At a certain temperature, the equilibrium constant for the following chemical equation is 2.20. At this temperature, calculate the number of moles of NO2(g) that must be added to 2.73 mol of SO2(g) in order to form 1.30 mol of SO3(g) at equilibrium.
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Why does a change in polarizability in a molecule allow a vibrational mode to be Raman active? Why does a change in dipole moment allow a vibrational mode to be IR active? Why do they differ?
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If the Kb of a weak base is 4.1 × 10-6, what is the pH of a 0.50 M solution of this base?
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Aqueous hydrobromic acid HBr reacts with solid sodium hydroxide NaOH to produce aqueous sodium bromide NaBr and liquid water H2O. What is the theoretical yield of water formed from the reaction of 79.3g of hydrobromic acid and 52.9g of sodium hydroxide? Be sure your answer has the correct number of significant digits in it.
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what is the pH of 0.124 M pyridine (C5H5N)?
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A 1.00 L flask is filled with 1.20 g of argon at 25 ∘C. A sample of ethane vapor is added to the same flask until the total pressure is 1.450 atm . What is the partial pressure of argon, PAr, in the flask?
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Find the pH of a solution made by dissolving 0.195 g of phenol (C6H5OH) in enough water to make 125 mL of solution.
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When an ant bites you, the reason it stings is because of an injection of formic acid. What is the pH when 50.00 mL of 0.1480 M formic acid (HCOOH) is titrated with 40.2 mL of 0.1841 M of NaOH? pKa of formic acid = 3.745
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Aqueous hydrobromic acid HBr will react with solid sodium hydroxide NaOH to produce aqueous sodium bromide NaBr and liquid water H2O .
Suppose 60. g of hydrobromic acid is mixed with 48.8 g of sodium
hydroxide. Calculate the minimum mass of hydrobromic acid that
could be left over by the chemical reaction. Be sure your answer
has the correct number of significant digits.
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A 110.0 −mL sample of a solution that is 2.8×10^−3 M in AgNO3 is mixed with a 220.0 −mL sample of a solution that is 0.11 M in NaCN. A complex ion forms. After the solution reaches equilibrium, what concentration of Ag+(aq) remains?
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Titanium occurs in the magnetic mineral ilmenite (FeTiO3), which is often found mixed up with sand. The ilmenite can be separated from the sand with magnets. The titanium can then be extracted from the ilmenite by the following set of reactions: FeTiO3(s)+3Cl2(g)+3C(s)→3CO(g)+FeCl2(s)+TiCl4(g)TiCl4(g)+2Mg(s)→2MgCl2(l)+Ti(s) Suppose that an ilmenite-sand mixture contains 22.6 % ilmenite by mass and that the first reaction is carried out with a 91.1 % yield. If the second reaction is carried out with an 86.1 % yield, what mass of titanium can be obtained from 1.30 kg of the ilmenite-sand mixture?
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a) Copper solutions are typically blue to blue green in color. What color of light would they be expected to absorb in the greatest amount?
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Red |
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Violet |
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Blue |
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Green |
b) Based on your answer to the previous question (hopefully you have the correct answer), what wavelength range would you expect to see the maximum absorption of light (in the visible range)?
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500 nm to 600 nm |
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400 nm to 500 nm |
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300 nm to 400 nm |
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600 nm to 700 nm |
c) Given the information that the tartrate ion is the conjugate base of a weak acid, how do you expect the solubility of copper (II) tartrate to be affected by pH?
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decreased with lower pH. |
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increased with lower pH. |
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most soluble at pH = 7 |
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no change in solubility with pH. |
d) It was an intention to have a common ion experiment with the lab, but it did not work when we tested the experiment. What would the solubility of copper (II) tartrate be in a solution that contains 0.19 M sodium tartrate? (Use the literature for copper (II) tartrate Ksp = 4.0 x 10-4) Please enter answer in standard notation.
e) Your value for Ksp will not be the same as the literature. It may not even be close. It is likely to be larger than the literature value. What is one logical reason your value may be larger?
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evaporation of water leads to a more concentrated solution with greater solubility. |
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the accuracy of our spectrometers leads to lower than expected copper concentration readings. |
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the gravity filtration used might not be very effective at removing small undissolved solid particles from the saturated solution. |
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students just cannot get results that are as good as trained experts. |
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Calculate the mass of NaCN that must be added to 250.0 mL of water in order to obtain a solution having a pH of 11.25? [Ka of HCN = 4.9 × 10–10] Also, calculate the % ionization of the of the solution.
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Theory of enzymes. [Indicate whether the following statements are true or false by writing T or F in the spaces provided.] _____ Enzymes catalyze reactions by increasing the reaction free energy (ΔG). _____ Enzyme are remarkable for their substrate specificity. _____ Enzyme can convert light energy into chemical or mechanical energy. _____ Catalytic residues in enzymes can include amino acid side chains, RNA bases, and other organic cofactors. _____ Michaelis-Menten kinetic theory only applies to enzymes with single substrates. _____ Enzymes bind transition-state analogs more tightly than substrates. _____ At high substrate concentration, reactions are rate-limited by how rapidly enzymes convert substrates into products. _____ KM = KD when kcat >> k-1 _____ kcat / KM is equivalent to a second-order rate constant. _____ Enzymes can use electrostatics to exceed the rate of diffusion (bimolecular collision of substrate with enzyme’s active site). _____ Drugs that bind to an allosteric site on an enzyme cause a decrease in kcat
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Consider the reaction Mg(s)+Fe2+(aq)→Mg2+(aq)+Fe(s) at 73 ∘C , where [Fe2+]= 3.70 M and [Mg2+]= 0.310 M .
What is the value for the reaction quotient, Q, for the cell?
What is the value for the temperature, T, in kelvins?
What is the value for n?
Calculate the standard cell potential for
Mg(s)+Fe2+(aq)→Mg2+(aq)+Fe(s)
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