Bridging the Gap 1 Name Acidity, pH, Indicator Paper and Red Cabbage Data and Observations Household substance Cabbage juice indicator color Estimated 1--1 pH using a e 266 Analysis and Conclusions Do you believe the estimated experimental pH values and the table values agree? Remember these are only estimates and are not exact. Justify your answer.
Bridging the Gap 1 Name Acidity, pH, Indicator Paper and Red Cabbage Data and Observations Household substance Cabbage juice indicator color Estimated 1--1 pH using a e 266 Analysis and Conclusions Do you believe the estimated experimental pH values and the table values agree? Remember these are only estimates and are not exact. Justify your answer.
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Related questions
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 âdraw.â
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: thereâs one for each line provided below.
|
a. NaHCO3 Ã 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 Ã 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 Ã 2H2O + Na2SO4
F. Define the term âneutralizationâ and provide an example of a neutralization equation. List the three ways used in this lab to detected neutralization.
G. Define the term âsalt,â 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?
1.) average number of moles of NaOH dispensed |
---|
2.)average concentration of the acid (mol/L) |
---|
3,) Based on your coarse titration volume, do you expect the acetic acid solution to have a higher or lower concentration than the NaOH solution?
higher could you please tell me if number 3 is right |
please help with these 2 questions
Part 1: Prepare the NaOH Solution
Lab Results
How many mL of water were used to prepare the NaOH solution?
200mL |
Data Analysis
Calculate the molarity of the NaOH solution. The molar mass of NaOH is 39.997 g/mol.
0.1M |
Calculate the amount of benzoic acid to be neutralized by 20.00 mL NaOH solution, in both moles and grams. The molar mass of benzoic acid is 122.12 g/mol.
1.207 g |
Part 2: Perform a Coarse Titration
Lab Results
Record the following data from your course titration in the table below.
mass of benzoic acid used (g) | 0.26614g |
---|---|
pH of benzoic acid solution before titration | 2.96 |
volume of NaOH in the burette before titration (mL) | 50.0mL |
volume of NaOH in the burette after titration (mL) | 28.89mL |
volume of NaOH dispensed in the titration (mL) | 21.11mL |
Data Analysis
How do you expect your coarse titration volume to compare to your fine titration volumes?
I expect the values to be a little off from each other since in the first titration we let out a lot at a time and didnt slowly do the titration. should only be off by a few mL. |
Part 3: Perform Fine Titrations
Lab Results
Record the volume of NaOH solution dispensed in the 3 fine titrations.
20 mL dispenced ,20.34mL, 20.30mL |
Data Analysis
Calculate the average concentration of the NaOH solution, using the average volume of NaOH solution dispensed in the 3 fine titrations. Report your answer using enough significant figures to distinguish it from the expected concentration of 0.100 M.
V = (V1 + V2 + V3) / 3 V = (20.03 mL + 20.06 mL + 20.02 mL) / 3 = 20.04 mL M = n / V = 0.00200 moles / 0.02004 L = 0.0998 M Learning objective: Determine the concentration of a solution. 20.21= ----> 0.0999M |
Experiment 2: Use the Standardized NaOH Solution to Determine the Concentration of an Acid
Part 1: Perform a Coarse Titration
Lab Results
What was the pH at the end point of the coarse titration?
3.87ph |
Data Analysis
Based on your coarse titration volume, do you expect the acetic acid solution to have a higher or lower concentration than the NaOH solution?
higher |
Part 2: Perform Fine Titrations
Lab Results
For the 3 fine titrations of the acid of unknown concentration, fill in the following data.
Titration #1 | Titration #2 | Titration #3 | |
---|---|---|---|
volume of acid (mL) | 59.11 | 40.97 | 40.98 |
volume of NaOH dispensed (mL) | 9.05 | 9.03 | 9.02 |
Data Analysis
Calculate the following quantities and record the data in the table below.
average volume of NaOH solution dispensed (mL) | 9.03 |
---|---|
average number of moles of NaOH dispensed | |
average concentration of the acid (mol/L) |
Conclusions
Phenolphthalein is pink over the range of pH 8 â 12. Why was it a useful indicator of when the equivalence point was reached?
This was helpful because once I got to the ph of 7 I knew that I would be getting closer to the end point which would change the color to pink. |
Suppose a student titrated a sample of monoprotic acid of unknown concentration using a previously standardized solution of NaOH.
volume of 0.125 M NaOH dispensed | 24.68 mL |
---|---|
volume of acid solution | 50.00 mL |
Given the data in the figure above, what is the concentration of the unknown acid?
0.0617M Lab NOTES: ex1 Take sodium hydroxide from the Materials shelf and add 0.800 g to the beaker. Take water from the Materials shelf and add 200 mL to the beaker. Ph 2.96 inital volume in burett inital volume 50ml 1.) volume43.78mL volumes dispenced =6.22ml 2. volume =38.05 volume dispenced =11.95ml 3.)volume = 32.06 volume dispenced=17.94 4.28.89ml volume dispenced=21.11ml ph=10.95 -------------------------------------- Ex 2 inital ph= 2.96 volume30.33 dispence 20.05 1. volume 39.92ml volume dispenced=10.08 2.volume 29.66 voiume dispence 20.34 final ph10.43 initial valume in burett 50ml -------------------- ex3 final ph9.43 volume 30.28 volume dipenced=20.00 ---------------------------------------------------------------------- 2nd Ex initial ph 3.11 volume 50 1. volume 48.95mL dispenced 1.05mL ph 3.87 2. volume 45.88 dispenced 4.12 ph 4.67 3 volume 42.99 dispenced 7.01 ph 5.29 4 volume 39.93 dispence 10.07 ph 11.45 -------------------- F1 final ph 9.99 volume 59.11 dispenced 9.05 F2 ph 9.59 volume 40.97 dispenced 9.03 f3 ph 9.50 volume 40.98 9.02 |