acids

Question 1

list three properties of acids

Answer 1

sour taste
change blue litmus paper red
corrosive
electrolyte

Question 2

what is an acid

Answer 2

acid is a proton donor
loses its hydrogen ion when it is dissolved and forms salts

Question 3

ascorbic acid or vitamin c

Answer 3

C6H806
citrus fruits
west indian cherries
sweet peppers
tomatoes
green leafy vegetables
shortage leads to scurvy
on exposure to heat for example during cooking vit c is destroyed by being oxidised
sodium hydrogen carbonate sometimes is added to fruits and veg to improve texture and appearance but neutralises any vit c present reducing vit c content

Question 4

methanoic acid

Answer 4

HCOOH
in venom of bee and ant stings
causes itching redness swelling pain around sting
stings treated by applying paste of sodium hydrogen carbonate or calamine lotion which contains zinc hydrogen carbonate
both neutralise the acid

Question 5

lactic acid

Answer 5

C3H603
produced in muscle cells during strenuous activity
if too much lactic acid builds it prevents muscles from contracting and person collapses

Question 6

ethanoic acid or vinegar

Answer 6

CH3COOH
used to preserve food items
being acidic its low pH destroys or denatures enzymes which cause decay and inhibits growth of bacteria and fungi

Question 7

citric acid

Answer 7

C6H8O7
in citrus fruits such as limes
lime juice used to remove rust stains from clothes
acid in lime reacts with ironII oxide in rust stains making soluble compound which can be washed out of clothes

Question 8

what is the chemical equation for citric acid in removing rust stains

Answer 8

Fe2O2 + 6H – 2Fe +3H2O

Question 9

acid + metal

Answer 9

salt and hydrogen gas
metal by itself has no charge

Question 10

what shows evidence of hydrogen gas being produced

Answer 10

effervescence or bubbling or fizzing
if a lighted splint was held over mouth of test tube a pop sound is heard and splint is extinguished

Question 11

acid + metal oxide or metal hydroxide

Answer 11

salt and water

Question 12

what is a metal oxide or hydroxide

Answer 12

base and as such this is a neutralisation reaction

Question 13

reactivity series of metals

Answer 13

p
s
c
m
a
c
z
i
t
l
h
c
s
g

Question 14

acid + nitric acid

Answer 14

produces salt and nitrogen gas

Question 15

acid + carbonate or hydrogen carbonate

Answer 15

salt + water + carbon dioxide

Question 16

how to test for carbon dioxide

Answer 16

turns limewater cloudy white
limewater calcium hydroxide

Question 17

define acid anhydride

Answer 17

defined as non metal oxide which forms acidic solution when reacted with water
not all nonmetals oxides are acid anhydrides
such as carbon monoxide because does not react with water