acids and bases

Question 1

what is an acid?

Answer 1

an acid is a substance that produces hydrogen ions(H+) when dissolved in water

Question 2

what does an acid do a litmus paper?

Answer 2

it turns a blue litmus paper red

Question 3

what can acidic solutions do?

Answer 3

acidic solutions can conduct electricity due to presence of mobile ions

Question 4

what is neutralisation?

Answer 4

acid+base=salt+water

Question 5

what is a base?

Answer 5

a base is a metal oxide or metal hydroxide that reacts with an acid to produce a salt and water only

Question 6

what is a base that is soluble in water called?

Answer 6

an alkali

Question 7

what is an alkali?

Answer 7

an alkali substance is a substance that produce hydroxide ions(OH-) when dissolved in water

Question 8

what does an alkali do to a litmus paper?

Answer 8

it turns a red litmus paper blue

Question 9

what are the reactions for alkalkis?

Answer 9

-alkali+acid=salt+water
-alkali+ammonia salt=salt+water+ammonia

Question 10

what is the reaction, alkali+acid=salt+water called?

Answer 10

neutralisation

Question 11

what is the ionic equation for acid and alkali?

Answer 11

always,
H+(aq)+OH-(aq)=H2O(l)

Question 12

what do the colours on the universal indicator mean?

Answer 12

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

Question 13

what is added to soil?

Answer 13

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

Question 14

explain the colours of the methyl orange indicator

Answer 14

yellow = pH>5, alkali
red = acid

Question 15

explain the colours of the phenolphthalein indicator

Answer 15

colourless = pH<8, acid
pink = alkali

Question 16

what is acidic?

Answer 16

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

Question 17

what is neutral?

Answer 17

neutral= non-metal oxides that do not react with acids and alkali
eg. nitrogen monoxide, carbon monoxide, water

Question 18

what is basic?

Answer 18

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

Question 19

what is amphoteric?

Answer 19

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)