Acids, bases and salts Flashcards
Describe Alkaline in terms of pH
had a pH above 7
Describe acid in terms of pH
has pH below 7
Describe neutral in terms of pH
Neither acidic nor alkaline; neutral solutions have a pH of 7
Acid + alkali –>
Salt + water
Acid + metal
Salt + hydrogen
Acid + Carbonate
Salt + Water + Carbon dioxide
Acid + Oxide (bases)
Salt + Water
characteristic properties of bases
- Have a pH above 7
- A base which is water-soluble is referred to as an alkali
- Turns red litmus paper blue
What is the test for a carbonate? (tests to identify anions)
Add dilute acid
Effervescence, carbon dioxide produced
What is the test for chloride (in solution)? (tests to identify anions)
Acidify with dilute nitric acid, then add
aqueous silver nitrate
Test results: white ppt
What is the test for bromide (in solutions? (test for anions)
acidify with dilute nitric acid, then add
aqueous silver nitrate
Test result: cream ppt
What is the test for nitrate (in solution)? (test for anions)
add aqueous sodium hydroxide, then
aluminium foil; warm carefully
Test result: ammonia produced
What is the test for sulphate (in solution)? (test for anions)
acidify, then add aqueous barium nitrate
Test result: white ppt
What is the test for ammonium? (test for aqueous cations)
effect of aqueous sodium hydroxide: Ammonia produced on warming
What is the test for calcium? (test for aqueous cations)
effect of aqueous sodium hydroxide: white ppt., insoluble in excess
effect of aqueous ammonia: no ppt. or very slight white ppt.
What is the test for copper (II)? (test for aqueous cations)
effect of aqueous sodium hydroxide: light blue ppt., insoluble in excess
effect of aqueous ammonia: light blue ppt., soluble in excess, giving a dark blue solution
What is the test for iron (II)? (test for aqueous cations)
effect of aqueous sodium hydroxide: green ppt., insoluble in excess
effect of aqueous ammonia: green ppt., insoluble in excess
What is the test for iron (III)? (test for aqueous cations)
effect of aqueous sodium hydroxide: red-brown ppt., insoluble in excess
effect of aqueous ammonia: red-brown ppt., insoluble in excess
What is the test for Zinc? (test for aqueous cations)
effect of aqueous sodium hydroxide: white ppt., soluble in excess, giving a colourless solution
effect of aqueous ammonia: white ppt., soluble in excess, giving a
colourless solution
What is the test for ammonia? (Test for gases)
turns damp red litmus paper blue
What is the test for carbon dioxide?
(Test for gases)
turns limewater milky
What is the test for chlorine? (Test for gases)
bleaches a damp litmus paper
What is the test for hydrogen? (Test for gases)
‘pops’ with a lighted splint
What is the test for oxygen? (Test for gases)
relights glowing splint
What colour does lithium turn in the flame tests for metal ions?
Red
What colour does sodium turn in the flame tests for metal ions?
Yellow
What colour does potassium turn in the flame tests for metal ions?
Lilac
What colour does copper (II) turn in the flame tests for metal ions?
Blue-green
Name some properties of acids
- pH below 7
- Sour taste, corrosive
- When added to water, they form positively charged hydrogen ions
- Turn litmus paper red
- Bases are usually oxides or hydroxides of metals
- When alkalis are added to water, they form negative hydroxide ions (OH–)
What is used to measure the pH?
Universal indicator
What colour would the universal indicator if the pH was neutral?
Green
What colour would the universal indicator if the pH was very acidic?
Red
What colour would the universal indicator if the pH was a weak acid?
yellow/orange
What colour would the universal indicator if the pH was very alkaline?
Purple
What colour would the universal indicator if the pH was a weak alkaline?
Blue
Are acids proton donors or proton acceptors?
Acids are proton donors as they ionise in solution producing protons, which are H+ ions
Are bases proton donors or proton acceptors?
Bases are proton acceptors as they accept the protons which are donated by the acid
