acids and bases

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Cambridge IGCSE Biology Flashcards on acids and bases, created by ashley.amber on 30/05/2013.
ashley.amber
Flashcards by ashley.amber, updated more than 1 year ago
ashley.amber
Created by ashley.amber almost 11 years ago
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Resource summary

Question Answer
what is an indicator a substance that indicates the presence of an acid or soluble base by turning different colours
what colour does blue litmus turn in a) an acid b)a neutral substance c)an alkaline a)red b)purple c) blue
what colour does methyl orange turn in a)an acid b) a neutral substance c)an alkaline a)orange b)yellow c)yellow
what colour does phenophaylein turn in an alkaline? from colorless (in an acid and neutral) to pink
what does the pH scale measure? acidity and alkalinity of a substance dissolved in water
what are the features of a neutral substance? pH7 equal numbers of H+ and OH- ions
what are the features of an acid? bellow pH7 higher concentration of H+ ions (than pure water)
what are the features of an alkali? higher than pH7 higher concentration of OH- ions (than pure water)
what is the difference between a strong and weak acid? a strong acid has a higher concentration of H+ ions and a pH value between 0 and 3. a weak acid has a lower concentration of H+ ions and a pH value from between 3 and 6
give 3 examples of a strong acid and give their formulas. Hydrochloric- HCl Sulfuric- H2So4 Nitric- HNo3
give an example of a weak acid Ethanoic Citric
what does a base do? neutralizes acids
what does a base do? neutralizes acids
give 3 examples of a base and their formulas sodium hydroxide- NaOH magnesium oxide- MgO ammonia- NH3 (most metal oxides/hydroxides are bases)
what is an alkali? a soluable base which (when dissolved in water) is a source of OH- ions. all alkalis are bases but not all bases are alkalis.
what is the difference between strong and weak alkalis? a strong alkali solution has a high concentration of hydroxide ions and a pH from between 11-14. a weak alkali has a lower concentration of OH- and a pH value from between 8-11.
give 3 examples of common alkalis sodium hydroxide- NaOH calcium hydroxide- (Ca(OH)2) Ammonia- (NH3)
metal+acid=? salt+hydrogen
carbonate+acid=? salt+carbon dioxde+ water
how is acidity in soil affected by acid rain? It's neutralized by the calcium hydroxide in the rain (alkali)
acid+alkali=? water molecules
is a neutralization reaction endothermic or exothermic? exothermic (gives out heat)
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