Acids, Bases, Indicators, and Salts Flashcards
(23 cards)
How does litmus paper indicate acidity and alkalinity?
Red in acid, blue in alkali.
What colour is phenolphthalein in acid and alkali?
Colourless in acid, pink in alkali.
What colour is methyl orange in acid and alkali?
Red in acid, yellow in alkali.
How does the pH scale classify substances?
0–3: Strongly acidic
4–6: Weakly acidic
7: Neutral
8–10: Weakly alkaline
11–14: Strongly alkaline
What is universal indicator used for?
To measure the approximate pH of an aqueous solution based on colour.
What do acids produce in aqueous solution?
Hydrogen ions (H⁺).
What do alkalis produce in aqueous solution?
Hydroxide ions (OH⁻).
What happens when an alkali neutralises an acid?
A salt and water are formed.
Are all sodium, potassium, and ammonium compounds soluble?
Yes, all are soluble.
Are all nitrates soluble?
Yes.
Which chlorides are insoluble?
Silver chloride and lead(II) chloride.
Which sulfates are insoluble?
Barium sulfate, calcium sulfate, and lead(II) sulfate.
Which carbonates are soluble?
Sodium, potassium, and ammonium carbonates.
Which hydroxides are soluble?
Sodium, potassium, and calcium hydroxide (calcium hydroxide is only slightly soluble).
What is an acid in terms of proton transfer?
A proton donor.
What is the general reaction of an acid with a metal?
Acid + Metal → Salt + Hydrogen
What is the reaction of an acid with a base?
Acid + Base → Salt + Water
What is the reaction of an acid with a metal carbonate?
Acid + Metal carbonate → Salt + Water + Carbon dioxide
Which substances can act as bases?
Metal oxides, metal hydroxides, and ammonia.
What is the difference between a base and an alkali?
An alkali is a soluble base.
How can you prepare a pure, dry soluble salt from an insoluble base?
Add excess base to warm acid
Filter to remove excess base
Heat filtrate to concentrate
Leave to crystallise
Filter and dry the crystals
How do you prepare pure, dry hydrated copper(II) sulfate crystals from copper(II) oxide?
Add excess copper(II) oxide to warm sulfuric acid
Filter to remove unreacted copper(II) oxide
Heat the solution gently to concentrate
Leave to crystallise
Filter and dry the crystals
How do you carry out a flame test?
Clean a wire loop with HCl and heat it
Dip it in the solid sample
Hold it in a blue Bunsen flame
Observe the flame colour
