In a constant‑pressure calorimeter, 55.0 mL of 0.820 M H 2 SO 4 was added to 55.0 mL of 0.360 M NaOH . The reaction caused the temperature of the solution to rise from 23.45 ∘ C to 25.90 ∘ C. If the solution has the same density and specific heat as water ( 1.00 g / mL and 4.184 J / ( g ⋅ °C), respectively), what is Δ H for this reaction (per mole of H 2 O produced)? Assume that the total volume is the sum of the individual volumes.
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The spacing between absorption lines in the far infrared spectrum of H35Cl is 6.350 x 1011Hz. Assuming the Rigid Rotor Model, calculate the values of the moment of inertia and the bond length in H35Cl.
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Just as pH is the negative logarithm of [H3O+], pKa is the
negative logarithm of Ka,
pKa=−logKa The Henderson-Hasselbalch equation is used to calculate the pH of buffer solutions:pH=pKa+log[base][acid] Notice that the pH of a buffer has a value close to the pKa of the acid, differing only by the logarithm of the concentration ratio [base]/[acid]. The Henderson-Hasselbalch equation in terms of pOH and pKb is similar.pOH=pKb+log[acid][base] |
Part A Acetic acid has a Ka of 1.8×10−5. Three acetic acid/acetate buffer solutions, A, B, and C, were made using varying concentrations:[acetic acid] ten times greater than [acetate], [acetate] ten times greater than [acetic acid], and [acetate]=[acetic acid]. Match each buffer to the expected pH. Drag the appropriate items to their respective bins. SubmitHintsMy AnswersGive UpReview Part Correct Part B How many grams of dry NH4Cl need to be added to 1.50 L of a 0.400 M solution of ammonia, NH3, to prepare a buffer solution that has a pH of 8.57? Kb for ammonia is 1.8×10−5. Express your answer with the appropriate units.
SubmitHintsMy AnswersGive UpReview Part Incorrect; Try Again; 5 attempts remaining PLEASE HELP ME ANSWER PART B |
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Given the molality of isoborneol is 0.701 mol/kg, what is the percent by mass of camphor in the product?
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The heat of fusion of ice is 6.00 kJ/mol. Find the number of photons of wavelength = 6.27 10-6 m that must be absorbed to melt 3.00 g of ice.
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what is the pH of a solution that mixes 30.00 mL of 0.010 M Ch3oh with 30.00 mL 0.00750 M Nach3co2?
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The triple point of ammonia is at 196.2 K and 49.42 torr. The
molar enthalpy change of vaporization is equal to 24.65 kJ
mol-1 at this temperature.
a. Find the normal boiling temperature of ammonia.
b. The actual boiling temperature is -33 ̊C. Find the average value
of the molar enthalpy change of vaporization for the range between
the triple point and the normal boiling temperature.
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1. Which of the following alkyl halides would not be suitable to make a Wittig reagent
1-bromo-2-methylpropane
2-bromobutane
2-bromo-2-methylpropane
(Bromomethyl)cyclopentane
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a) What is the pH of a buffer solution prepared by mixing 120 mL of a 0.435 M CH3CO2H with 50 mL of a .286 M CH3CO2Na solution? CH3CO2H Ka = 1.75 x 10-5
b) What is the resulting pH if we add 10.2 mL of a .513 M HCl solution to this buffer? Does the pH make sense? Why/why not?
c) What is the resulting pH if we add 3.56 mL of a 0.420 M NaOH solution to the original buffer?
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Calculate the pH at 25 C of a 0.75 M aqueous solution of phosphoric acid (H3PO4). (Ka1, Ka2, and Ka3 for phosphoric acid are 7.5*10-3, 6.25*10-8, and 4.8*10-13, respectively.)
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± Introduction to Solubility and the Solubility Product Constant Learning Goal: To learn how to calculate the solubility from Kspand vice versa. Consider the following equilibrium between a solid salt and its dissolved form (ions) in a saturated solution:CaF2(s)⇌Ca2+(aq)+2F−(aq) At equilibrium, the ion concentrations remain constant because the rate of dissolution of solid CaF2 equals the rate of the ion crystallization. The equilibrium constant for the dissolution reaction isKsp=[Ca2+][F−]2 Ksp is called the solubility product and can be determined experimentally by measuring thesolubility, which is the amount of compound that dissolves per unit volume of saturated solution. |
Part A A saturated solution of lead(II) chloride, PbCl2, was prepared by dissolving solid PbCl2 in water. The concentration of Pb2+ ion in the solution was found to be 1.62×10−2M . Calculate Ksp for PbCl2. Express your answer numerically.
SubmitHintsMy AnswersGive UpReview Part Part B The value of Ksp for silver sulfide, Ag2S, is 8.00×10−51. Calculate the solubility of Ag2S in grams per liter. Express your answer numerically in grams per liter. |
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1. On page 410 in your Brown & Foote textbook, the following reaction is shown.
3-pentanol + HBr --heat--> 3-bromo-pentane (major product) + 4-bromo-pentane (minor product)
a. Explain how the minor product can form in this reaction and what does it tell us about the mechanism by which the reaction proceeded.
b. Is there any basis in reality to the books claim regarding this reaction? Perform a literature search to see if indeed any chemist reported such results. If you do find such a paper, give the full citation of the paper.
2. Part of the procedure this week calls for a reflux which has a water cooled condenser open on the top to the atmosphere. Why would it be a bad idea to stopper or cap the apparatus? Explain what would happen if the apparatus was capped?
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A 1.00 mL ampule of a 0.150 M solution of naphthalene in hexane is excited with a flash of light. The naphthalene emits 12.5 J of energy at an average wavelength of 349 nm. What percentage of the naphthalene molecules emitted a photon?
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