What kind of an electrolyte is a weak base?

Teesta D.

University of Pittsburgh - Main Campus

How does Bronsted and Lowry's definition of an acid differ from Arrhenius's definition of an acid? Explain which definition is broader.

Charles T.

Numerade Educator

What is the conjugate acid of the base ammonia, $\mathrm{NH}_{3}$ ?

Teesta D.

University of Pittsburgh - Main Campus

What is the concentration of hydroxide ions in pure water?

Teesta D.

University of Pittsburgh - Main Campus

Give the equation that relates pH to hydronium ion concentration.

Charles T.

Numerade Educator

How does the strength of an acid relate to the concentration of the acid? How does the strength of an acid relate to the pH of an aqueous solution of the acid? How does the concentration of an acid solution relate to the solution's pH?

Teesta D.

University of Pittsburgh - Main Campus

What product do all neutralization reactions have in common?

Charles T.

Numerade Educator

At what point in a titration are the amounts of hydronium ions and hydroxide ions equal?

Teesta D.

University of Pittsburgh - Main Campus

Group the following four terms into two pairs according to how the terms are related, and explain how they are related: end point, standard solution, titrant, and transition range.

Charles T.

Numerade Educator

What is the equilibrium constant that is applied to a weak acid?

Teesta D.

University of Pittsburgh - Main Campus

How does the addition of a small amount of acid or base affect a buffered solution?

Charles T.

Numerade Educator

Compare the properties of an acid with those of a base.

Teesta D.

University of Pittsburgh - Main Campus

What is a base according to Arrhenius? according to Bronsted and Lowry?

Charles T.

Numerade Educator

Why are weak acids and weak bases poor electrical conductors?

Teesta D.

University of Pittsburgh - Main Campus

What is the difference between the strength and the concentration of an acid?

Charles T.

Numerade Educator

Identify each of the following compounds as an acid or a base according to the Bronsted-Lowry classification. For each species, write the formula and the name of its conjugate.

\begin{equation}

\begin{array}{l}{\text { a. } \mathrm{CH}_{3} \mathrm{COO}^{-}} \\ {\text { b. HCN }} \\ {\text { c. HOOCCOOH }} \\ {\text { d. } C_{6} \mathrm{H}_{5} \mathrm{NH}_{3}^{+}}\end{array}

\end{equation}

Teesta D.

University of Pittsburgh - Main Campus

Write an equation for the reaction between hydrocyanic acid, HCN, and water. Label the acid, base, conjugate acid, and conjugate base.

Charles T.

Numerade Educator

Write chemical equations that show how the hydrogen carbonate ion, HCO $_{3}^{-}$ acts as an amphoteric ion.

Teesta D.

University of Pittsburgh - Main Campus

Explain the relationship between the self-ionization of water and $K_{w}$ .

Charles T.

Numerade Educator

Write an equation that shows the self-ionization of water.

Teesta D.

University of Pittsburgh - Main Campus

Three solutions have pHs of $3,7,$ and $11 .$ Which solution is basic? Which is acidic? Which is neutral?

Charles T.

Numerade Educator

By what factor does $\left[\mathrm{OH}^{-}\right]$ change when the $\mathrm{pH}$ increases by 3$?$ by 2$?$ by 1 ? by 0.5$?$

Teesta D.

University of Pittsburgh - Main Campus

Explain how you can calculate pH from $\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]$ by using your calculator.

Charles T.

Numerade Educator

Describe two methods of measuring pH, and explain the advantages and disadvantages of each method.

Teesta D.

University of Pittsburgh - Main Campus

Describe two precautions that should be taken to ensure an accurate titration.

Teesta D.

University of Pittsburgh - Main Campus

How would you select an indicator for a particular acid-base titration?

Teesta D.

University of Pittsburgh - Main Campus

Would the $\mathrm{pH}$ at the equivalence point of a titration of a weak acid with a strong base be less than, equal to, or greater than 7.0$?$

Charles T.

Numerade Educator

Name an indicator you might use to titrate ammonia with hydrochloric acid.

Teesta D.

University of Pittsburgh - Main Campus

The $K_{a}$ of nitrous acid, $\mathrm{HNO}_{2},$ is $6.76 \times 10^{-4} .$ Write the equation describing the equilibrium established when $\mathrm{HNO}_{2}$ reacts with $\mathrm{NH}_{3} .$ Use unequal arrows to indicate whether reactants or products are favored.

Charles T.

Numerade Educator

$\begin{array}{l}{\text { a. What is the relationship between the }} \\ {\text { strength of an acid and the strength of }} \\ {\text { its conjugate base? }} \\ {\text { b. What is the realtionship between the }} \\ {\text { strength of a base and the strenght of }} \\ {\text { its conjugate acid? }}\end{array}$

Teesta D.

University of Pittsburgh - Main Campus

Propanoic acid, $\mathrm{C}_{2} \mathrm{H}_{5} \mathrm{COOH},$ is a weak acid. Write the expression defining its acid-ionization constant.

Charles T.

Numerade Educator

Place the following acids in order of increasing strength:

\begin{equation}

\begin{array}{l}{\text { a. valeric acid, } K_{a}=1.5 \times 10^{-5}} \\ {\text { b. glutaric acid, } K_{a}=3.4 \times 10^{-4}} \\ {\text { c. hypoobromous acid, } K_{a}=2.5 \times 10^{-9}} \\ {\text { d. acetylsalicylic acid (aspirin), }} \\ {K_{a}=3.3 \times 10^{-4}}\end{array}

\end{equation}

Teesta D.

University of Pittsburgh - Main Campus

What are the components of a buffer solution? Give an example.

Charles T.

Numerade Educator

If the hydronium ion concentration of a solution is $1.63 \times 10^{-8} \mathrm{M},$ what is the hydroxide ion concentration?

Teesta D.

University of Pittsburgh - Main Campus

Calculate the hydronium ion concentration in a solution of 0.365 $\mathrm{mol} / \mathrm{L}$ of $\mathrm{NaOH} .$

Charles T.

Numerade Educator

How much $\mathrm{HCl}$ would you need to dissolve in 1.0 $\mathrm{L}$ of water so that $\left[\mathrm{OH}^{-}\right]=$ $6.0 \times 10^{-12} \mathrm{M} ?$

Teesta D.

University of Pittsburgh - Main Campus

The hydronium ion concentration in a solution is $1.87 \times 10^{-3}$ mol/L. What is $\left[\mathrm{OH}^{-}\right]$ ?

Charles T.

Numerade Educator

If 0.150 mol of $\mathrm{KOH}$ is dissolved in 500 $\mathrm{mL}$ of water, what are $\left[\mathrm{OH}^{-}\right]$ and $\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]$ ?

Teesta D.

University of Pittsburgh - Main Campus

If a solution contains twice the concentration of hydronium ions as hydroxide ions, what is the hydronium ion concentration?

Charles T.

Numerade Educator

Stomach acid contains $\mathrm{HCl}$ , whose concentration is about 0.03 $\mathrm{mol} / \mathrm{L} .$ What is the pH of stomach acid?

Teesta D.

University of Pittsburgh - Main Campus

If $\left[\mathrm{OH}^{-}\right]$ of an aqueous solution is $0.0134 \mathrm{mol} / \mathrm{L},$ what is the pH?

Charles T.

Numerade Educator

What is the pH of a 0.15 $\mathrm{M}$ solution of $\mathrm{HClO}_{4}, \mathrm{a}$ strong acid?

Teesta D.

University of Pittsburgh - Main Campus

LiOH is a strong base. What is the pH of a 0.082 M LiOH solution?

Charles T.

Numerade Educator

Find the $\mathrm{pH}$ of a solution consisting of 0.29 mol of $\mathrm{HBr}$ in 1.0 $\mathrm{L}$ of water.

Teesta D.

University of Pittsburgh - Main Campus

What is the $\mathrm{pH}$ of aqueous solutions of the strong acid $\mathrm{HNO}_{3},$ nitric acid, if the concentrations of the solutions are as follows: (a) $0.005 \mathrm{M},(\mathrm{b}) 0.05 \mathrm{M},(\mathrm{c}) 0.5 \mathrm{M},(\mathrm{d}) 5 \mathrm{M} ?$

Charles T.

Numerade Educator

Find the $\mathrm{pH}$ of a solution prepared by dissolving 0.65 $\mathrm{mol}$ of the strong base $\mathrm{NaOH}$ in 1.0 $\mathrm{L}$ of water.

Teesta D.

University of Pittsburgh - Main Campus

What is the $\mathrm{pH}$ of a solution prepared by dissolving 0.15 $\mathrm{mol}$ of the strong base $\mathrm{Ba}(\mathrm{OH})_{2}$ in one liter of water? (Hint: How much hydroxide ion does barium hydroxide generate per mole in solution?)

Charles T.

Numerade Educator

A solution has a hydronium ion concentration of $1.0 \times 10^{-9} \mathrm{M} .$ What is its pH?

Teesta D.

University of Pittsburgh - Main Campus

If a solution has a hydronium ion concentration of $6.7 \times 10^{-1} \mathrm{M},$ what is its pH?

Charles T.

Numerade Educator

What is the $\mathrm{pH}$ of a solution whose hydronium ion concentration is $2.2 \times 10^{-12} \mathrm{M} ?$

Teesta D.

University of Pittsburgh - Main Campus

What is the pH of a solution whose $\mathrm{H}_{3} \mathrm{O}^{+}$ concentration is $1.9 \times 10^{-6} \mathrm{M} ?$

Charles T.

Numerade Educator

Calculate the $\mathrm{pH}$ of a 0.0316 $\mathrm{M}$ solution of the strong base RbOH.

Teesta D.

University of Pittsburgh - Main Campus

The pH of a solution is $9.5 .$ What is $\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]$ ? What is $\left[\mathrm{OH}^{-}\right] ?$

Charles T.

Numerade Educator

A solution of a weak acid has a pH of $4.7 .$ What is the hydronium ion concentration?

Teesta D.

University of Pittsburgh - Main Campus

A 50 $\mathrm{mL}$ sample of apple juice has a pH of $3.2 .$ What amount, in moles, of $\mathrm{H}_{3} \mathrm{O}^{+}$ is present?

Charles T.

Numerade Educator

Find $\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]$ in a solution of $\mathrm{pH} 4$.

Teesta D.

University of Pittsburgh - Main Campus

What is the hydroxide ion concentration in a solution of $\mathrm{pH} 8.72 ?$

Charles T.

Numerade Educator

Calculate the concentration of the $\mathrm{H}_{3} \mathrm{O}^{+}$ and $\mathrm{OH}^{-}$ ions in an aqueous solution of pH $5.0 .$

Teesta D.

University of Pittsburgh - Main Campus

A solution has a pH of $10.1 .$ Calculate the hydronium ion concentration and the hydroxide ion concentration.

Charles T.

Numerade Educator

What is the hydronium ion concentration in a solution of pH 5.5?

Teesta D.

University of Pittsburgh - Main Campus

If the pH of a solution is $4.3,$ what is the hydroxide ion concentration?

Charles T.

Numerade Educator

What is the hydronium ion concentration in a solution whose pH is 10.0$?$

Teesta D.

University of Pittsburgh - Main Campus

The pH of a solution is $3.0 .$ What is $\left[\mathrm{H}_{3} \mathrm{O}^{+}\right] ?$

Charles T.

Numerade Educator

What is $\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]$ in a solution whose pH is 1.9$?$

Teesta D.

University of Pittsburgh - Main Campus

If a solution has a pH of 13.3, what is its hydronium ion concentration?

Charles T.

Numerade Educator

To what volumetric mark should a buret be filled?

Teesta D.

University of Pittsburgh - Main Campus

Why is it important to slow down the drop rate of the buret near the end of a titration?

Charles T.

Numerade Educator

What two buret readings need to be recorded in order to determine the volume of solution dispensed by the buret?

Teesta D.

University of Pittsburgh - Main Campus

What volume of 0.100 $\mathrm{M} \mathrm{NaOH}$ is required to neutralize 25.00 $\mathrm{mL}$ of 0.110 $\mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4} ?$

Charles T.

Numerade Educator

What volume of 0.100 $\mathrm{M} \mathrm{NaOH}$ is required to neutralize 25.00 $\mathrm{mL}$ of 0.150 $\mathrm{M} \mathrm{HCl}$ ?

Teesta D.

University of Pittsburgh - Main Campus

If 35.40 $\mathrm{mL}$ of 1.000 $\mathrm{M} \mathrm{HCl}$ is neutralized by 67.30 mL of NaOH, what is the molarity of the NaOH solution?

Charles T.

Numerade Educator

If 50.00 $\mathrm{mL}$ of 1.000 $\mathrm{M} \mathrm{HI}$ is neutralized by 35.41 $\mathrm{mL}$ of $\mathrm{KOH}$ , what is the molarity of the $\mathrm{KOH}$ solution?

Teesta D.

University of Pittsburgh - Main Campus

If 133.73 $\mathrm{mL}$ of a standard solution of $\mathrm{KOH}$ , of concentration $0.298 \mathrm{M},$ exactly neutralized 50.0 $\mathrm{mL}$ of an acidic solution, what was the acid concentration?

Charles T.

Numerade Educator

To standardize a hydrochloric acid solution, it was used as titrant with a solid sample of sodium hydrogen carbonate, NaHCO $_{3} .$ The sample had a mass of $0.3967 \mathrm{g},$ and 41.77 $\mathrm{mL}$ of acid was required to reach the equivalence point. Calculate the concentration of

the standard solution.

Teesta D.

University of Pittsburgh - Main Campus

The graph above shows a titration curve obtained during the titration of a 25.00 $\mathrm{mL}$ sample of an acid with 0.1000 $\mathrm{M} \mathrm{NaOH} .$ Calculate the concentration of the acid.

Charles T.

Numerade Educator

An HNO $_{3}$ solution has a pH of $3.06 .$ What volume of 0.015 $\mathrm{M}$ LiOH will be required to titrate 65.0 $\mathrm{mL}$ of the HNO $_{3}$ solution to reach the equivalence point?

Teesta D.

University of Pittsburgh - Main Campus

The hydronium ion concentration in a 0.100 M solution of formic acid is 0.0043 $\mathrm{M}$ . Calculate $K_{a}$ for formic acid.

Charles T.

Numerade Educator

$\left[\mathrm{NO}_{2}^{-}\right]=9.1 \times 10^{-3} \mathrm{mol} / \mathrm{L}$ in a nitrous acid

solution of concentration 0.123 $\mathrm{mol} / \mathrm{L}$ What is $K_{a}$ for $\mathrm{HNO}_{2}$ ?

Teesta D.

University of Pittsburgh - Main Campus

A solution of acetic acid had the following solute concentrations: $\left[\mathrm{CH}_{3} \mathrm{COOH}\right]=$ $0.035 \mathrm{M},\left[\mathrm{H}_{3} \mathrm{O}^{+}\right]=7.4 \times 10^{-4} \mathrm{M},$ and $\left[\mathrm{CH}_{3} \mathrm{COO}^{-}\right]=7.4 \times 10^{-4} \mathrm{M} .$ Calculate the $K_{a}$ of acetic acid based on these data.

Charles T.

Numerade Educator

Hydrazoic acid, HN $_{3},$ is a weak acid. A 0.01 M solution of hydrazoic acid contained a concentration of 0.0005 $\mathrm{M}$ of the $\mathrm{N}_{3}^{-}$ ion. Find the acid-ionization constant of hydrazoic acid.

Teesta D.

University of Pittsburgh - Main Campus

If 25 $\mathrm{mL}$ of 1.00 $\mathrm{M} \mathrm{HCl}$ is mixed with 75 $\mathrm{mL}$ of $1.00 \mathrm{M} \mathrm{NaOH},$ what are the final amounts and concentrations of all ions present?

Charles T.

Numerade Educator

When 1.0 $\mathrm{mol}$ of a weak acid was dissolved in 10.0 L of water, the pH was found to be $3.90 .$ What is $K_{a}$ for the acid?

Teesta D.

University of Pittsburgh - Main Campus

At the end point of a titration of 25 $\mathrm{mL}$ of 0.300 $\mathrm{M} \mathrm{NaOH}$ with $0.200 \mathrm{M} \mathrm{HNO}_{3},$ what would the concentration of sodium nitrate in the titration flask be?

Charles T.

Numerade Educator

Make a table listing the ionic concentrations in solutions of the following pH values: $14.25,14.00,13.75,13.25,13.00,7.25,7.00$ $6.75,1.00,0.75,0.50,0.25,0.00,$ and $-0.25$

Teesta D.

University of Pittsburgh - Main Campus

Write the equilibrium equation and the equilibrium constant expression for an ammonia-ammonium ion buffer solution.

Charles T.

Numerade Educator

If 18.5 $\mathrm{mL}$ of a 0.0350 $\mathrm{M} \mathrm{H}_{2} \mathrm{SO}_{4}$ solution neutralizes 12.5 $\mathrm{mL}$ of aqueous LiOH, what mass of LiOH was used to make 1.00 $\mathrm{L}$ of the LiOH solution?

Teesta D.

University of Pittsburgh - Main Campus

Use Table 7 to calculate the pH of a buffer solution made from equal amounts of sodium monohydrogen phosphate and potassium dihydrogen phosphate.

Charles T.

Numerade Educator

Why is a buret, rather than a graduated cylinder, used in titrations?

Teesta D.

University of Pittsburgh - Main Campus

A small volume of indicator solution is usually added to the titration flask right before the titration. As a result, the sample is diluted slightly. Does this matter? Why or why not?

Charles T.

Numerade Educator

A student passes an end point in a titration. Is it possible to add an additional measured amount of the unknown and continue the titration? Explain how this process might work. How would the answer for the calculation of the molar concentration of the unknown differ from the answer the student would have gotten if the titration had been performed properly?

Teesta D.

University of Pittsburgh - Main Campus

Refer to the table above to answer the following questions:

\begin{equation}

\begin{array}{l}{\text { a. Which indicator would be the best choice }} \\ {\text { for a titration with an end point at a pH }} \\ {\text { of } 4.0 ?} \\ {\text { b. Which indicators would work best for a }} \\ {\quad \text { titration of a weak base with a strong acid? }}\end{array}

\end{equation}

Charles T.

Numerade Educator

Why does an indicator need to be a weak acid or a weak base?

Teesta D.

University of Pittsburgh - Main Campus

Explain the difference between end point and equivalence point. Why is it important that both occur at approximately the same pH in a titration?

Charles T.

Numerade Educator

Can you neutralize a strong acid solution by adding an equal volume of a weak base having the same molarity as the acid? Support your position.

Teesta D.

University of Pittsburgh - Main Campus

In the 18 th century, Antoine Lavoisier experimented with oxides such as $\mathrm{CO}_{2}$ and

$\mathrm{SO}_{2} .$ He observed that they formed acidic solutions. His observations led him to infer that for a substance to exhibit acidic behavior, it must contain oxygen. However, today that is known to be incorrect. Provide evidence to refute Lavoisier's conclusion.

Charles T.

Numerade Educator

Design an experiment to test the neutralization effectiveness of various brands of antacid. Show your procedure, including all safety procedures and cautions, to your teacher for approval. If your teacher approves your plan, carry it out. After experimenting, write an advertisement for the antacid you judge to be the most effective. Cite data from your experiments as part of your advertising claims.

Teesta D.

University of Pittsburgh - Main Campus

Describe how you would prepare one or more buffer solutions, including which compounds to use. Predict the pH of each solution. If your teacher provides the needed materials, measure the pH to test

your prediction.

Check back soon!

Use the following terms to create a concept map: hydronium ions $\left(H_{3} O^{+}\right),$ hydroxide

ions $\left(O H^{-}\right)$ , neutralization reaction, pH, and titration.

Teesta D.

University of Pittsburgh - Main Campus

What is the $\mathrm{pH}$ at the beginning of the titration?

Teesta D.

University of Pittsburgh - Main Campus

What was the $\mathrm{pH}$ after 25 $\mathrm{mL}$ of titrant had been added?

Charles T.

Numerade Educator

What volume of titrant was needed to reach a pH of 2.0$?$

Teesta D.

University of Pittsburgh - Main Campus

Where on the graph do you find the single most important data point?

Charles T.

Numerade Educator

If the titration continued beyond what the graph shows, how would you expect the pH to change past the end of the graph?

Teesta D.

University of Pittsburgh - Main Campus

Roughly sketch the titration curve $(\mathrm{pH}$ versus volume) that you would expect if you titrated a weak base with a strong acid. Mark the equivalence point.

Charles T.

Numerade Educator

Graphing Calculator

Graphing Titration Data The graphing calculator can run a program that graphs data such as pH versus volume of base. Graphing the titration data will allow you to determine which combination of acid and base is represented by the shape of the graph.

Go to Appendix C. If you are using a TI-83 Plus, you can download the program and data and run the application as directed. Press the APPS key on your calculator, then choose the application CHEMAPS. Press 5 , then highlight ALL on the screen, press 1 , then highlight LOAD and press 2 to load the data into your calculator. Quit the application, and then run the program TITRATN. For $\mathrm{L}_{1},$ press 2 $\mathrm{nd}$ and $\mathrm{LIST},$ and choose VOL 1. For $\mathrm{L}_{2},$ press 2 nd and LIST and choose PH1. If you are using another calculator, your

teacher will provide you with keystrokes and data sets to use.

\begin{equation}

\begin{array}{l}{\text { a. At what approximate volume does the }} \\ {\text { pH change from acidic to basic? }} \\ {\text { b. If the titrant was } 0.24 \mathrm{M} \mathrm{NaOH} \text { , and the }} \\ {\text { volume of unknown was } 230 \mathrm{mL}, \text { what }} \\ {\text { was }\left[\mathrm{H}_{3} \mathrm{O}^{+}\right] \text { in the unknown solution? }}\end{array}

\end{equation}

Check back soon!