Acids And Bases Flashcards
what is the pH scale
a measure of how acidic or alkaline a solution is
what does a pH of 7 indicate
a neutral substance
what is an acid
a substance with a pH less than 7
what do acids form in water
hydrogen ions
what does a higher concentration of hydrogen ions in a solution result in
- the solution becoming more acidic
- so the lower pH it will be
what is a base
a substance that reacts with an acid to produce salt and water
what is an alkali
a base that is soluble in water
what do all alkalis have and form
- a pH of more than 7
- they form OH- ions (hydroxide ions) in water
what does a higher concentration of OH- ions indicate
a higher pH
what is an indicator
- a dye that changes colour
- depending on whether it is above or below a certain pH
what chart is most commonly used to work out the acidity or alkaline nature of a substance
the pH chart for universal indicator
what are the three most commonly used indicators
- litmus
- methyl orange
- phenolphthalein
how does litmus indicate the pH of a substance
- its red in acidic solutions
- purple in neutral solutions
- blue in alkaline solutions
how does methyl orange indicate the pH of a substance
- its red in acidic solutions
- yellow in neutral and alkaline solutions
how does phenolphthalein indicate the pH of a substance
- its colourless in acidic or neutral solutions
- turns pink in alkaline solutions
