Extra Credit 15 Shawn Antoo
- Page ID
- 96897
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Q14.3.5
Household ammonia is a solution of the weak base NH3 in water. List, in order of descending concentration, all of the ionic and molecular species present in a 1-M aqueous solution of this base. Given the Kb of NH3 is 1.8E-5 for the current conditions.
Answer: [H2O] > [NH3] > [NH4+] = [OH-] > [H3O+]
Kb of NH3 is 1.8E-5, so there are more reactants than products meaning there is more NH3 than NH4+ and H3O+. Obviously H2O has the highest concentration.
Honors Level: List, in order of descending concentration, all of the ionic and molecular species present when 1ml of .15 M NaOH is mixed with 100ml of .2 M CH3CHOOH. Given the Ka of CH3CHOOH is 1.8E-5 for the current conditions.
.
Q15.1.X
Calculate the concentration of F– required to begin precipitation of CaF2 in a solution that is 0.010 M in Ca2+. Ksp is 3.5E-11 for the system.
Answer: Use ICEBOX. It's simple math.
3.5E-11= [2*F–]2 * [Ca2+]
3.5E-11= [2*F–]2 * [.01]
[F–]= 2.96E-5M required to precipitate solution.
Honors Level: Calculate the mass of CaF2 produced when 5g of Ca(NO3)2 is mixed with 3g of NaF in water, with a final volume of 500 mL. Ksp is 3.5E-11 for the system.
Q16.4.8
Among other things, an ideal fuel for the control thrusters of a space vehicle should decompose in a spontaneous exothermic reaction when exposed to the appropriate catalyst. Evaluate the following substances under standard state conditions as suitable candidates for fuels.
- Ammonia:
\(\ce{2NH3}(g)⟶\ce{N2}(g)+\ce{3H2}(g)\) - Ethane:
\(\ce{C2H6}(g)⟶\ce{2C}(g)+\ce{3H2}(g)\) - Hydrazine:
\(\ce{N2H4}(g)⟶\ce{N2}(g)+\ce{2H2}(g)\) - Hydrogen peroxide:
\(\ce{H2O2}(l)⟶\ce{H2O}(g)+\dfrac{1}{2}\ce{O2}(g)\)
Answer:
Use the Gibbs energy and Enthalpy of reaction tables to determine the delta g and h of reaction.
A. Delta G= (3)(0)+0+(2)(16.4)= 32.8KJ
Delta H= (3)(0)+0+2(45.9)= 91.8 KJ
Non-spontaneous endothermic reaction; not a good fuel
B. Delta G=(2)(671.3)+0+32= 1374.6KJ
Delta H= (2)(716.7)+0+84=1517.4
Non-spontaneous endothermic reaction; not a good fuel
C. Delta G= 0+0-159.4= -159.4 KJ
Delta H= 0+0-95.4= -95.4KJ
Spontaneous exothermic reaction; good fuel
D. Delta G= -288.6+120.4= -108.2KJ
Delta H= -241.8+136.3= -105.5KJ
Spontaneous exothermic reaction; good fuel
Honors Level: Since its very cold in space, calculate the gibbs energy at 25C (earth temperature) and -193C (space temperature) and state which is the best fuel.
Q5.4.20
Which produces more heat(energy, not heat; heat is a transfer of energy)?
\(\ce{Os}(s)⟶\ce{2O2}(g)⟶\ce{OsO4}(s)\)
or
\(\ce{Os}(s)⟶\ce{2O2}(g)⟶\ce{OsO4}(g)\)
for the phase change \(\ce{OsO4}(s)⟶\ce{OsO4}(g)\hspace{20px}ΔH=\mathrm{56.4\:kJ}\)
Answer: The reaction that leads to product in the solid phase releases more energy than the reaction that leads to product in the gas phase because a lot of energy is required to break almost all, if not all, the IMF's present in the solid phase, where as the solid phase retains those IMF's. Since the product in the solid phase did not use the energy to break IMF's, the energy would be released as energy in the surroundings, resulting in a larger change in enthalpy than the reaction that lead to products in the gas phase.
Honors Level: Why is water's heat of vaporization some much larger than its heat of fusion, in terms of IMF's?
Q10.4.3
Pressure cookers allow food to cook faster because the higher pressure inside the pressure cooker increases the boiling temperature of water. A particular pressure cooker has a safety valve that is set to vent steam if the pressure exceeds 3.4 atm. What is the approximate maximum temperature that can be reached inside this pressure cooker? Explain your reasoning.
Answer: Since no volume was given, make up a volume for the container and the amount of gas in the container. Assuming 1 liter and 5 moles of gas, the temperature would be 8.29K using the ideal gas equation, PV=nRT. (1)(3.4)=(50)(.083)T T=8.29K.
Honors Level: How much salt (NaCl) is required to have 1 liter of water boil at 100 C at .75 atm? Heat of vaporization is 40.65KJ/Mole and water has a vapor pressure of 24.8Hg at 25C.