Question

Acid/Base Chemistry

Portland Community College Staff*

Version 42-0137-00-01

Lab Report Assistant                                                                                            

This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.

Observations                                                                                                            In columns 3 and 4, record the color and intensity seen. In columns 5 and 6, determine if the substance is an acid or a base, and if the substance is ionic. For the last column, determine which chemical species is acting as an acid or base.

Data Table 1: Acids and Bases Acting in Water
Well	Substance	1drop BTB	Plus 1 drop of substance	Acid or base (Q1)	Ionic? Y/N (Q2)	Species acting as acid or base (Q3)
1	NaHCO3
2	CH3COOH
3	HCL
4	Na2CO3
5	H2SO4
6	CH3COONa
7	NaOH
8	HNO3
9	NaHSO4
10	NH3
11	H3PO4
12	NaH2PO4
13	Na2HPO4
14	Na3PO4
15	NaHSO3

Data Table 2: Following Acid/Base neutralization reactions
Well #	1 Drop of Each	Observation	+2 Drops Acid	Observation	+2 Drops Base	Observation
1	BPB + NaOH		HCl		NaOH
2	BPB + NaOH		H2SO4		NaOH
3	BPB + NaOH		CH3COOH		NaOH
4	BPB + NaOH		H3PO4		NaOH
5	BPB + Ca(OH)2		HCl		Ca(OH)2
6	BPB + Ca(OH)2		H2SO4		Ca(OH)2
7	BPB + Ca(OH)2		CH3COOH		Ca(OH)2
8	BPB + Ca(OH)2		H3PO4		Ca(OH)2
9	BPB + NH3		HCl		NH3
10	BPB + NH3		H2SO4		NH3
11	BPB + NH3		CH3COOH		NH3
12	BPB + NH3		H3PO4		NH3

Please note here if any of the other starting materials is other than a clear, colorless solution.

Data Table 3: Investigating Odor as a Means of Indicating Neutralization.
Substance(s)	Odor
2 Drops of HCl in Well #1
1 Drop of Ammonia on Swab
Swab with Ammonia & HCl

Data Table 4: Investigating Evaporation as a Means of Indicating a Neutralization Reaction.
Reaction Mixture	Observation (When Wet)	Observation (When Dry)
HCl + NaOH
CH3COOH + NH3
HNO3 + NaOH

PART 5: Mini-Experiments

1.   Use BTB to classify four household products as acidic or basic. Possible substances to test include home cleaning products, glass cleaner, liquid detergent, bleach, soft drinks, liquid from food items, etc. Remember to:

a. Hypothesis (What you think will happen and why) or purpose:

b. Method used to test your hypothesis:

c. Data and Observations Put your data and observations in the space below. You can include pictures that you “draw.”

d. Conclusions

2. Find one common, highly colored substance that can be used as an acid-base indicator.

Possible substances include fruit/vegetable juice or products, inks, food coloring, flower

petals, etc. If using fresh fruit, veggies, or flowers, crush the substance with a little water or

rubbing alcohol to extract the colored pigments. If red cabbage is available, it makes a superb

acid-base indicator. Then use a few drops of the colored extract as the indicator. Test four

more household products using the freshly made acid-base indicator. Remember to:

a. State a hypothesis or purpose.

b. State the testing method.

c. Use the prepared indicator to test four substances known to be acids or bases from either the LabPaq or home materials and record results.

d. State conclusions in terms of the hypothesis or purpose.

Questions                                                                                                                   

A. Review the substances used in Part 1. Determine whether each substance contains an acid or a base based on the BTB results. Place answers to this question in column 6 of Data Table 1.

B.   Review the responses to Question 3. The anion that is produced in the dissociation of the compound goes on to react with the water. Identify the anion product in each reaction. Place the formulas for these species into column 7 of Data Table 1. If the substance is not ionic and thus does not dissociate, then list the substance in column 7, just as it appears in column 1.

-

C.   For each ionic species in Data Table 1, write the equation showing the dissociation of the compound in water. Hint: there’s one for each line provided below.

+

a. NaHCO3 à Na

+ HCO3

Review the responses to Question 3. The anion that is produced in the dissociation of the compound goes on to react with the water. Identify the anion product in each reaction. Place the formulas for these species into column 7 of Data Table 1. If the substance is not ionic and thus does not dissociate, then list the substance in column 7, just as it appears in column 1.

D. Write the reaction of each acid or base the substance listed in column 7 with water.

Acids:                                                     Bases:

a) HCO - + H-OH à H CO

+ OH-

3                                           2         3

1. What is produced in each and every reaction of an acid with water?

2. What is produced in each and every reaction of a base with water?

E. Review the results in Data Table 2. For each reaction mixture, write the reaction equation describing the acid/base neutralization reaction:

2) 2NaOH + H2SO4 à 2H2O + Na2SO4

F.    Define the term “neutralization” and provide an example of a neutralization equation. List the three ways used in this lab to detected neutralization.

G. Define the term “salt,” and provide an example.

H. Review Data Table 3. What happened when the two chemicals were mixed? What indicates that conclusion? What reaction took place?

I.    Review Data Table 4. What happened when the solution mixtures on the glass slide were heated? Describe the process that took place.

J.    In Part 4, for HCl + NaOH, what is left on the slide after heating? Provide the formula. What is the common name of this substance?

Answer 1