Chemical Changes Flashcards
What is the pH scale?
Scale from 0-14. Measures how acidic/alkaline a solution is.
What is the pH of a neutral substance?
pH 7.
What is the pH of an acidic substance and what do acidic solutions form in water?
pH -7. Form H+ ions (hydrogen ions).
As concentration of H+ ions increases…
pH decreases. Essentially getting +acidic and stronger but the number is lower.
What is a base?
A substance that reacts with an acid to produce (a) salt and water.
What is an alkali and what is its pH?
A base that’s soluble in water. pH +7.
What do alkalis form in water?
Form OH- ions in water.
The higher the concentration of OH- ions, the…
Higher the pH.
What is an indicator?
A dye that changes colour depending whether it’s above/below certain pH.
How do you use an indicator?
Add few drops to solution, compare colour solution goes, to pH chart for that indicator.
What is litmus?
An indicator.
It’s red in acidic conditions,
purple in neutral,
and blue in alkaline.
What is Methyl orange?
An indicator.
It’s red in acidic conditions,
yellow neutral + alkali.
What is phenolphthalein?
An indicator.
Colourless acidic + neutral,
pink alkaline.
What is the reaction between an acidic and a base called?
Neutralisation (reaction).
What does the reaction between an acid and base produce?
Salt and water (base is a substance that reacts with acid to produce salt and water).
