acid + base class # 1 ob: intro to arrhenius theory, meet and greet tables k, l, and m

Acid + Base Class # 1

OB: intro to Arrhenius theory, meet and greet tables K, L, and M

Acids and bases always starts with a good story. A long, long time ago, in a galaxy far, far away…

Please note, a great mustache!

1. Svante ArrheniusFather of the Arrhenius Theory of Acids and BasesNobel Prize WinnerSwedish Chemist Extraordinaire

The Arrhenius Theory of Acids and Bases covers nearly 99% of all acids and bases, and allowed chemists of all levels to finally grasp what acids and bases were, how they worked, and what happens when you put them together.

There are other theories, for the 1% of solutions, including ammonia, which is important for us to also learn about as well. Arrhenius theory is nearly complete.

The standard theory (Arrhenius) states that:

2. ACIDS are aqueous solutions containing an excess of hydrogen ions (the H+1 ions exceed the hydroxide ion concentration).

Arrhenius theory states that:3. BASES are aqueous solutions containing an excess of hydroxide ions (the OH-1 exceed the hydrogen ion concentration).

ACIDS4. Acids we need to know are all listed in table K.

In our class we will discuss all eight acids, hydrochloric, nitrous, nitric, sulfurous, sulfuric, phosphoric, carbonic, and acetic (which is also known

as ethanoic acid during organic chem, and as vinegar over dinner).

Let’s look at table K now.

On it we’ll write near the top – STRONGEST ACIDS

and near the bottom – WEAKEST ACIDS

6. Acids are strong when there are lots of H+1 ions in solution, because the compounds dissociate well.

When HCl is put into water, practically all of the HCl becomes H+1 and Cl-1 ions

7. The more hydrogen ions in solution, the stronger the acid.

8. HCl dissociates very well. At the top of the list, the acids dissociate the easiest.

9. Further down, especially acetic acid (vinegar) the acids do not dissociate well at all. Much of those compounds dissolve into water as a polar molecules.

10. Only a SMALL PERCENT of the molecules actually ionize.

Acid goes into water Dissociates this way

11 HCl(G) + H2O(L)

12 HNO2(G) + H2O(L)

14 HNO3(G) + H2O(L)

15 H2SO4(G) + H2O(L)

16 H3PO4(G) + H2O(L)

17 H2CO3(G) + H2O(L)

18 HC2H3O2(G) + H2O(L)

Acid goes into water Dissociates this way*

11 HCl(G) + H2O(L) H+1(AQ) + Cl-1(AQ)

12 HNO2(G) + H2O(L) H+1(AQ) + NO2

-1(AQ)

14 HNO3(G) + H2O(L) H+1(AQ) + NO3

-1(AQ)

15 H2SO4(G) + H2O(L) H+1(AQ) + H+1

(AQ) + SO4-2

(AQ)

16* H3PO4(G) + H2O(L) H+1(AQ) + H+1

(AQ) + H+1(AQ) + PO4

-3(AQ)

17* H2CO3(G) + H2O(L) H+1(AQ) + H+1

(AQ) + CO3-2

(AQ)

18* HC2H3O2(S) + H2O(L) H+1(AQ) + C2H3O2

-1(AQ)

Acid goes into water Dissociates this way*

19 H3PO4(G) + H2O(L) H3PO4(AQ) + H+1(AQ) + H+1

(AQ) + H+1(AQ) + PO4

-3(AQ)

20 H2CO3(G) + H2O(L) H2CO3(AQ) + H+1(AQ) + H+1

(AQ) + CO3-2

(AQ)

21 HC2H3O2(G) + H2O(L) HC2H3O2(AQ) + H+1(AQ) + C2H3O2

-1(AQ)

These 3 weak acids do not dissociate totally. Most of the original molecule remains a polar molecule in solution.

Since the molecules do not dissociate totally, the number of hydrogen ions is not as big as it appears. It’s actually in a dynamic equilibrium back and forth through the arrow. You can easily drink 1.0 M acetic acid (the last one is vinegar) but drinking a 1.0 M strong acid = death.

BASES22. Bases we need to know are all listed in table L.

In our class we will discuss all 4 bases, sodium hydroxide, potassium hydroxide, calcium hydroxide, and ammonia. 23. Ammonia does not have hydroxides in its formula, but since it is a common and “normal” part of our regular lives, we will learn a separate theory to explain how it is a base.

24. Bases have more OH-1 in solution than H+1 ions.

Let’s look at table L now.

25. On it we’ll write near the top – STRONGEST BASES

and near the bottom – WEAKEST BASES

Bases are strong when there are lots of OH-1 ions in solution, because the compounds dissociate well.

When NaOH is put into water, nearly all of the NaOH becomes Na+1 and OH-1 ions

26. The more OH-1 ions in solution, the stronger the base.

27. The bases at the top of the list dissociate the easiest.

28. Ammonia follows a different rule, which we will not cover today. It is a base, it acts like a base, but it’s different too. Any other ionic compounds that are aqueous (and which will ionize in water) will also be bases.

29. Strong acids & strong bases have lots of ions in solution.

30. Strong acids & strong bases make good electrolytes, they will conduct electricity well because of all the loose ions they have in solution.

31. For example: HCl(AQ) conducts better than H2CO3(AQ) or H3PO4(AQ)

32. For example: NaOH(AQ) conducts better than NH3(AQ)

33. All acids and all bases are electrolytes.

34. Their electrolyte strengths (their ability to conduct electricity) are also top to bottom on tables K and L.

Arrhenius theory states that aqueous solutions with excess hydrogen ions are acids, and that aqueous solutions with excess hydroxide ions are bases. It goes on to say…

35. Acids + bases neutralize each other into water + a salt

36. Salts are ionic compounds (metal + nonmetal).

37. The formula for water is H20(L)

38. It can also be written as HOH(L)

39. Combining acids + bases to react are sort of fancy double replacement reactions, but the reactants must be an acid and base, and will always create a salt and water. There will be no precipitates either.

Let’s do the classic one first, then lots more…

40. HCl(AQ) + NaOH(AQ)

HCl(AQ) + NaOH(AQ)

The hydrogen ion, and the hydroxide ion are both red. Those ions make the acid and

the base. They get together to NEUTRALIZE each other.

Combining acids and bases to react are sort of fancy double replacement reactions, but the reactants must be an acid and base, and will always create a salt and water. There will be no precipitates either.

Let’s do the classic one first, then lots more…

HCl(AQ) + NaOH(AQ)

HCl(AQ) + NaOH(AQ) HOH(L) + NaCl(AQ)

The hydrogen ion and hydroxide ion make the water. The other ions make the salt,

in this case the salt is sodium chloride.

Write chemical formulas for these acid base neutralization reactions…

41. Nitric acid + potassium hydroxide

42. Hydrochloric acid and calcium hydroxide

Remember… start at the beginning, products are HOH + a salt

HNO3(AQ) + KOH(AQ)

HCl(AQ) + Ca(OH)2(AQ)

41. HNO3(AQ) + KOH(AQ) KNO3(AQ) + HOH(L)

42. 2HCl(AQ) + Ca(OH)2(AQ) CaCl2(AQ) + 2HOH(L)

Write chemical formulas for these acid base neutralization reactions…

43. Phosphoric acid plus lithium hydroxide

44. Nitric Acid and Magnesium hydroxide

Remember… start at the beginning, products are HOH + salt

43. H3PO4(AQ) + LiOH(AQ)

44. HNO3(AQ) + Mg(OH)2(AQ)

43. H3PO4(AQ) + 3LiOH(AQ) Li3PO4(AQ) + 3HOH(L)

44. 2HNO3(AQ) + Mg(OH)2(AQ) Mg(NO3)2(AQ) + 2HOH(L)

Homework tonight…

Print out and read the Acid Base BASICS

Go to arbuiso.com and look at the side of the home page and find the acid base link. Click it: look over what’s there.

Acid Base HW #1 will be collected tomorrow.

Buy a red Barron’s Regents Review book as soon as possible.

Acid Base Class # 2

OB: alternate theory of ammonia being a base, strengths of acids and bases measured as pH, and acid base indicator chemicals

45. An alternate theory, the Bronsted-Lowry Theory, defines ammonia as a base because of how it acts

when put into water. 46. This theory (in our class) is ONLY for AMMONIA. It could be applied to other

acids and other bases, but not in high school.

47. There are even OTHER theories that explain acids and bases (but who cares?)

99%Almost ALL acids and bases are ARRHENIUS acids and bases,and follow a nice, easy to remember, Nobel Prize winning plan:Acids have excess H+1 ions in solution, while Bases have excess OH-1 ions in solution.

Ammonia is a weak base, but seemingly does not follow the Arrhenius theory, it has NO HYDROXIDES in it’s formula.

1

48. NH3(G) + HOH(L)

Slowly we will see what happens, and provide the wording to help make you see what happens.

NH3(G) + HOH(L) NH4+1

(AQ) + OH-

1(AQ)

49. When put into water, the MOLECULE ammonia is sometimes able to break open water molecules from HOH → H+1 + OH-1

50. This happens to only about 25% of the ammonia molecules. Most are just NH3(AQ)

NH3(G) + HOH(L) NH4+1

(AQ) + OH-

1(AQ)

Although the ammonia has no hydroxide ions, the water ends up “providing” the needed OH-1 ions to the solution to make the properties of a base.

This theory tries to make ammonia the base, but it’s the hydroxides in solution.(just ask Arrhenius!)

The technical reason ammonia is a base, according to this alternate theory is:

51. Any compound capable of accepting a H+1 ion, is a base. NH3 accepts the H+1

52. By definition, water, which donates the H+1 is an acid. Water donated the H+1

This theory specifically does not “notice” the hydroxides in solution, otherwise Arrhenius would get the credit.

Measuring the strengths of acids and bases.

We will use a quantitative scale called pH to do this. The math for pH is outside the scope of our class, but not crazy hard. Here goes:

53. pH = -log[H+1]54. Which means the pH, the strength of an acid (or base) is equal to the

negative logarithm of the hydrogen ion concentration

0 7 14

55. The pH scale runs from zero to 14, with 7.0 being exactly in the middle.

56. A pH below 7 means that an acid is present, there are more H+1 ions in solution than OH-1 ions.

57. A pH above 7.0 means that the solution is basic, that there are more hydroxide ions than hydrogen ions in solution.

58. If pH is exactly 7, that means the concentration of H+1 ions = OH-1 ions. Every H+1 ion connects to a OH-1 ion, to form water (neither acid nor base).

acids bases

What the math means…

59. A pH of 1.0 means that the H+1 concentration in the solution is

1 x 10-1 moles H+1 per liter = one tenth of a mole of H+1 ions/liter

or… 6.02 x 1022 H+1 ions/liter

60. A pH of 2.0 means that the H+1 concentration in the solution is

1 x 10-2 moles H+1 per liter = one hundredth of a mole of H+1 ions/liter

or… 6.02 x 1021 H+1 ions/liter

• pH 1.0• pH 2.0• pH 3.0• pH 4.0• pH 5.0• pH 6.0• pH 7.0

1x10-1 moles H+1 ions/liter = 6.02 x 1022 H+1 ions/liter







H+1 concentration

61. As the pH increases, each full step reduces the hydrogen ion concentration by 10x (that’s what a log scale does, like the Richter scale for earthquakes, each numeric change is a 10x change in strength).

• pH 8.0• pH 9.0• pH 10.0• pH 11.0• pH 12.0• pH 13.0• pH 14.0








H+1 concentration

62. As pH moves higher, the amount of hydrogen ions reduces and reduces. Each step of pH is a 10x change in hydrogen ion concentration.

Table M Acid Base Indicators63. Acid Base indicators are compounds that change color, depending upon the pH (hydrogen ion concentration) of the solution.

64. Acid Base Indicators work by dynamic equilibrium.

It turns out that a variety of compounds will change colors depending upon the hydrogen ion concentration. In table M there are six compounds that have color ranges that are unique.

Let’s look at Methyl Orange first. The table states that Methyl orange changes color from RED to YELLOW between the pH values of 3.1 and 4.4

What that means is that for strong acid solutions (lower than 3.1) this indicator would turn RED in those solutions.

If the solution was a weak acid, say over 4.4 all the way to 7.0, it would be YELLOW. If the solution were a base (over 7 all the way to 14) it would be yellow.

If you have 14 solutions, all with pH values of 1 through 14, what color would methyl orange show in them?

65. Methyl orange in solution, changes color from red → yellow when the pH changes from 3.1 → 4.4

pHColor of solution

with methyl orange

1 RED

2 RED

3 RED

4 COLOR CHANGE

5 YELLOW

6 YELLOW

7 YELLOW

8 YELLOW

9 YELLOW

10 YELLOW

11 etc…. YELLOW

66. This indicator Methyl Orange CANNOT tell you the exact pH of a solution (none can) but it can INDICATE a range of pH.

67. If a solution is RED with methyl orange, it has a pH between 0 and 3.1 (it’s a pretty strong acid) (don’t drink it)

68. If a solution is YELLOW with methyl orange in it, it has a pH over 4.4 That would be a weak acid, a very weak acid, neutral, a weak base, or a strong base. Is it safe to drink? You CANNOT TELL.

69. If a solution is ORANGY COLORED (between red and yellow) with methyl orange in it, the pH of that solution would be somewhere between 3.1 and 4.4

70. Can you see the COLOR EXACTLY? NO! Neither can I. The acid base indicators only give you an INDICATION OF ABOUT what the pH is.

71. Let’s draw how these six indicators will change colors. You need to use color pencils to fill in the boxes according to what table M tells you.

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14

pH

Methyl orange

3.1 4.4 7

This shows that the methyl orange indicator will be red for pH below 3.2, yellow when the solution pH is above 4.4, and will be changing from red → yellow between pH 3.1 and 4.4

It indicates to us what the approximate pH of the solution is. Not exactly, but approximately. Do this for the next 5 indicators as well.

71. Arrhenius Acid + Arrhenius Base water + a salt

HCl(AQ) + NaOH(AQ) HOH(L) + NaCl(AQ)

72. In an acid base neutralization that is balanced, each hydrogen ion is combined with a hydroxide ion.

73. Each pair of ions makes a molecule of water. If it is truly neutralized, there are no left over ions, they are all balanced into water.

In most cases, without careful measuring, and knowledge of the strengths of the acid and base, you could not easily neutralize an acid and base.

There is math to help us. It’s called TITRATION MATH, because it’s used with the lab technique called titration, where neutralization occurs.

74. We’ll use a burette to measure acids and bases carefully.

They’re long glass tubes with lots of lines to measure the solutions. They have very fine nozzles, that will allow only the smallest drops out at a time (or a thin rushing stream).

Acid in beaker, known volume + UNKNOWN MOLARITY

Base of measured volume, known molarity

Also contains an ACID BASE indicator

75. By dripping in slowly the base, at some point the indicator will change colors, telling us we are at neutral. We can measure how much base we used, and we measured the volume of acid also. Time for MATH.

Acid in beaker, known volume + UNKNOWN MOLARITY

Base of measured volume, known molarity

Also contains an ACID BASE indicator

Before we can learn the titration formula, we have to think about an important thing, then we need to FIX the reference table so you never make dopey mistakes.

76. Acids + Bases both ionize in water.

77. Some, like HCl will make just ONE H+1 ion per mole

78. H2SO4 → 2 moles of H+1 /mole because it has 2 H+1 ions in the formula

79. H3PO4 → 3 moles of H+1 ions/mole

80. NaOH → 1 mole of OH-1 ions/ mole

81. Mg(OH) 2 → 2 moles of OH-1 ions/ mole

These are not all going to be 1:1 type math problems, but the formula on the reference table won’t help you think this though. Got it?

(Molarity of Acid)(volume of acid) = (molarity of Base)(volume of base)

(MA)(VA) = (MB)(VB)

This is the formula, but we MUST change it Before We Even Discuss it to this:

(#82)

(#H+1)(MA)(VA) = (MB)(VB)(#OH-1)

86. How much NaOH of 0.250M is needed to neutralize 83.0 mL of 1.00 M HCl ? (formula!)

86.

How much NaOH of 0.250M is needed to neutralize 83.0 mL of 1.00 M HCl ? (formula!)

(#H+1)(MA)(VA) = (MB)(VB)(#OH-1)

(1)(1.00 M)(83.0 mL) = (0.250 M)(VB)(1)

332 mL = VB 3SF

Start Volume in mL

End Volume in mL

87. We measure “upside down” with burettes. Be careful. Measure to the nearest 10 mL.

88. We will use indicators to tell us when we reach neutral.

89, Strangely we’ll use phenolphthalein, which changes from pH 8 to pH 9.

How can this be, if we’re looking for neutral???

It will get slightly complicated right now.

Neutral is when the # the H+1 ions = # OH-1

90. At pH 7.000, the concentration of H+1 = concentration of OH-1 ions.

91. This can be written as [H+1] = [OH-1 ]

In lab, when your acid and base are being neutralized in your mixing beaker, you are

(92) within one drop of neutral with phenolphthalein.

You can’t get much closer than that in high school chem lab. You could use an electronic pH meter to get to exactly 7.0000 pH, but it’s really close enough anyway. Besides, we all know you won’t read the burette scale perfectly anyway. It’s just percent error.

93. Your burette has 48.0 mL of 1.20 M NaOH and you titrate 75.0 mL HCl that has a few drops of phenolphthalein indicator. You end with 27.0 mL of NaOH in the burette, and you are as close to neutral as you can measure. What is the molarity of the acid?

(hint, first figure out how much of the base you used)

Base start volume =

Base end volume =

Base used in titration =

Then write the whole titration math formula. Go!

Your burette has 48.0 mL of 1.20 M NaOH and you titrate 75.0 mL HCl that has a few drops of phenolphthalein indicator. You end with 27.0 mL of NaOH in the buret, and you are as close to neutral as you can measure. What is the molarity of the acid?

(1)(MA)(VA) = (MB)(VB)(1)

(MA)(75.0 mL) = (1.20M)(21.0 mL)

MA = 0.336 M

94. It takes 12.4 mL of 1.90 M HCl to exactly neutralize 104 mL of NaOH. What is the molarity of the base?

94. It takes 12.4 mL of 1.90 M HCl to exactly neutralize 104 mL of NaOH. What is the molarity of the base?

(1)(MA)(VA) = (MB)(VB)(1)

(1.90 M)(12.4 mL) = (MB)(104 mL)

0.227 M = MB

95. You need 782.2 mL of KOH base to neutralize exactly 1500. mL nitric acid that has a 4.56 M. What is the molarity of this base?Hint: write the formula every time!

95. You need 782.2 mL of KOH base to neutralize exactly 1500. mL nitric acid that has a 4.56 M. What is the molarity of this base?

(1)(MA)(VA) = (MB)(VB)(1)

(4.56 M)(1500. mL) = (MB)(782.2 mL)

8.74 M = MB

96. What volume of 3.75 M H2SO4(AQ) is necessary to exactly neutralize 34.7 liters of 1.88 M KOH?

96. What volume of 3.75 M H2SO4(AQ) is necessary to exactly neutralize 34.7 liters of 1.88 M KOH?

(2)(MA)(VA) = (MB)(VB)(1)

Finally this extra part of the formula makes a HUGE

DIFFERENCE

The acid is 2x as acidic as the base, and without this adjustment, the math is just plain wrong.

96. What volume of 3.75 M H2SO4(AQ) is necessary to

exactly neutralize 34.7 liters of 1.88 M KOH?

(2)(MA)(VA) = (MB)(VB)(1)

(2)(3.75 M)(VA) = (1.88 M)(34.7 L)(1)

VA =

VA = 8.70 Liters (3SF)

(1.88 M)(34.7 L)(1)(2)(3.75 M)

97. 12.45 mL of 2.00 M H3PO4 is exactly neutralized with 25.33 mL Be(OH)2. What is the molarity of the base? (think: how many ions of each for formula?)

(X)(MA)(VA) = (MB)(VB)(Y)

( )(MA)(VA) = (MB)(VB)( )

Now do the math!

97. 12.45 mL of 2.00 M H3PO4 is exactly neutralized with 25.33 mL Be(OH)2. What is the molarity of the base? (think: how many ions of each for formula?)

(3)(MA)(VA) = (MB)(VB)(2)

(3)(2.00 M)(12.45 mL) = (MB)(25.33 mL)(2)

= MB = 1.47 M KOH

(3)(2.00 M)(12.45 mL)

(25.33 mL)(2)

Acid Base Class #4

OB: some of the loose ends of acids + bases, describing how acid base indicators work, and review of the titration math, including slightly more complex problems with different H+1 : OH-1 ion ratios.

Acid Base indicators are mostly weak acids.

When you put these indicators into solutions containing H+1 ions or OH-1 ions, they will undergo a LeChatelier's Shift - forward or reverse.

Since the indicator molecules or ions form are different colors, they will be one color or another, depending upon the pH.

Let’s look at the molecule phenolphthalein, since we used it in lab.

It’s a weak acid, which means it’s a molecule with a H+1 ion that sometimes ionizes off the molecule.

The formula for phenolphthalein is:

HC20H13O4

98. Show the dissociation of phenophthalein in H20

98. Phenolphthalein is a weak acid, with formula

HC20H13O4 H+1(AQ) + C20H13O4

-

1(AQ)

water

colorless molecule pink anion

If we

99. ADD BASE which way does this shift?

Phenolphthalein is a weak acid, with formula

HC20H13O4 H+1(AQ) + C20H13O4

-

1(AQ)

water


99. ADD BASE

In excess base, the H+1 ions + OH-1 ions → HOH making the reverse reaction less likely –

so it shifts forward, producing more pink anions.

This is why phenolphthalein turns pink with bases.


HC20H13O4 H+1(AQ) + C20H13O4

-

1(AQ)

water


If we

100. ADD ACID which way does this shift?


HC20H13O4 H+1(AQ) + C20H13O4

-

1(AQ)

water


100. ADD ACID

In excess acid, the pink anions have an easier time finding the hydrogen ions forming colorless molecules.

,

More collisions = faster reaction

The next slide contains the worst part of chemistry all year (for me). I must teach you this, I don’t understand why, there is NO NEED to try to grasp this other than it’s on the regents exam.

Forgive me, in advance.

Svante Arrhenius won a Nobel Prize for his theory of acids and bases.

Bronsted + Lowry made a name for themselves with ammonia being a base and their “alternate theory”.

Yet another way to “understand” acids, although thankfully with no names attached, is this:

The H+1 ions from the acid join H2O molecules this way:

101. H+1 + H2O H3O+1

The acid exists “as” part of a water molecule, called the hydronium ion. The H+1 ion becomes one with water.

You can believe this if you like, you might see it on the regents, but it seems unnecessary. Extra vocabulary…

102. Hydronium ion: a theoretical model for acids, whereby the hydrogen ions become one with water and exist as H3O+1

103. Acids can be described as:

H+1(AQ) Svante Arrhenius was right

Any compound that donates a H+1 ion, according to the Bronsted-Lowry theory (NH3, ammonia is a base because it ACCEPTS a H+1 ion)

H3O+1 the weird hydronium ion

p+1 or just as protons (what really is a hydrogen ion, if a hydrogen ion is a proton plus one electron, and the electron ionizes away to an anion, all that’s left is a proton.)

Write 4 balanced chemical equations for these word equations…

104. Hydrochloric acid + potassium hydroxide yields…

105. Sulfuric acid + beryllium hydroxide yields…

106. Nitrous acid + magnesium hydroxide yields…

107. Acetic acid + sodium hydroxide yields…

Write 4 balanced chemical equations for these word equations…

104. HCl(AQ) + KOH(AQ) HOH(L) + KCl(AQ)

105. H2SO4(AQ) + Be(OH)2(AQ) HOH(L) + CaSO4(AQ)

106. 2HNO2(AQ) + Mg(OH)2(AQ) HOH(L) + Mg(NO2)2(AQ)

107. HC2H3O2(AQ) + NaOH(AQ) HOH(L) + NaC2H3O2(AQ)

108. Show the dissociation for sulfurous acid into water. Use phase symbols.

109. Show the dissociation of potassium hydroxide in water as well. Use phase symbols.

108 + 109. Show the dissociation for sulfurous acid into water, then the dissociation of potassium hydroxide in water as well. Use phase symbols.

H2SO3(G) H+1(AQ) + H+1

(AQ) + SO3-1

(AQ)

KOH(S) K+1(AQ) + OH-1

(AQ)

water

water

110. How many milliliters of 1.25 M NaOH base can 12.0 mL of 2.50 M HCl acid neutralize?

110. How many milliliters of 1.25 M NaOH base can 12.0 mL of 2.50 M HCl acid neutralize?

(1)(MA)(VA) = (MB)(VB)(1)

(1)(2.50 M)(12.0 mL) = (1.25 M)(VB)(1)

24.0 mL = VB

This is an important time to point out that this acid is monoprotic (one H+1) per molecule. The base is also a “single hydroxide” base.

111. How many milliliters of 1.25 M NaOH base can 12.0 mL of 2.50 M H2SO4 acid neutralize?Note: this is a “double” acid AKA: diprotic, and a single hydroxide base.

111. How many milliliters of 1.25 M NaOH base can 12.0 mL of 2.50 M H2SO4 acid neutralize?To do this problem, we start with the same formula for titration math, but we make an important adjustment to take into account the “double acid” which has 2x the number of H+1 ions because it’s diprotic. The base is still a “single base” so we’ll multiply that side by one.

(2)(MA)(VA) = (MB)(VB)(1)

(2)(2.50 M)(12.0 mL) = (1.25 M)(VB)(1)

48.0 mL = VB

112. How many mL of H3PO4 acid of 1.15 M is needed to exactly neutralize 56.0 mL of2.50 M Mg(OH)2 base?

112. How many mL of H3PO4 acid of 1.15 M is needed to exactly neutralize 56.0 mL of 2.50 M Mg(OH)2 base? (triple acid, double base)

(3)(MA)(VA) = (MB)(VB)(2)

(3)(1.15 M)(VA) = (2.50 M)(56.0 mL)(2)

VA = 81.2 mL

114. How many mL of 0.760 M NaOH is required to neutralize 145 mL of 4.33 M HCl acid?

114. How many mL of 0.760 M NaOH is required to neutralize 145 mL of 4.33 M HCl acid?

(1)(MA)(VA) = (MB)(VB)(1)

(4.33 M)(145 mL) = (0.760 M)(VB)

826 mL = VBBoth of these are single: a monoprotic acid (single) with a single hydroxide base, no math correction needed.

Bromthymol Blue is an acid base indicator on table M, and it’s a weak acid. It does not dissociate well. It’s chemical formula be written as:

HC27H27Br2O5S115. Show this in dynamic equilibrium with the hydrogen ion and its larger anion. he molecule in water is yellow, and in a base, the anion appears blue. Include that under your dynamic equilibrium as well.

HC27H27Br2O5S H+1(AQ) + C27H27Br2O5S-1

(AQ)

YELLOW BLUE

Which way will LeChatelier Shift???

117. Add base OH-1

118. Add acid H+1

water

116.

HC27H27Br2O5S H+1(AQ) + C27H27Br2O5S-1

(AQ)

YELLOW BLUE

Which way will LeChatelier Shift???

117. Add base OH-1

118. Add acid H+1

LOOK AT TABLE MBromthymol blue changes from yellow to blue

from 6.0 to 7.6 Does this make sense?

water

Here are 3 problems in a row. You must write the formula, put in the correction multipliers where necessary, and fill in the formula’s second line. You do not have to complete the problems, just show the proper set up and formula.

119. You neutralize 134 mL of 2.45 M H3PO4(AQ) with 202 mL of KOH(AQ). What is the molarity of the base?

120. A bottle of 2,012 mL of 4.00 M NaOH(AQ) is spilled in lab. You use a weak hydrochloric acid of just 0.450 M to clean up. How many mL are used?

121. 45.6 mL nitric acid is neutralized with 33.2 mL calcium hydroxide solution of 1.24 M. What is strength of the acid?

119. MAVA = MBVB

(3)(2.45 M)(134 mL) = (MB)(202 mL)(1)

120. MAVA = MBVB

(1)(0.450 M)(VA) = (4.00 M)(2012 mL)(1)

121. MAVA = MBVB

(1)(MA)(45.6 mL) = (1.24 M)(33.2 mL)(2)

She’s calling Ghostbusters, for obvious reasons.

0 7 14

acids The pH scale bases

[H+1][OH-1]

122. Strong acids have lots of H+1 ions and few hydroxides.

123. Strong bases have lots of OH-1 ions and few hydrogen ions.

124. At pH 7.0, which is neutral - the H+1 ion concentration equals the OH-1 ions concentration. (or there are no ions)

125. That can be written as: [H+1] = [OH-1]

At pH 2.5 the hydrogen ion concentration is

1 x 10-2.5 moles H+1 ions per liter of solution.

Make sure, right now, you see where the exponent goes when describing the pH.

What is the pH of these 2 solutions?

126: 1 x 10-6.5 moles H+1 ions per liter of solution.

127: 1x 10-11.3 moles H+1 ions per liter of solution.

What is the pH of these 2 solutions?

126: 1 x 10-6.5 moles H+1 ions per liter of solution.

Solution A has a pH of 6.5

127: 1x 10-11.3 moles H+1 ions per liter of solution.

Solution B has a pH of 11.3

Let’s compare solutions on the left, to solutions on the right. Copy these 5 pairs, then use the example to do 128 →

Solution 1Solution

2 Solution 1 is…

ex pH 4.3 pH 6.3 100x more acidic128 pH 11.2 pH 13.2

129 pH 1.2 pH 0.2

130 pH 12.0 pH 8.0

131 pH 1.3

pH 6.3

Let’s compare solutions on the left, to solutions on the right. Copy these 5 pairs, then use the example to do 128 →

Solution 1Solution

2 Solution 1 is…

ex pH 4.3 pH 6.3 100x more acidic128 pH 11.2 pH 13.2 100 x less basic

129 pH 1.2 pH 0.2 10x less acidic

130 pH 12.0 pH 8.0 10,000x more basic

131 pH 1.3

pH 6.3 100,000x more acidic

132. You put some methyl orange indicator into your ammonia solution. What color does it change?

133. You put some bromthymol blue indicator into your vinegar, what color does it change?

134. You put some thymol blue into your deionized water, what color does it change?

135. You put some litmus into your potassium hydroxide

solution, what color does it change?

136. You put some bromcresol green into Mr. Arbuiso’s seltzer. What color is it now?

132. You put some methyl orange indicator into your ammonia solution. What color does it change? YELLOW

133. You put some bromthymol blue indicator into your vinegar, what color does it change? YELLOW

134. You put some thymol blue into your deionized water, what color does it change? BLUE

135. You put some litmus into your potassium hydroxide

solution, what color does it change? BLUE

136. You put some bromcresol green into Mr. Arbuiso’s seltzer. What color is it now? PROBABLY BLUE, it’s a really weak acid, and you get detention now.

137. Finish this drawing, include all arrows and labels, to completely outline how ammonia is a base according to the Bronsted-Lowry Theory…

NH3 + H2O

137.

NH3 + H2O NH4(AQ)+1 + OH-1

(AQ)

Ammonia accepts the H+1 ion, it’s a base

Water donates the H+1 ion, it’s therefore an acid

We really know that Svante was so smart, it’s the left over hydroxides that form the base properties, including being slippery on your fingers.

acid + base class # 1 ob: intro to arrhenius theory, meet and greet tables k, l, and m

Documents

aq h

hcl g h

aq slide

aq po

aq c

arrhenius theory of

weakest acids

strongest acids