acids and bases Flashcards
what is an acid?
an acid is a substance that produces hydrogen ions(H+) when dissolved in water
what does an acid do a litmus paper?
it turns a blue litmus paper red
what can acidic solutions do?
acidic solutions can conduct electricity due to presence of mobile ions
what is neutralisation?
acid+base=salt+water
what is a base?
a base is a metal oxide or metal hydroxide that reacts with an acid to produce a salt and water only
what is a base that is soluble in water called?
an alkali
what is an alkali?
an alkali substance is a substance that produce hydroxide ions(OH-) when dissolved in water
what does an alkali do to a litmus paper?
it turns a red litmus paper blue
what are the reactions for alkalkis?
-alkali+acid=salt+water
-alkali+ammonia salt=salt+water+ammonia
what is the reaction, alkali+acid=salt+water called?
neutralisation
what is the ionic equation for acid and alkali?
always,
H+(aq)+OH-(aq)=H2O(l)
what do the colours on the universal indicator mean?
red, 0-2 = strong acid
orange, 3-4 = weak acid
yellow, 5-6 = weak(er) acid
green, 7 = neutral
blue, 8-11 weak alkali
violet, 12-14 = strong alkali
what is added to soil?
farmers add slaked lime/solid calcium hydroxide/Ca(OH)2 to neutralise the excess acid in the soil. this increases the pH of the soil and allow the plants to grow better
explain the colours of the methyl orange indicator
yellow = pH>5, alkali
red = acid
explain the colours of the phenolphthalein indicator
colourless = pH<8, acid
pink = alkali
what is acidic?
acidic= non-metal oxides that react with alkalis only
acidic oxides react with alkalis to form a salt and water
most acidic oxides dissolve in water to form an acid
eg. co2, sulfur dioxide, nitrogen dioxide, all non-metal dioxides except NO, CO, H2O
what is neutral?
neutral= non-metal oxides that do not react with acids and alkali
eg. nitrogen monoxide, carbon monoxide, water
what is basic?
basic= metal oxides that react with acids to form a salt and water
basic oxides such as sodium oxide and potassium oxide dissolve in water to form alkaline solutions
eg. copper(II) oxide, calcium oxide, sodium oxide, all metal oxides except zinc oxide, aluminum oxide, lead(II) oxide
what is amphoteric?
amphoteric= metal oxides that react with both acids and alklalis to form salt salt and water
eg. zinc oxide, aluminum oxide, lead(II) oxide only(TBC)
