Calculate the pH at the equivalence point in titrating 0.034 M solutions of each of the following with 0.093 M NaOH. (a) periodic acid (HIO4) pH = (b) hydrocyanic acid (HCN), Ka = 4.9e-10 pH = (c) arsenous acid (H3AsO3), Ka = 5.1e-10
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5. A sample of N2 gas at 298 K and 1 atm. The diameter of N2 molecule is d = 3.6 × 10-10 m. (1) Calculate the collisions per second that one molecule of N2 make. (II) Calculate the mean free path 2 in meter. 6. An ideal gas has absorbed 900 J as a heat energy and the volume of the gas was decreased from 20 L to 10 L at constant external pressure of 5 atm. (1) The work done on the system (in J) in this process is: (II) The internal energy change (AU) of the system (in J) in this process is: 7. A cylinder with a piston contained 5 mole of helium (He). The system allowed to expand at constant pressure after adsorbing 25 kJ energy as a heat. (Knowing that Cy =12.47 J/mol.K) (1) Calculate AH (in J) for the process? (II) Calculate AU (in kJ) for the process?
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Electrochemistry is the study of the conversion between chemical and electrical energy. Describe how oxidation-reduction reactions are used to make a battery, converting the chemical energy from the reactions to electrical energy.
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1. Farmers who raise cotton onve used arsenic acid, H3AsO4, as a defoliant at harvest time. Arsenic acid is a polyprotic acid with K1 = 2.5 * 10-14, K2 = 5.6 * 10 -8 , and K3 = 3 * 10 -13 .
What is the pH of a 0.500 M sol'n of arsenic acid?
answer ) 1.96
3. A solution is prepared by adding 0.10 mol of KCH3COO, to 1.00 L of water.
Which statement about the sol'n is correct?
a) the sol'n is basic.
b)the sol'n is neutral
c) the sol'n is acidic
d) the concentrations of K+ ions and CH3COO- ions will be identical
e) the concetnration of CH3COO- ions will be greater than the concetnraion of K+ ions.
4. A sol'n is prepared by adding 0.10 mol of KCL, to 1.00 L of water. Which statement about the sol'n is correct?
a) the sol'n is basic
b) the sol'n is neutral
c) the sol'n is acidic
d)one need to know the temperature before any of the above predictions can be made.
e) the values for Ka and Kb for the species in sol'n must be known before a prediction can be made.
I already knew the answers except #2, but I don't know the reason why.
Please explain the questions to me. Thanks!
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Consider the hypothetical heteronuclear diatomic molecule XY where Y is more electronegative than X. Using only the p orbitals from each atom, construct a molecular orbital diagram. For each unique type of bond and anti-bond, sketch a picture of the molecular orbital resulting from the mixing of the atomic orbitals. Redundant molecular orbitals (i.e. those that only differ in orientation) need not be drawn. What is the bond order when there are 6 total electrons (X+Y p electrons)? Is that molecule paramagnetic or diamagnetic? What happens to the bond order if you add 1 more electron (7 total electrons)? Is that molecule paramagnetic or diamagnetic?
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Aspirin can be prepared from salicylic acid ( C 7 H 6 O 3 ), which has a molar mass of 138.12 g/mol, and acetic anhydride ( C 4 H 6 O 3 C 4 H 6 O 3 ), which has a molar mass of 102.04 g/mol. The density of acetic anhydride is 1.082 g/mL.
C 7 H 6 O 3 + C 4 H 6 O 3 ⟶ C 9 H 8 O 4 + C 2 H 3 O 2
What is the theoretical yield of aspirin ( C 9 H 8 O 4 ), which has a molar mass of 180.15 g/mol, possible when reacting 3.19 g of salicylic acid with 3.75 mL of acetic anhydride?
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The activation energy of an uncatalyzed reaction is 70.0 kJ/mol. When a catalyst is added, the activation energy (at 20.0 C) is 42.0 kJ/mol. Theoretically, to what temperature (C) would one have to heat the solution so that the rate of the uncatalyzed reaction is equal to the rate of the catalyzed reaction at 20. 0 C? Assume the frequency factor A is constant, and assume the initial concetrations are the same.
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a. Give one safety hazard when using the Bunsen burner
and one precautionary to avoid this hazard.
b. What safety measures do you need to practice when using the oven
to dry the solid product?
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To prevent brain damage, a standard procedure is to lower the body temperature of someone who has been resuscitated after suffering cardiac arrest. What is the physiochemical basis for this procedure?
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The pH of an aqueous solution of 0.572 M caffeine (a weak base with the formula C8H10N4O2) is:
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Two thousand (2,000) pigs in the growing-finishing stage (60 kg) are housed at a temperature (Ti) of 15 C. The indoor relative humidity (RHi) should not exceed 70%. The outdoor air conditions are To = -10 C and RHo = 50%. The UA value for the structure is 10,050 J/s.C. Will supplemental heat (Qsupp) be required for this structure, if so how much (J/s)?
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At what point(s) during the oscillation of a spring that obey's Hooke's law is the force on the mass the greatest?
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What is the difference between a reversible and irreversible process in chemistry?
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Given these reactions,
X(s) + 1/2 O2(g) -----> XO(s) Delta H = -699.3 kJ/mol
XCO3(s) -------> XO(s) + CO2(g) Delta H = +328.3 kJ/mol
what is Delta Hrxn for this reaction?
X(s) + 1/2 O2(g) + CO2(g) -------> XCO3(s) Delta H = kJ/mol
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Calculate the equilibrium constant for the reaction between Ni2+(aq) and Zn(s) under standard conditions at 25∘C.
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