When creating a titration curve for a weak base, the pH of the initial solution requires setting up a table showing the initial, change, and equilibrium values for each species and plugging these into the equilibrium constant expression. The expression for the bicarbonate ion is Ka1=[H2CO3][H+][HCO3−] For an anion that can both hydrolyze and produce H+, the pH of a concentrated solution can be more easily approximated using the equation pH=12(pKa1+pKa2) During the titration before the equivalence point, provided that the concentration of acid is significantly more than the concentration of base, the Henderson-Hasselbalch equation can be used to approximate the pH: pH=pKa+log[base][acid] At the equivalence point, the solution is no longer a buffer, but contains the weak acid H2CO3. The change in concentration of the bicarbonate ion is significant, and the equilibrium constant expression for Ka1 must again be used to find the concentration of hydronium ions. After the equivalence point, the strong acid will control the pH.
Part A
A 10.0-mL sample of 1.0 M NaHCO3 is titrated with 1.0 M HCl (hydrochloric acid). Approximate the titration curve by plotting the following points: pH after 0 mL HCl added, pH after 1.0 mL HCl added, pH after 9.5 mL HCl added, pH after 10.0 mL HCl added (equivalence point), pH after 10.5 mL HCl added, and pH after 12.0 mL HCl added.
In: Chemistry
Part A
Calculate the change in pH that results from adding 0.190 mol NaNO2 to 1.00 L of 0.190 M HNO2(aq). (Ka(HNO2)=7.2⋅10−4) Express your answer using two decimal places.
Part B
Calculate the change in pH that results from adding 0.190 NaNO3 to 1.00 L of 0.190 HNO3(aq). Express your answer using two decimal places.
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A sample of 7.70 L of NH3 (ammonia) gas at 22 ∘C and 735 torr is bubbled into a 0.400 L solution of 0.400 M HCl (hydrochloric acid). The Kb value for NH3 is 1.8×10−5.
Assuming all the NH3 dissolves and that the volume of the solution remains at 0.400 L , calculate the pH of the resulting solution. Express your answer numerically to two decimal places.
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Assume you dissolve 0.235 g of the weak acid benzoic acid, C6H5CO2H, in enough water to make 3.00 ✕ 102 mL of solution and then titrate the solution with 0.133 M NaOH. C6H5CO2H(aq) + OH-(aq) C6H5CO2-(aq) + H2O(ℓ) What are the concentrations of the following ions at the equivalence point? Na+, H3O+, OH- C6H5CO2- Incorrect: Your answer is incorrect. M Na+ Incorrect: Your answer is incorrect. M H3O+ Incorrect: Your answer is incorrect. M OH- Incorrect: Your answer is incorrect. M C6H5CO2- What is the pH of the solution? Incorrect: Your answer is incorrect.
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Rank the following atoms in the order of decreasing electron affinity. Li, Si, Mg, S
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Suppose a 500.mL flask is filled with 1.5mol of CO , 0.60mol of H2O and 1.8mol of CO2 . The following reaction becomes possible: +COgH2Og +CO2gH2g The equilibrium constant K for this reaction is 3.35 at the temperature of the flask. Calculate the equilibrium molarity of H2 . Round your answer to one decimal place.
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What is the percent dissociation of HX (pKa = 4.30) in a 0.380 M solution?
________ %
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Calculate the pH of 100.0 mL of a buffer that is 0.050 M NH4Cl and 0.180 M NH3 before and after the addition of 1.00 mL of 5.70 M HNO3.
Before =
After=
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about this time you may be wishing you had an aspirin. Aspirin is an organic acid with a ka of 3.27E-4 for the reaction HC9H7O4(aq) +H2O(L) <--> C9H7O4-(aq) +H3O+(aq) If you have two tablets each containing 0.325g of asprin (mixed with a neutral "binder" to hold the tablet together), and you dissolve them in a glass of water to give 225ml of solution, what is the ph of the solution?
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Calculate the change in pH when 0.28 mol H+ is added to 1.00 L of each of the following buffers:
(a) A 0.58 M solution of pyridine (py) containing 0.52 M pyH+
(b) A 0.60 M solution of aniline (an) containing 0.92 M anH+
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Calculate the PH of 1.00 L of a buffer that is 0.130 M HNO2 and 0.170 M NaNO2. What is the PH of the same buffer after the addition of 1.00 mL of 12.0 M HCl. (pKa of HNO2 = 3.40).
Original Buffer:
After HCl is added:
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Which of the following correctly characterizes the reactivity and/or use of free radicals?
Free radicals are used in the conversion of liquid resins into solid plastics.
Free radicals are generally stable molecules found in the human body.
Free radicals are essential to repair damaged DNA in the human body.
Reaction of free radicals with other materials often leads to color staining on those materials.
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consider the following reaction at equilibrium: 4 NH3 + 5 O2 <---> 4 NO + 6 H2O. What would happen to the position of the equilibrium if:
a) more oxygen is added
b) the pressure was increased
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TLC (thin layer chromatography), how does it work? How would changing the stationary vs mobile phase effect the movement of molecules?
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How do I calculate the inicial concentration of I^- and S2O8^2- in each mixture, the reaction rate M/s, and the k value (rate constant) from the following data???? IODINE CLOCK REACTION
| Run # | 3% Starch | 0.012 M Na2S2O3 mL | 0.20 M KI mL | 0.20 M KNO3 mL | 0.20 M (NH4)2SO4 mL | 0.20 M (NH4)2S2O8 mL | Total mL |
| 1 | 2 drops | 0.200 | 0.800 | 0.200 | 0.400 | 2.00 | |
| 2 | 2 drops | 0.200 | 0.400 | 0.600 | 0.400 | 2.00 | |
| 3 | 2 drops | 0.200 | 0.200 | 0.800 | 0.400 | 2.00 | |
| 4 | 2 drops | 0.200 | 0.400 | 0.600 | 0.00 | 2.00 | |
| 5 | 2 drops | 0.200 | 0.400 | 0.600 | 0.600 | 2.00 |
Run#1-time was 41.45 sec Run#2-time was 120.48 sec Run#3-231.64 sec Run#4-36.88 sec Run#5-231.70 sec
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