7.1 - characteristics & properties of acids and bases Flashcards
What colour does red litmus paper turn in acidic solutions? [1]
stays red
What colour does red litmus paper turn in alkaline solutions? [1]
turns blue
What colour does universal indicator turn in acidic solutions? [1]
changes to red
What colour does blue litmus paper turn in acidic solutions? [1]
turns red
What colour does blue litmus paper turn in alkaline solutions? [1]
stays blue
What colour does methyl orange turn in alkaline solutions? [1]
changes to yellow
What colour does methyl orange turn in acidic solutions? [1]
changes to red
What colour does phenolphthalein turn in acidic solutions? [1]
colourless / no change
What colour does universal indicator turn in alkaline solutions? [1]
changes to blue
What colour does phenolphthalein turn in alkaline solutions? [1]
changed to pink
What type of bond is expected in acids and why? [2]
- covalent bond
- because all acids contain non-metals
What type of bond is expected in alkalis and why? [2]
- ionic
- because all alkalines contain a metal
What is an ionic bond? [2]
the transfer of electrons between positive and negative ions
What is the difference between a base and an alkali? [2]
alkaline is a base that is soluble in water
What are acids? [2]
- proton donors
- H+ hydrogen ion donors
What is a covalent bond? [2]
shared pair of electrons between two non-metals
What is a solute? [1]
the solid that dissolves in the solvent
What does concentrated mean? [1]
greater amount in the same volume
What are alkalis? [2]
- proton acceptors
- H+ hydrogen ion acceptor
What does dilute mean? [1]
small amount of substance in a large amount of liquid
What is a strong acid? [1]
almost all molecules are dissociated
What is a weak acid? [1]
only some of the molecules have been dissociated
What is an alkali the source of? [1]
source of hydroxide ion (OH-)
What is a solvent? [1]
the liquid a solute dissolves in
Name some common acids [3]
- hydrochloric acid
- sulphuric acid
- citric acid
What is a solution? [1]
the mixture of a solute and the solvent
What happens to the pH when the concentration of the hydroxide ion is low? [1]
the lower the pH
What is the pH for acidic substances? [1]
<7
Name some common alkalis [3]
- sodium hydroxide
- potassium hydroxide
- iron hydroxide
What happens to the pH when the concentration of the hydrogen ion is high? [1]
the lower the pH
What happens to the pH when the concentration of the hydrogen ion is low? [1]
the higher the pH
What happens to the pH when the concentration of the hydroxide ion is high? [1]
the higher the pH
How many cm3 in 1dm3? [2]
1000cm3 = 1dm3
What is the range of the pH scale? [2]
0-14
What is the pH for alkaline substances? [1]
> 7
What is the neutral pH? [1]
pH 7
Why do we need to control acidity in soil? [2]
- need to increase the pH
- for crop/plant growing
How do we control the acidity in soil? [3]
- neutralise it
- neutralise it with a base
- e.g. metal oxide, carbonate or hydroxide
