Bases And Alkalis (T4) Flashcards
What is the pH of alkaline solutions?
More than 7
What affect does the strength of the alkali have on the pH of a solution?
The stronger the alkali the higher the pH number
What are bases and alkalis.
Bases are substances that can react with acids and neutralise them to make a salt and water.
Bases that dissolve in water are called alkalis.
What form do bases and alkalis usually take?
They are usually metal oxides or metal hydroxides.
Why is copper oxide not an alkali?
Because it does not dissolve in water.
Why is sodium hydroxide an alkali?
Because it does dissolve in water. It is a base AND an alkali.
What do alkalis do to red litmus paper?
The turn red litmus paper blue.
What colour do alkalis turn universal indicator?
Dark blue or purple if they are strong, blue-green if they are weak.
Whilst acids need hydrogen ions, alkali need…..
Hydroxide ions (OH-)
All alkalis are ……. but only soluble bases are ……..
All alkalis are bases but only soluble bases are alkalis
What is a common alkali used in the school laboratory?
Sodium hydroxide solution
List some instances where bases and alkalis are found and used at home…
- bases react with oils and fats, so they are often used in strong household cleaners. For example, drain and oven cleaners usually contain sodium hydroxide
- ammonia is commonly used in cleaners and can be recognised by its choking smell
- weak bases and alkalis are found in toothpaste, antacid tablets and baking powder
