Acid Base Solutions and pH Scale

ACID BASE SOLUTIONS and PH scale 

Lab 3: Acid/Base Discovery Activity

Background: Acids and bases are responsible for a very unique type of reaction called, conveniently enough, acid-base reactions. In this lab, you will continue to investigate pH Scales and Acid-Base solutions using two online demos. Answer the questions carefully. Then save this file with your name and submit it on Blackboard in the Lab 3: Acid Basefolder.

Part I: Exploring pH Scales.

For this activity, you will explore aspects of pH using the “pH Scale” online demo available through Blackboard and at the link below. Before you begin, familiarize yourself with the program’s controls, practicing with the click-and-drag sliders and the drop-down menus. When you have finished exploring the program, press Reset All. Then answer the following questions by manipulating the variables as specified.

Lab Link: http://phet.colorado.edu/en/simulation/ph-scale

A. Check the box entitled “H₃O⁺/OH^-ratio.” Red dots represent hydronium ions while blue dots represent hydroxide ions. Adjust the pH slider up and down, observing how this changes the number of each type of ion.

1. As you raise pH, which type of ion concentration increases? Click here to enter text.

2. As you lower pH, which type of ion concentration increases? Click here to enter text

3. Based on your observations, what does a high (greater than 7) pH indicate?

Click here to enter text.

4. What does a low (lower than 7) pH indicate?

Click here to enter text.

B. Reset the simulation.Check the box entitled “Molecule Count.”

1. From the drop down menu in the top right, select “vomit” (pH 2.0) and record the number of hydronium ions. Click here to enter text.

2. Then, select “battery acid” (pH 1.0) and record the number of hydronium ions. Click here to enter text.

3. Determine how many times more concentrated battery acid is than vomit. To do this, divide the number of hydronium ions in battery acid by the number of hydronium ions in vomit (use a calculator):

Battery acid is Click here to enter text times more concentrated than vomit.

C. Reset the simulation. Check the box entitled “Molecule Count.”

1. From the drop down menu, select “drain cleaner” (pH 13.0) and record the number of hydroxide ions. Click here to enter text

2. Then, select “hand soap” (pH 10.0) and record the number of hydroxide ions.
Click here to enter text.

3. Determine how many times more concentrated drain cleaner is than hand soap. In this case, you are dealing with basic solutions. Adjust your calculations accordingly.

Drain cleaner is Click here to enter text. times more concentrated than hand soap.

Part II: Strong and Weak Acids.

Directions: For this activity, you will explore acid-base solutions using the “Acid-Base Solutions” online demo available through Blackboard and at the link below. Before you begin, familiarize yourself with the program’s controls, practicing with the click-and-drag sliders and the drop-down menus. When you have finished exploring the program, press Reset All. Then answer the following questions by manipulating the variables as specified.

Lab Link: http://phet.colorado.edu/en/simulation/acid-base-solutions

A. Note that the key for the acid-base equilibrium is below the reaction container on the screen. Set concentration to “.001 M” by dragging the slider to the left. Set the acid type to maximum weakness by dragging the slider to the left.

1. Describe the equilibrium of this system.What do you notice about the amount of “HA” (unreacted acid) vs. “A^-“ (reacted acid)?

Click here to enter text.

2. Lower the pH meter into the solution by dragging the pH meter’s tip into the solution. What is the pH of the .001 M strong acid? Click here to enter text.

B. Reset the simulation. Set concentration to “.001 M.” Set the acid type to maximum strength by dragging the slider to the right.

1. Describe the equilibrium of this system. What do you notice about the amount of “HA” (unreacted acid) vs. “A^-” (reacted acid)?

Click here to enter text.

2. Lower the pH meter into the solution by dragging the pH meter’s tip into the solution. What is the pH of the .001 M weak acid? Click here to enter text.

3. Is the conductivity trend of strong and weak bases similar to that of strong and weak acids? Explain why or why not.

Click here to enter text.