A holding tank with capacity 5000 litres initially contains 1500 litres of 25 mM NaCl solution. a) What is the final concentration of NaCl (expressed in mM) if an additional 3000 litres of 25 mM NaCl solution is pumped into the tank? b) Instead of (a), if 3000 litres of water are added to the tank, what is the final concentration of NaCl (expressed in mM)? c) Instead of (a) or (b), if an additional 500 litres of 25 mM NaCl solution plus 3000 litres of water are added, what is the final concentration of NaCl:

iv. Expressed as ppm? (ppm means g per 106 g of solution) You can assume that the density of the solution (NaCl + water) is the same as the density of water – this assumption is appropriate since this is a dilute solution. Assume density of water to be 1 g/cm3 .

Note: mM means milli-molar (1 mM means 1 milli-mol/liter)

The generic reaction

2A?B

has the following rate laws:

forward reaction:reverse reaction:rate=kf[A]2rate=kr[B]

where kf is the rate constant for the forward reaction and kr is the rate constant for the reverse reaction. At equilibrium, the two rates are equal and so kf[A]2=kr[B]. The equilibrium constant for a reaction is related by the law of mass action to the rate constants for the forward and reverse reactions:

Kc=[B][A]2=kfkr

Formation of nitrosyl bromide

Nitrosyl bromide, NOBr, is formed in the reaction of nitric oxide, NO, with bromine, Br2:

2NO(g)+Br2(g)?2NOBr(g)

The reaction rapidly establishes equilibrium when the reactants are mixed.

A.

At a certain temperature the concentration of NO was 0.400 M and that of Br2 was 0.265M . At equilibrium the concentration of NOBr was found to be 0.250 M. What is the value of Kc at this temperature?

Express your answer numerically.

In organic chemistry lab we just completled a "Lidocaine Synthesis". I have some questions to clarify before we take the in class exam.

1. Based on apperence and melting point; how can we validate if the crystals are pure lidocaine?

2. When using the seperatory funnel in extraction, we washed the organic layer with water and would shake then drain the aqueous layer out. After a couple of washes with water, we then use HCL to extract and collect this aqueous layer seperatley. Following the extraction with HCL we then again washed the organic solution with water. Any of the washes with water were collected then combined at the end of using seperatory apparatus. Why would we wash the oganic layer with water again after using HCL? Does it yeild more product?

3. What compund were we dissolving in the aquoues extract?

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

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?

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.

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!

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?

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?

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.

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?

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?

The pH of an aqueous solution of 0.572 M caffeine (a weak base with the formula C₈H₁₀N₄O₂) is:

Two thousand (2,000) pigs in the growing-finishing stage (60 kg) are housed at a temperature (T_i) of 15 C. The indoor relative humidity (RH_i) should not exceed 70%. The outdoor air conditions are T_o = -10 C and RH_o = 50%. The UA value for the structure is 10,050 J/s.C. Will supplemental heat (Q_supp) be required for this structure, if so how much (J/s)?

At what point(s) during the oscillation of a spring that obey's Hooke's law is the force on the mass the greatest?