Acids + Alkalis Flashcards
What are the three acids you need to know
Hydrochloride acid (HCl)
Nitric acid (HNO_3)
Sulfuric Acid (H_2SO_4)
What is special about hydrogen in acids?
Always forms a H+ ion (made up of only one proton, called a PROTON)
Cl-, NO3-, SO4 2-
State symbol of acids
Aq
What is the pH scale
Shows the acidity of a substance from 0-14, acid-alkali, 7=neutral
What are indicators
Tell you the if a substance is an acid or an alkali
List all the indicators and their colour changes
Universal indicator - (starts green - neutral dissolved in water) red-GREEN-purple shows level of acidity, ph scale
Red litmus - Red-RED-Blue
Blue litmus - red-BLUE-blue
Phenolphthalein- colourless-COLOURLESS-pink
Methyl orange - dark orange-ORANGE-yellow
Why may you sometimes use litmus paper instead of solution?
To test the acidity of gases
Advantages and disadvantages of UI to others
Ads: able to see the strength of acidity
Dis: not as clear to see if smthing is acid or alkali (less obvious colour changes compared to colourless-pink)
List the 4 reactions involving acids
Metal + Acid - Salt + Hydrogen
Ob: effervescence, metal disappears
Neutralisation Reactions
Acid + Alkali - salt + water
Acid + Metal Oxide - Salt + Water
Acid + metal carbonate - salt + water + carbon dioxide
Examples of bases
Alkali, metal carbonate, metal oxide
Definition of an acid
An acid is a PROTON DONOR - source of hydrogen ions H+
Definition of a base
A PROTON ACCEPTER
Definition of an alkali
A water soluble base which is a source of hydroxide ions OH-
(All group 1 metal hydroxides are alkalis)
What is neutralisation?
A reaction between an acid and a base where both the acid and the base are neutralised and water is formed
How is ammonia an ALKALI?
Reaction = ammonia + hydrogen chloride (acidic gas) - ammonium chloride
NH3 + HCl - NH4Cl (charges +1,-1)
The hydrogen chloride donates a proton forming the chloride ion xxxxxxxo
(Left behind Hydrogen shell reacts with ammonia) Ammonia molecule accepts a proton from the hydrogen chloride molecule forming the AMMONIUM ion.
Isn’t aq and isn’t a direct source of OH-
