an advantage of using phenolphthalein indicator when neutralising?
Immediate colour change when neutral
What gas is produced when metals react with acids?
The hydrogen particles in the acid turn into hydrogen gas
How can we compare the reactivity of metals by placing them in acid?
What is the test for hydrogen?
Burns with a "pop"