physical science chapter 23 acids and bases
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Physical Science Chapter 23 Acids and Bases. LEQ: What techniques in the lab setting will be used to identify acids and bases?. LEQ: What techniques in the lab setting will be used to identify acids and bases?. Acids. Bases . Produce H+ ions in water Form hydronium ions (H 3 0+) - PowerPoint PPT PresentationTRANSCRIPT
Physical Science Chapter 23
Acids and BasesLEQ: What techniques in the lab setting will
be used to identify acids and bases?
LEQ: What techniques in the lab setting will be used to identify acids and bases?
Acids Bases Produce H+ ions in
waterForm hydronium
ions (H30+)Taste sourProduce hydrogen
gas when react with metals
Change litmus paper red
Produce OH- (hydroxide) ions in water
Feel slipperyTaste bitter, chalkyChange litmus
paper blue
LEQ: What techniques in the lab setting will be used to identify acids and bases?
How are they alike?CorrosiveReact with indicators and change colorConduct electricity (electrolytes)React with each other to form salt and
water
LEQ: What techniques in the lab setting will be used to identify acids and bases?
Common Acids
þ Soda
þ Coffee
þ Wine
þ Grapefruit (citric acid)
þ Yogurt (lactic acid)
þ Pickled foods in vinegar (acetic acid or CH₃COOH)
þ Fertilizers (sulfuric, nitric, phosphoric, HCL)
þ Car batteries (sulfuric acid or H₂SO₄)
LEQ: What techniques in the lab setting will be used to identify acids and bases?Common bases
Egg whites
Baking powder
Milk of magnesia Mg(OH)2
Antacids – Al(OH)3
Soap - NaOH
Shampoo
Ammonia - NH3
Oven cleaner -
NaOH
Drain cleaner -
NaOH
Fertilizers – NH3
LEQ: What techniques in the lab setting will be used to identify acids and bases?
What does it mean to dissociate?To break apartProcess in which an ionic compound separates into its positive and negative ions
LEQ: What techniques in the lab setting will be used to identify acids and bases?
How do acids dissociate in water and what products are formed?
The negative areas of nearby6 water molecules attract the positive hydrogen in the acid.
Produces a hydronium ion and an anion
LEQ: What techniques in the lab setting will be used to identify acids and bases?
How do bases dissociate in water and what products are formed?
The negative areas of nearby water molecule attract the positive ion in the base. The positive area of the water molecule attract the hydroxide ion.
Water molecules do not combine with the ions formed from the base.
Produces a positive ion, a hydroxide ion, and water
LEQ: What techniques in the lab setting will be used to identify acids and bases?
Explain how ammonia (NH3) is considered a base when it does not contain OH-.
The ammonia attracts a hydrogen from the water forming ammonium ion and a hydroxide ion.
LEQ: What techniques in the lab setting will be used to identify acids and bases?
Identify each as characteristic of an A) acid or B) base____ 1. Sour taste ____ 2. Produces OH- in aqueous solutions
____ 3. Chalky taste____ 4. Is an electrolyte____ 5. Produces H+ in aqueous solutions
LEQ: What techniques in the lab setting will be used to identify acids and bases?
Describe the solution in each of the following as: 1) acid 2) base or 3)neutral.A. ___soda
B. ___soapC. ___coffeeD. ___ wineE. ___ water
F. ___ grapefruit
LEQ: What techniques in the lab setting will be used to identify acids and bases?
Identify each as a characteristic of an A) acid or B) base_A_ 1. Sour taste_B_ 2. Produces OH- in aqueous solutions
_B_ 3. Chalky tasteA, B 4. Is an electrolyte_A_ 5. Produces H+ in aqueous solutions
LEQ: What techniques in the lab setting will be used to identify acids and bases?
Describe each solution as: 1) acid 2) base or 3) neutral.A. _1_ soda
B. _2_ soapC. _1_ coffeeD. _1_ wineE. _3_ water
F. _1_ grapefruit
LEQ: What techniques in the lab setting will be used to identify acids and bases?
Strong acids Weak acids Nearly all acids
molecules dissociate into ions
Strong electric currentSingle arrow in
chemical equationHCl + H2O H3O+ + Cl-
Example: HCl, HNO3, H2SO4
Partially dissociate into ions in water
Weak electric currentDouble arrow in
chemical equationCH3COOH + H2O
H3O+ + CH3COO-
Examples: acetic acid, carbonic acid
LEQ: What techniques in the lab setting will be used to identify acids and bases?
Differentiate between strong and weak bases.
Strong completely dissociates and weak partially dissociates.
NaOH Na + + OH-
NH3 + H2O NH4+ + OH-
LEQ: What techniques in the lab setting will be used to identify acids and bases?
Differentiate between strength and concentration.Strength
Strong or weakHow easily acids and bases dissociate in water
ConcentrationConcentrated – a large amount of acid or base in a given
amount of waterDiluted – a little acid or base in a large amount of water
Amount of acid or base dissolve
LEQ: What techniques in the lab setting will be used to identify acids and bases?
pH scale - measures how acidic or basic a solution is based on concentration of H+ions
Ways to test pHpH paperpH meter****litmus paper just tells if it is an acid or
base****Buffers – used to minimize the effects of acids
or bases on pH
pH lower than 7: acidic (high H+ concentration)pH higher than 7: basic (low H+ concentration)pH at 7: neutral
LEQ: What techniques in the lab setting will be used to identify acids and bases?
NeutralizationA chemical reaction between an acid and a base
that takes place in a water solutionH+ + OH- H2O
Cl- + Na+ NaClTherefore,
acid + base salt + waterHCl + NaOH H2O + NaCl
LEQ: What techniques in the lab setting will be used to identify acids and bases?
What is titration?When a solution of known concentration and
volume is used to determine the concentration of another solution
LEQ: What techniques in the lab setting will be used to identify acids and bases?
What are the steps of titration?Place a known volume of acid that has an unknown
concentration in a beakerAdd a few drops of phenolphthalein (indicator) to
beaker (colorless in acid but turns bright pink in base)Slowly add base solution of known concentration
(standard solution) to acid and indicator solution using the burette system
Continue to add base drop by drop until solution turns pink and the color persist (end solution/neutralization)
LEQ: What are some causes and effects of acid rain?
Causes:Burning of fossil fuels
Effects:Corrode or eat away at substancesDestroy plant and animal life
Solutions:Reduce pollutionAdd lime to acidic water
Differentiate between acids and basesAcids produce hydrogen ions which
attach to the water molecule forming a hydronium ion. They turn litmus paper red, are low on the pH scale and taste sour.
Bases produce hydroxide ions in solution. They turn litmus paper blue, have a high pH, and taste bitter or chalky.
How are acids and bases alike?Both acids and bases are corrosive
to metals and can burn tissue. They change colors in the presence of indicators. They both produce electrolytes meaning that they have the ability to conduct electricity. When they react with each other to form salt and water.
What is an example of an indicator?Litmus paperphenolphthalein
Explain the process of dissociation of bases and be specific on what products are produced.When a base is added to water, the
water molecule dissociates the base forming a cation and a hydroxide ion. The water molecule remains as a water molecule.
Explain the process of dissociation of acids and be specific on what products are produced.When an acid is added to water, the
negative side of the water molecule removes the hydrogen from the acid forming a hydronium ion and leaving an anion.
Explain in detail how ammonia dissociates in water. Explain how this proves that ammonia is a base.Ammonia does not have a hydroxide ion
as part of its formula. When ammonia is added to water, it removes a hydrogen ion from the water molecule leaving behind a hydroxide ion. The removed hydrogen attaches to the ammonia creating the ammonium ion. Due to the hydroxide ion being produced, this proves that ammonia is a base.
Differentiate between strong acids/bases and weak acids/bases.Strong acids and bases dissociate completely in
water. Strong acids have low pH numbers and strong bases have high pH numbers. Both of their equations contain a single arrow pointing toward the product side. Strong acids and bases both have the ability to produce a strong electric current.
Weak acids and bases partially dissociate in water. Their pH numbers are closer toward the middle of the pH scale with the exception to 7 (seven) which is neutral. Their equations contain a double arrow. Weak acids and bases only produce a small electric current.
Differentiate between strength and concentration.Strength refers to the ease at which acids
and bases dissociate in water. If they dissociate completely; then, they are strong. If they only partially dissociate; then, they are weak.
Concentration refers to the amount of acid or base present in a solution. The solution is considered concentrated if there is large amount of acid or base and little water. The solution is considered diluted if there is minimal amounts of acid or base in a large amount of water.
What is the purpose of buffers?Buffers are used to minimize the effects of
acids or bases on pH within the body so that the pH level of the body stays close to neutral.