Upload
ninda-dananingrum
View
272
Download
2
Embed Size (px)
Citation preview
8/13/2019 5.1 Acid, Alkalis, Salt
1/52
Acids, Alkalis and Salts
8/13/2019 5.1 Acid, Alkalis, Salt
2/52
INDICATORS
Students are able to: To identify the character of acid, base,
and salt by using an indicator
To classify substance in our daily livebased on acid, base, and salt concept
To use an indicator to know the pH of asubstance
Understand the concept of neutralizationreaction
8/13/2019 5.1 Acid, Alkalis, Salt
3/52
Acids
Most people think of acids as corrosiveliquids which bubbles when they come intocontact with solids and burn when theytouch the skin.
This description is true for many acids.
Some acids are not corrosive and are
found in our food. They give some foods their sour taste.
8/13/2019 5.1 Acid, Alkalis, Salt
4/52
The word acid comes from the Latin wordacidusmeaning sour.
The hazard symbol
for a corrosivesubstance.
8/13/2019 5.1 Acid, Alkalis, Salt
5/52
Examples of acids
Acids Animal origin
hydrochloric acid human stomach
lactic acid muscles during vigorous exercise
uric acid urine, excretory product from DNA in food
methanoic acid ant sting
8/13/2019 5.1 Acid, Alkalis, Salt
6/52
Acids Plant origin
citric acid orange and lemon juice
tartaric acid grapes
ascorbic acid vitamin C in citrus fruits
methanoic acid nettle sting
8/13/2019 5.1 Acid, Alkalis, Salt
7/52
Animals and plants that produce acid.
8/13/2019 5.1 Acid, Alkalis, Salt
8/52
Bottles of dilute and concentrated acids.
8/13/2019 5.1 Acid, Alkalis, Salt
9/52
Properties of Acids
Acids have a sour taste. Acids turn blue litmus paper red.
Acids react with some metals to give off
hydrogen gas. Acids react with metal carbonates to give
off carbon dioxide gas.
8/13/2019 5.1 Acid, Alkalis, Salt
10/52
Acids can be classified into two
types:Organic acids and Inorganic or mineral acids
The acids produced by plants and animals
(with the exception of hydrochloric acid) areknown as organic acids.
Ethanoic acid is an organic acid and was the
first to be used in experiments.
8/13/2019 5.1 Acid, Alkalis, Salt
11/52
The first mineral acid to be discovered wasnitric acid.
It was used to separate silver and gold.
These mineral acids are much stronger thanethanoic acid and allow more chemicalreactions to be made.
8/13/2019 5.1 Acid, Alkalis, Salt
12/52
Organic acids are weak acids; they are
often found in food.
Organic Acid Source
Citric Acid Oranges, Limes, Lemons
Tartaric Acid Grapes, Health salts, Baking powder
Malic Acid Apples, Goose berries, Grapes
Tannic Acid Tea
Acetic Acid Vinegar
8/13/2019 5.1 Acid, Alkalis, Salt
13/52
Organic Acids
Is an organiccompound with acidic properties. produced by plants and animals with the
exception of hydrochloric acid.
A few common examples include:
Formic acid-it is found in the stings and bitesof many insects of the order Hymenoptera,
mainly ants.
http://en.wikipedia.org/wiki/Organic_compoundhttp://rds.yahoo.com/_ylt=A0S020ntRRxIeUoBGG2JzbkF;_ylu=X3oDMTBxMHQ4cTkwBHBvcwM3BHNlYwNzcgR2dGlkA0kwODNfMTA1/SIG=1i8a0bv5a/EXP=1209898861/**http%3A//images.search.yahoo.com/images/view%3Fback=http%253A%252F%252Fimages.search.yahoo.com%252Fsearch%252Fimages%253Fp%253Dant%252Bsting%2526fr%253Dyfp-t-309%2526ei%253Dutf-8%2526js%253D1%2526x%253Dwrt%26w=500%26h=375%26imgurl=static.flickr.com%252F117%252F269134469_f6528d174f.jpg%26rurl=http%253A%252F%252Fwww.flickr.com%252Fphotos%252F42606934%2540N00%252F269134469%252F%26size=83.6kB%26name=Bulldog%20Ant%202%26p=ant%20sting%26type=JPG%26oid=37c12775ad640b02%26fusr=Ravenlike%26tit=Bulldog%20Ant%202%26hurl=http%3A//www.flickr.com/photos/42606934@N00/%26no=7&tt=386http://en.wikipedia.org/wiki/Organic_compound8/13/2019 5.1 Acid, Alkalis, Salt
14/52
Citric acid-is a weak organic acid. A naturalpreservative and is also used to add an acidic,
or sour, taste to foods and soft drinks.
Ethanoic acid or acetic acid- is found invinegar and is produced as wine becomessour.
http://rds.yahoo.com/_ylt=A0S020qnSRxI1SoArISJzbkF;_ylu=X3oDMTBxMmpma2wyBHBvcwMzBHNlYwNzcgR2dGlkA0kwODNfMTA1/SIG=1malqt7eu/EXP=1209899815/**http%3A//images.search.yahoo.com/images/view%3Fback=http%253A%252F%252Fimages.search.yahoo.com%252Fsearch%252Fimages%253Fp%253Dvinegar%2526fr%253Dyfp-t-309%2526ei%253Dutf-8%2526js%253D1%2526x%253Dwrt%26w=335%26h=500%26imgurl=static.flickr.com%252F1224%252F913232910_8ca6519e84.jpg%26rurl=http%253A%252F%252Fwww.flickr.com%252Fphotos%252F7937582%2540N03%252F913232910%252F%26size=97.6kB%26name=The%20Vinegar%20Light%20--%20A/K/A%3A%20%20The%20Very%20Wrong%20Lights%20Fear%20%C2%AE%26p=vinegar%26type=JPG%26oid=63f6dd70e1c5d150%26fusr=Mr.%20Monroe%26tit=The%20Vinegar%20Light%20--%20A/K/A%3A%20%20The%20Very%20Wrong%20Lights%20Fear%20%C2%AE%26hurl=http%3A//www.flickr.com/photos/7937582@N03/%26no=3&tt=146724http://rds.yahoo.com/_ylt=A0S0206JSRxI7kMBv0iJzbkF;_ylu=X3oDMTBxam9mbDR0BHBvcwM1BHNlYwNzcgR2dGlkA0kwODNfMTA1/SIG=1fifg32a2/EXP=1209899785/**http%3A//images.search.yahoo.com/images/view%3Fback=http%253A%252F%252Fimages.search.yahoo.com%252Fsearch%252Fimages%253Fp%253Dsoft%252Bdrinks%2526fr%253Dyfp-t-309%2526ei%253Dutf-8%2526js%253D1%2526x%253Dwrt%26w=192%26h=120%26imgurl=www.realfooddirect.co.uk%252Fimages%252Fcategories%252Fsoft-drinks.jpg%26rurl=http%253A%252F%252Fwww.cotswold-fayre.co.uk%252Findex.php%253FcPath%253D3%26size=10.1kB%26name=soft-drinks.jpg%26p=soft%20drinks%26type=JPG%26oid=9b54956ba440df44%26no=5&tt=559778/13/2019 5.1 Acid, Alkalis, Salt
15/52
Mineral acids
Derived from rocks or mineral sources
Mineral acids are strong acids
is an acid derived by chemical reaction from inorganic minerals, as opposed to
organic acids.
Mineral acids are very important tochemical procedures.
8/13/2019 5.1 Acid, Alkalis, Salt
16/52
A few common examplesinclude:
Hydrochloric acid-it is a strong acid, andthe major component of gastric acid. It isalso widely used in industry. It is a highly
corrosive solution.
Nitric acid-also known as aqua fortisandspirit of nitre, is a highly corrosive toxicstrong acid that can cause severe burns.
8/13/2019 5.1 Acid, Alkalis, Salt
17/52
Sulphuric acid-(H2SO4)is a strong mineral acid.
It is soluble in water at all concentrations.
Principal uses include ore processing fertilizers
manufacturing, oil refining, wastewater
processing, and chemical synthesis
8/13/2019 5.1 Acid, Alkalis, Salt
18/52
Acid rain Sulphur dioxide is produced by the
combustion of sulphur in a fuel when thefuel is burned.
Sulphur dioxide reacts with water vapour
and oxygen in the air to form sulphuricacid.
This may fall to the ground as acid rain oracid snow.
Oxides of nitrogen are converted to nitircacid in the atmospehre and thisfalls to the ground as acid rain or
acid snow.
8/13/2019 5.1 Acid, Alkalis, Salt
19/52
8/13/2019 5.1 Acid, Alkalis, Salt
20/52
The effect of acid rain Acid rain reaches the ground it drains into
the soil, dissolves some of the mineralsthere and carries them away. This processis called leaching.
The acid rain drains into rivers and. lakesand lowers the pH of the water.
If the pH changes, they die and the
animals that feed on them, such as fish,may also die.
8/13/2019 5.1 Acid, Alkalis, Salt
21/52
8/13/2019 5.1 Acid, Alkalis, Salt
22/52
Uses of AcidsAcid Uses
Citric acid Used in making fruit juice
Used as preservatives and flavouring agent in foodTartaric acid Used in making cakes
Used in health salts (efervescent tablets)
Tannic acid Used in tanning leather Used in dyeing fabrics
Used in making inkHydrochloricacid
Present in our stomach which helps in food digestionand kills bacteria
Used as rust remover
Sulphuric acid Used as electrolyte in car batteries Used as soda-acid fire extinguisher
Nitric acid Used to make fertilizers
Carbonic acid Used in making soft drinks
Ethanoic acid The diluted form is used in making vinegar Used as preservatives
8/13/2019 5.1 Acid, Alkalis, Salt
23/52
8/13/2019 5.1 Acid, Alkalis, Salt
24/52
Bases/Alkalis
As bases neutralize acids they aresometimes described as having propertieswhich are opposite to acids. Bases arehydrogencarbonates
A concentrated solution of an alkali iscorrosive and can burn the skin.
Can be found commonly in households Like acids there are strong and weak
alkalis
8/13/2019 5.1 Acid, Alkalis, Salt
25/52
Bases/Alkalis
Examples and uses of alkalis
http://rds.yahoo.com/_ylt=A0S0205DTxxI3k0BHbKJzbkF;_ylu=X3oDMTBxMmpma2wyBHBvcwMzBHNlYwNzcgR2dGlkA0kwODNfMTA1/SIG=1gintjomo/EXP=1209901251/**http%3A//images.search.yahoo.com/images/view%3Fback=http%253A%252F%252Fimages.search.yahoo.com%252Fsearch%252Fimages%253Fp%253Dsoap%2526fr%253Dyfp-t-309%2526ei%253Dutf-8%2526js%253D1%2526x%253Dwrt%26w=380%26h=305%26imgurl=www.istockphoto.com%252Ffile_thumbview_approve%252F218789%252F2%252Fistockphoto_218789_soap_bars.jpg%26rurl=http%253A%252F%252Fwww.istockphoto.com%252Fimageindex%252F218%252F7%252F218789%26size=22.4kB%26name=istockphoto_218789_soap_bars.jpg%26p=soap%26type=JPG%26oid=2e49a4de49463fae%26no=3&tt=1306579http://rds.yahoo.com/_ylt=A0S0200TTxxItWQAZRSJzbkF;_ylu=X3oDMTBycXBuanJxBHBvcwMxMQRzZWMDc3IEdnRpZANJMDgzXzEwNQ--/SIG=1g16f9o5p/EXP=1209901203/**http%3A//images.search.yahoo.com/images/view%3Fback=http%253A%252F%252Fimages.search.yahoo.com%252Fsearch%252Fimages%253Fp%253Dpaint%252Bremover%2526fr%253Dyfp-t-309%2526ei%253Dutf-8%2526js%253D1%2526x%253Dwrt%26w=200%26h=282%26imgurl=www.greenshop.co.uk%252Facatalog%252FPaint-Remover-1l.jpg%26rurl=http%253A%252F%252Fwww.greenshop.co.uk%252Facatalog%252FGreenshop_online_Home_Strip_110.html%26size=9.8kB%26name=Paint-Remover-1l.jpg%26p=paint%20remover%26type=JPG%26oid=34b337ac812d7f42%26no=11&tt=8406http://rds.yahoo.com/_ylt=A0S020uzThxI2w8Bg0aJzbkF;_ylu=X3oDMTByaDRlOWxkBHBvcwMxOARzZWMDc3IEdnRpZANJMDgzXzEwNQ--/SIG=1g2tm70p9/EXP=1209901107/**http%3A//images.search.yahoo.com/images/view%3Fback=http%253A%252F%252Fimages.search.yahoo.com%252Fsearch%252Fimages%253Fp%253Dfertilizers%2526fr%253Dyfp-t-309%2526ei%253Dutf-8%2526js%253D1%2526x%253Dwrt%26w=350%26h=232%26imgurl=www.ecofriend.org%252Fimages%252Fnitrogen_fertilizers_harmful_to_environment.jpg%26rurl=http%253A%252F%252Fwww.ecofriend.org%252Fpage%252F35%26size=15.7kB%26name=nitrogen_fertilizers_harmful_to_environment.jpg%26p=fertilizers%26type=JPG%26oid=b40f6cf8e8a9f89c%26no=18&tt=532798/13/2019 5.1 Acid, Alkalis, Salt
26/52
A concentrated solution of an alkali iscorrosive and can burn the skin. The samehazard symbol as the one used for acids(is used on containers of alkalis whenthey are transported.
Even dilute solutions of alkali such asdilute sodium hydroxide solution react
with fat on the surface of the skin andchange it into substances found in soap.
8/13/2019 5.1 Acid, Alkalis, Salt
27/52
Properties of Alkalis
Alkalis are bitter and have a soapy feel.
Some general properties of bases include:
Bitter taste (opposed to sour taste of acids)
Slimy or soapy feel on fingers
8/13/2019 5.1 Acid, Alkalis, Salt
28/52
Properties of Alkalis
Concentrated or strong bases are caustic(corrosive) on organic matter and reactviolently with acidic substances
Aqueous solutions or molten basesdissociate in ions and conduct electricity
Reactions with indicators: bases turn red
litmus paper blue and phenolpthalein red
8/13/2019 5.1 Acid, Alkalis, Salt
29/52
8/13/2019 5.1 Acid, Alkalis, Salt
30/52
Detecting acids and alkalis Some substance change colour when an
acid or an alkali is added to them. Litmus isa substance which is extracted from livingorganisms called lichen.
Blue litmus paper turns red when it comesinto contact with an acid.
Red litmus paper turns blue when it comesinto contact with an alkalis.
8/13/2019 5.1 Acid, Alkalis, Salt
31/52
Strong and weak acids andalkalis
The strength of an acid or alkali does notdescribe whether the solution is dilute orconcentrated.
It describes the ability of a substance toform particles called ions.
Acids form hydrogen ions and alkalis form
hydroxide ions.
8/13/2019 5.1 Acid, Alkalis, Salt
32/52
Strong acid forms a large number ofhydrogen ions and weak acid forms a small
number of hydrogen ions strong alkali forms a large number of
hydroxide ions and weak alkali forms a small
number of hydroxide ions The strength of an acid or alkali is
measured on the pH scale.
On this scale the strongest acid is 0and the strongest alkali is 14.
8/13/2019 5.1 Acid, Alkalis, Salt
33/52
A solution with a pH of 7 is neutral. It is
neither an acid nor an alkali.
A strong acid has a pH of 0-2, a weak acidhas a pH of 3-6; a weak alkali has a pH of
8-11 and a strong alkali has a pH of 12-14.
An electrical instrument called a pH meteris used to measure the pH of an acid or
alkali accurately.
8/13/2019 5.1 Acid, Alkalis, Salt
34/52
8/13/2019 5.1 Acid, Alkalis, Salt
35/52
For general laboratory use, the pH of an acidor an alkali is measured with universalindicator. This is made from a mixture of
indicators. Each indicator changes colour overpart of the range of the scale. By combiningthe indicators, a solution is made that givesvarious colours over the whole of the pHrange.
8/13/2019 5.1 Acid, Alkalis, Salt
36/52
8/13/2019 5.1 Acid, Alkalis, Salt
37/52
Mixing Acids and Alkalis
When acids mix with alkalis, a reactioncalled neutralization occurs in which saltand water are formed. This reaction can
be written as a general word equation:
acid + base salt + water
8/13/2019 5.1 Acid, Alkalis, Salt
38/52
Examplee.g. hydrochloric acid + magnesium Magnesium chloride + hydrogen gas
reacting acids with carbonates
e.g. Nitric acid + Lead carbonate Lead nitrate + Water + Carbon dioxide gas
2HNO3 + PbCO3 Pb(NO3)2 + H2O +CO2
8/13/2019 5.1 Acid, Alkalis, Salt
39/52
Using neutralization reactions
Sometimes the stomach produces toomuch acid, which causes indigestion. Theacid is neutralized by taking a tabletcontaining either magnesium hydroxide,
calcium carbonate, aluminum hydroxide orsodium hydrogencarbonate
8/13/2019 5.1 Acid, Alkalis, Salt
40/52
Acidity in the soil affects the growth ofcrops. It makes them produce less food. Lime(calcium hydroxide) is used to neutralizeacidity in soil. When it is applied to fields itmakes them appear temporarily white.
8/13/2019 5.1 Acid, Alkalis, Salt
41/52
Shampoos Toothpaste
Antacid tablet Fire extinguisher
Everyday uses of neutralisation
http://rds.yahoo.com/_ylt=A0S020rjVBxIuiwAsOGJzbkF;_ylu=X3oDMTBybTE3dWNpBHBvcwMxMgRzZWMDc3IEdnRpZANJMDgzXzEwNQ--/SIG=1fdagug0q/EXP=1209902691/**http%3A//images.search.yahoo.com/images/view%3Fback=http%253A%252F%252Fimages.search.yahoo.com%252Fsearch%252Fimages%253Fp%253Dfire%252Bextinguisher%2526fr%253Dyfp-t-309%2526ei%253Dutf-8%2526js%253D1%2526x%253Dwrt%26w=100%26h=127%26imgurl=www.stayingalive.ca%252Fimages%252Ffire_extinguisher1.jpg%26rurl=http%253A%252F%252Fwww.stayingalive.ca%252Fkitchen_safety.html%26size=2.8kB%26name=fire_extinguisher1.jpg%26p=fire%20extinguisher%26type=JPG%26oid=16efd0ef0f9de00a%26no=12&tt=61266http://rds.yahoo.com/_ylt=A0S0206EVBxInFYBF0uJzbkF;_ylu=X3oDMTBxMmpma2wyBHBvcwMzBHNlYwNzcgR2dGlkA0kwODNfMTA1/SIG=1jicngbsk/EXP=1209902596/**http%3A//images.search.yahoo.com/images/view%3Fback=http%253A%252F%252Fimages.search.yahoo.com%252Fsearch%252Fimages%253Fp%253Dantacid%252Btablets%2526fr%253Dyfp-t-309%2526ei%253Dutf-8%2526js%253D1%2526x%253Dwrt%26w=160%26h=160%26imgurl=www.health-care-beauty.com%252Fimages%252FAlka-Seltzer-Tablets-Antacid-Relief-Gold-36-ea-B000052WSE-M.jpg%26rurl=http%253A%252F%252Fwww.health-care-beauty.com%252FAlka-Seltzer-Tablets-Antacid-Relief-Gold-36-ea-B000052WSE.htm%26size=8.2kB%26name=Alka-Seltzer-Tablets-Antacid-Relief-Gold-36-ea-B000052WSE-M.jpg%26p=antacid%20tablets%26type=JPG%26oid=b66e8e41b171c962%26no=3&tt=353http://rds.yahoo.com/_ylt=A0S020rxUxxISTQA.7OJzbkF;_ylu=X3oDMTBxam9mbDR0BHBvcwM1BHNlYwNzcgR2dGlkA0kwODNfMTA1/SIG=1h22talli/EXP=1209902449/**http%3A//images.search.yahoo.com/images/view%3Fback=http%253A%252F%252Fimages.search.yahoo.com%252Fsearch%252Fimages%253Fp%253Dtoothpaste%2526fr%253Dyfp-t-309%2526ei%253Dutf-8%2526js%253D1%2526x%253Dwrt%26w=289%26h=425%26imgurl=www.westmifflinmoritz.com%252FFacts%252520of%252520the%252520Day%252520Pictures%252Ftoothpaste.bmp%26rurl=http%253A%252F%252Fwww.westmifflinmoritz.com%252FFact%252520of%252520the%252520Day%252FToothpaste.htm%26size=360.3kB%26name=toothpaste.bmp%26p=toothpaste%26type=bmp%26oid=b77928519df104ba%26no=5&tt=83341http://rds.yahoo.com/_ylt=A0S0203OUxxIsnAA3W.JzbkF;_ylu=X3oDMTBxa25vN3EyBHBvcwM5BHNlYwNzcgR2dGlkA0kwODNfMTA1/SIG=1gj7749dk/EXP=1209902414/**http%3A//images.search.yahoo.com/images/view%3Fback=http%253A%252F%252Fimages.search.yahoo.com%252Fsearch%252Fimages%253Fp%253Dshampoo%2526fr%253Dyfp-t-309%2526ei%253Dutf-8%2526js%253D1%2526x%253Dwrt%26w=300%26h=300%26imgurl=www.pup-n-stuff.com%252FProductImages%252Fimages%252Fshampoo%252520sampler.jpg%26rurl=http%253A%252F%252Fwww.pup-n-stuff.com%252Findex.asp%253FPageAction%253DVIEWPROD%2526amp%253BProdID%253D12%26size=22.8kB%26name=shampoo%20sampler.jpg%26p=shampoo%26type=JPG%26oid=32c131e0dd4d4e06%26no=9&tt=4227718/13/2019 5.1 Acid, Alkalis, Salt
42/52
Uses of AlkalisAlkali Uses
Sodium hydroxide Used to unclog drains and sinks as it eatsup organic matter in them Used to make soap
Potassium hydroxide Used to dye cloth Used in printing Used in making liquid soap
Used in paint varnish removal Used in electroplating
Calcium hydroxide Used in making cement and plaster Used to reduce the acidic condition is soil
Magnesium hydroxide Used in making toothpaste
Ammonia solution Used as a detergent Used as a bleaching agent
8/13/2019 5.1 Acid, Alkalis, Salt
43/52
8/13/2019 5.1 Acid, Alkalis, Salt
44/52
8/13/2019 5.1 Acid, Alkalis, Salt
45/52
Salts
Salts here do not refer only to table saltwhich we use for preserving food
Some salts are poisonous
eg. Salts of lead and mercury
When acid is added to a base, a salt isformed.
8/13/2019 5.1 Acid, Alkalis, Salt
46/52
A salt may be soluble or insoluble in water
Salt Solubility
Carbonates All carbonates are insoluble except forsodium, potassium and ammonium carbonates
Chlorides All chlorides are soluble except for silver and
lead chlorides
Nitrates All nitrates are soluble
Sulphates All sulphates are soluble except for barium,calcium and lead sulphates
8/13/2019 5.1 Acid, Alkalis, Salt
47/52
A soluble salt is first prepared as asolution and the crystals are then obtainedby evaporation
An insoluble salt is prepared byprecipitation where the solutes areobtained by filtration
8/13/2019 5.1 Acid, Alkalis, Salt
48/52
Salts Uses
Ammonium salts To make fertiliser
Calcium chloride As a drying agent
To increase the cement power inlime for wall plasters
Calcium sulphate To make plaster of Paris forfractures
Magnesium sulphate To make strong, mineral laxative
Potassium nitrate To make fertilisersTo make gun powder andfireworks
Sodium chloride As a food preservativeTo make chlorine gas
Silver chloride As a photographic film emulsion
Zinc sulphate As a wood and skin preservativeTo clarify glue
8/13/2019 5.1 Acid, Alkalis, Salt
49/52
8/13/2019 5.1 Acid, Alkalis, Salt
50/52
E i t
8/13/2019 5.1 Acid, Alkalis, Salt
51/52
Experimentthat can be done inside the classroom or inside
the laboratory
Things to bring: House hold items
a. Bebek b. Bayclin c. Wipol
d. Mama lemon e. Fiz f. Others
shampoo, vinegar
Fruits & Veg.
a. Tomato b. Apple c. Grapes
d. Orange/lime e. Manggo f. Others
tea, sprite , coke, salt, mylanta (antacid)
8/13/2019 5.1 Acid, Alkalis, Salt
52/52
Things to prepare :
(apparatus/materials needed)1.Litmus paper/phenolpthalein red
2. Universal indicator
3. Dropper & glass rod4. White tile
5. Test tube/ small container
6. Test tube rack7. beaker