Question

You need a strong acid for an experiment, and you are given a bottle that you...

You need a strong acid for an experiment, and you are given a bottle that you are told contains a strong acid at 15.0 M concentration. (The name of the acid on the label was rubbed off, so you are not sure of the identity of the acid.) You make a 0.1 M solution and you want to know if you can assume that the [H+] will be 0.1 M since the acid is a strong acid and thus should (so you have been told) completely dissociate. You see that the label on the bottle lists a pKa for the acid of -6.3. A pKa? Why does a strong acid have a pKa? You decide that you better calculate the relative error that will result when you make the assumption that a 0.1 M solution of the strong acid will result in a 0.1 M [H+] versus the concentration that you obtain when you properly treat the dissociation using the listed pKa value. Normally, the relative error is expressed as follows: Er = ((xi – xt)/xt) × 100; where xi is the value under the assumption that complete dissociation occurs and xt is the true or actual value obtained when the pKa of the acid is taken into account. Now, the units for an answer that is expressed as a percent could equivalently be stated as “parts per hundred”. Because the value of ((xi – xt)/xt) is likely to be a small number, I want you to multiply this value by 109rather than 102 (as shown in the above equation). Thus, your answer will be in terms of parts per billion (ppb), and you should report your answer in these terms to the nearest ones (e.g., enter “11” if your answer is 11 ppb). For this problem, you can ignore the contribution of H+ ions due to the autoproteolysis of water. You will need to do this problem with the aid of a spreadsheet, and be sure to adjust the format of the cells to retain several figures beyond the decimal point.

Homework Answers

Answer #1

1. pKa of stong acids means that hydronium ion [H+] concentration in aqeous solution at standard pressure and temp is equal to the strong acid introduced to the solution.

2.pH = -log(0.1) = 1 i.e [H+] = 0.1

3. pKa = -log (Ka) = pH for strong acids as the concentration of [H+] = [A-]

so, pH = pKa = -6.3 = -log(H+)

[H+] = 1995262 at 15 M concentration

At 0.1 M, it would be 1995262/150 = 1330

4. Er = ((xi – xt)/xt) × 100

where,

xi is the value under the assumption that complete dissociation occurs and

xt is the true or actual value obtained when the pKa of the acid is taken into account.

= [(0.1-1330.41)/1330.41] X 1000000000 = - 999924835 ppb

[acid] 0.1M
pH value 1
pKa -6.3
error - 999924835 ppb
Know the answer?
Your Answer:

Post as a guest

Your Name:

What's your source?

Earn Coins

Coins can be redeemed for fabulous gifts.

Not the answer you're looking for?
Ask your own homework help question
Similar Questions
You need a strong acid for an experiment, and you are given a bottle that you...
You need a strong acid for an experiment, and you are given a bottle that you are told contains a strong acid at 15.0 M concentration. (The name of the acid on the label was rubbed off, so you are not sure of the identity of the acid.) You make a 0.1 M solution and you want to know if you can assume that the [H+] will be 0.1 M since the acid is a strong acid and thus should...
You need a strong acid for an experiment, and you are given a bottle that you...
You need a strong acid for an experiment, and you are given a bottle that you are told contains a strong acid at 15.0 M concentration. (The name of the acid on the label was rubbed off, so you are not sure of the identity of the acid.) You make a 0.1 M solution and you want to know if you can assume that the [H+] will be 0.1 M since the acid is a strong acid and thus should...
Hydrochloric acid (HCl) is considered a strong acid. For many problems, it is convenient to assume...
Hydrochloric acid (HCl) is considered a strong acid. For many problems, it is convenient to assume that it completely dissociates to H+ ions and Cl− ions. But how good is this assumption? As a way to find out, calculate the relative error that results when one makes this assumption with a 0.1 M solution of HCl. Report your answer as a percent to one significant figure, and include the proper sign. Recall that relative error (in this context) is as...
To learn how to calculate ion concentrations in an aqueous solution of a strong diprotic acid....
To learn how to calculate ion concentrations in an aqueous solution of a strong diprotic acid. Sulfuric acid, H2SO4, is a strong acid. Its complete dissociation in aqueous solution is represented as H2SO4?H++HSO4? A HSO4? anion can dissociate further by HSO4??H++SO42? but the extent of dissociation is considerably less than 100%. The equilibrium constant for the second dissociation step is expressed as Ka2=[H+][SO42?][HSO4?]=0.012 Part A Calculate the concentration of H+ ions in a 0.010 M aqueous solution of sulfuric acid....
To learn how to calculate ion concentrations in an aqueous solution of a strong diprotic acid....
To learn how to calculate ion concentrations in an aqueous solution of a strong diprotic acid. Sulfuric acid, H2SO4, is a strong acid. Its complete dissociation in aqueous solution is represented as H2SO4?H++HSO4? A HSO4? anion can dissociate further by HSO4??H++SO42? but the extent of dissociation is considerably less than 100%. The equilibrium constant for the second dissociation step is expressed as Ka2=[H+][SO42?][HSO4?]=0.012 Part A Calculate the concentration of H+ ions in a 0.010 M aqueous solution of sulfuric acid....
You want to make 100 mL of 0.20 M Acetic Acid buffer with pH=4.0 You are...
You want to make 100 mL of 0.20 M Acetic Acid buffer with pH=4.0 You are given a stock solution of 1.0 M acetic acid and a bottle of sodium acetate salt (MW= 82 g/mol). The formula for the dissociation of acetic acid is shown here (CH3COOH <--> CH3COO- + H+) The henderson hasselbach equation is : pH=pKa +log [A-]/[HA]. What is the ratio of [A-]/[HA] when your buffer pH is 4.0? Determine the concentration of weak acid and conjugate...
1. The printed label on a bottle of commercial vinegar states that the acetic acid concentration...
1. The printed label on a bottle of commercial vinegar states that the acetic acid concentration is 5%. (Assume % is weight solute/volume solution) (a) If the manufacturer had reported two significant figures in the concentration, what range of values would round to 5.0 %? (b) Calculate the concentration in molarity of the upper and lower values from (a). The molecular weight of acetic acid is 60.05 g/mol. Pay attention to significant figures. 2. Acetic acid is a monoprotic weak...
1. Strong base is dissolved in 565 mL of 0.400 M weak acid (Ka = 3.85...
1. Strong base is dissolved in 565 mL of 0.400 M weak acid (Ka = 3.85 × 10-5) to make a buffer with a pH of 4.07. Assume that the volume remains constant when the base is added. a. Calculate the pKa value of the scid and determine the number of moles of acid initially present. b. When the reaction is complete, what is the concentration ratio of conjugate base to acid? c. How many moles of strong base were...
5. Compare the definition of a weak acid to the definition of a strong acid to...
5. Compare the definition of a weak acid to the definition of a strong acid to explain why the reaction of acetic acid(HC2H3O2) (a weak acid)) with NaoH(a strong base) is less exothermic than the reaction between HCl(a strong acid) and NaoH. 6. A student carries out a calorimetry experiment using HCI and NaoH. What effect will each of the following have on the calculated enthalpy of the reaction relative to the actual enthalpy of reaction? (larger, smaller or no...
1.) You will work with 0.10 M acetic acid and 17 M acetic acid in this...
1.) You will work with 0.10 M acetic acid and 17 M acetic acid in this experiment. What is the relationship between concentration and ionization? Explain the reason for this relationship 2.) Explain hydrolysis, i.e, what types of molecules undergo hydrolysis (be specific) and show equations for reactions of acid, base, and salt hydrolysis not used as examples in the introduction to this experiment 3.) In Part C: Hydrolysis of Salts, you will calibrate the pH probe prior to testing...
ADVERTISEMENT
Need Online Homework Help?

Get Answers For Free
Most questions answered within 1 hours.

Ask a Question
ADVERTISEMENT