Acids and Bases Chapter 23. Common Acids and NameFormulaStrong/WeakWhere is it found? Hydrochloric...
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Transcript of Acids and Bases Chapter 23. Common Acids and NameFormulaStrong/WeakWhere is it found? Hydrochloric...
Common Acids and
Name Formula Strong/Weak Where is it found?
Hydrochloric acid HCl Strong The stomach, in
the lab.
Sulphuric acid H2SO4 Strong Acid rain, car batteries, the lab.
Nitric acid HNO3 Strong Acid rain, in the
lab.
Ethanoic (acetic)
acidCH3COOH Weak Vinegar
Methanoic (formic) acid
HCOOH Weak Ant & nettle stings, descalers
Citric Acid C6H8O7 Weak Citrus fruits
Acids
• Acids are H+ or proton donors:
• Properties• Acids taste sour (e.g.
vinegar, lemon juice).• Acids are harmful to
living cells.• Aqueous solutions of
all acids contain hydrogen ions, H+.
Common Bases
Name Formula Where is it found?
Sodium hydroxide (caustic soda) NaOH Oven cleaners, in the lab.
Calcium hydroxide Ca(OH)2 Soil lime, limewater
Magnesium oxide (magnesia) MgO Indigestion tablets
Calcium carbonate CaCO3 Limestone, soil lime
Sodium hydrogencarbonate (bicarbonate)
NaHCO3 Baking powder
Ammonia NH3 Cleaning fluids, in the lab.
Base properties
• Most bases are oxides, hydroxides or carbonates of metals
• Soluble bases are known as alkalis.
• Aqueous solutions of alkalis contain hydroxide ions, OH-.
• Bases taste bitter. .• Bases feel slippery
Base and indicators
• Bases turn red litmus blue. A common indicator, used to detect the presence of a base, is phenolphthalein which, when mixed with a base, turns pink.
• Bases release hydroxide ions in water solutions.
• NaOH (s) + H2O (l) à Na1+ (aq) + OH1- (aq)
• NH4OH (aq) ß -> NH41+ (aq) + OH1- (aq)
pH scale
• Water is defined as having a pH value of 7- neutral.
• Acidic solutions have pH values below 7.
• Alkaline (basic) solutions have pH values above 7.
• pH is a measure of the number of hydronium or hydroxide ions
• Logrithimic scale
Reactions of Acids With metals
• Metals above copper in the reactivity series will react with acids, giving off hydrogen gas. The metal dissolves, forming a salt.
• METAL + ACID SALT + HYDROGEN
• ex. Mg(s) + H2SO4(aq) MgSO4(aq) + H2(g)
• This is why acids corrode metals, and must be stored in glass containers.
Base reactions
• With bases (metal oxides and hydroxides)
• The base dissolves in the acid and neutralises it. A salt is formed.
• ACID + BASE SALT + WATER
• ex. H2SO4(aq) + CuO(s) CuSO4(aq) + H2O(l)
• With metal carbonates• Metal + Base Salt +
water + CO2• 2HCl(aq) + CaCO3(s)
CaCl2(s) + H2O(l) + CO2(g)
•
Naming Acids
– Prefix is always hydro– Name the second element with the suffix -
ic
– HCl – hydrochloric– HF- Hydrofluoric
For the acid containing the most common polyatomic ion of its group simply use the first part of the polyatomic name and follow with the suffix ic.
For the acid containing the polyatomic with one less oxygen than the ic, use the suffix ous.
For the acid containing the polyatomic with two less oxygens than the ic, use the prefix hypo and the suffix ous.
• For an acid containing the polyatomic with one more oxygen than the ic, use the prefix per and the suffix ic.
Acid Reactions
ACID + BASE SALT + WATER
Hydrochloric Acid
+Sodium
Hydroxide Sodium
Chloride+ Water
HCl + NaOH NaCl + H2O
ACID + METAL SALT +HYDROGEN
GAS
Hydrochloric Acid
+ Magnesium Magnesium Chloride
+ Hydrogen
HCl + Mg MgCl2 + H2
ACID + CARBONATE SALT + WATER +
CARBON
DIOXIDE GAS
Hydrochloric Acid
+Calcium
CarbonateCalcium Chloride
+ Water +Carbon Dioxide
Molarity
• Molarity indicates the concentration • Given in the unit Moles/Liters
• Moles is the SI unit for quantity- it indicates 6.022 x1022 atoms or molecules of a substance
• It is equal to the atomic weight of the element in grams
• Ex. 16.00 g of O is one mole
• 32.00 g of O2 one mole
Neutralization
• Reactions in which an acid is added to a base cause neutralization
• This usually results in a salt and water
• IN the case of carbonate bases it results in a carbonate salt, water, and carbon dioxide