Chemistry Charles's Law Post-Laboratory Questions

1. Serveral students performed this experiment without paying adequate attention to the details of the procedure. Briefly explain what effect each of the following procedural changes would have ont the size of the volume-to-temperature ratio calculated by the students.

A) One student failed to replenish the boiling water in the boiling-water bath as the flask was being heated. At the end of the 6 min of heating, the boiling water in the bath was only in contact with the lower portion of the flask.

B) Following the proper heating of the flask in the boiling water, a student removed the flask from the boiling-water bath but only partially immersed the flask in the ice-water bath during the cooling period.

C) A student neglected to close the pinch clamp before removing the flask from the boiling-water bath and immersing it in the ice-water bath.

D) One student neglected to measure the volume of the flask before leaving the laboratory. Because the procedure called for a 125-mL Erlenmeyer flask, the student used 125 mL as the volume of the flask.

Calculate the pH of a solution made by mixing 100.0 mL of 0.044 M NH_3 with 100.0 mL of 0.126 M HCl. (Kb for NH_3 = 1.8 x 10^-5)

Explain what Vmax and Km describe

1.Write the equilibrium expression for the dissociation of KHT (s) in water. B. Develop an ICE chart for the dissociation of KHT in water.

1. Show calculations and briefly describe how you will make the following solutions:

   1. 50.00 mL of 0.200 M Fe(NO3)3(aq) solution from iron(III) nitrate nonahydrate

   2. 200.00 mL of a 2.00 mM KSCN(aq) solution from potassium thiocyanate.

   3. 100.00 mL of 1.00 M CoCl2(aq) solution from cobalt(II) chloride hexahydrate.

2. Write the equilibrium expression for parts A, B, and C of the lab based on the equations that are shown in the prior section.

3. Look at the expression for cobalt complexation with chloride ions (Part B of the lab). How would doubling the amount of water in the reaction vessel affect the product concentrations compared to the reactant concentrations?

4. How is the [ ] used in metal complexes like the cobalt tetrachloride complex [CoCl4]2- different from the [ ] used in the general equilibrium expression that follows?

K=[B]2[C]/[A

Explain why using deionized water to rinse the walls of the flask have no effect on the reported results of titrations performed.

Which is (are) the spectator ion(s) in the following precipitation reaction (equation not balanced)? (NH4)3PO4(aq) + Al2(SO4)3(aq) --> AlPO4(s) + (NH4)2SO4(aq)

For a particular process q = 20 kJ and w = 15 kJ. Which of the following statements is true?

A. The system does work on the surroundings.

B. Heat flows from the system to the surroundings.

C. ΔE = 35 kJ

D. All of the these are true.

E. None of these choices are true.

Calculate the concentration of free mercury (II) ion, [Hg²⁺], in an aqueous solution that is initially 0.16 M Hg(NO₃)₂ and 3.2 M NaCl given that the K_f of HgCl₄^2- is 1.7*10¹⁶.

The answer is 2.2*10^-19 M, how?

What is the ratio [CH₃COOH]/[CH₃COO^-] in a solution made by mixing 100 mL of 0.500 M CH₃COONa with 50.0 mL of 0.0500 M NaOH? (CH₃COOH Ka = 1.8 x10^-5 )

• A.) 4.1 x 10^-5
• B) 2.2 x 10^-8
• C) 1.1 x 10^-8
• D) 3.3 x 10^-8
• E) 8.3 x 10^-9

At a certain temperature and total pressure of 1.2 atm, the partial pressures of an equilibrium mixture for 2A(g) <==> B(g) are Pa = 0.60 atm and Pb = 0.60 atm. After a disturbance, the system regains equilibrium with a total pressure of 1.9 atm. What is the partial pressure of A at the new equilibrium?

Answer in atm

Please show all work I have tried this problem twice and have gotten wrong answers would like to see the differences in steps.

Consider the titration of a 23.4 −mL sample of 0.125 M RbOH with 0.105 M HCl. Determine each quantity:

the pH after adding 4.1 mL of acid beyond the equivalence point

Express your answer using two decimal places.

A) Calculate E° for the reaction:

2 MnO₄^- + 10 Cl^- + 16 H₃O⁺ →2 Mn²⁺ + 5 Cl₂ + 24 H₂O

E°_{MnO4^-/Mn²⁺, H3O⁺} = +1.507, E°_Cl2/Cl^- = +1.358

Round your answer to 3 significant figures.

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B) Use standard reduction potentials to calculate ΔG° for the reaction:

3 I₂ + 5 Cr₂O₇^2- + 34 H₃O⁺ →6 IO₃^- + 10 Cr³⁺ + 51 H₂O

E°_{IO3^-/I2, H3O⁺} = +1.195, E°_{Cr2O7^2-/Cr³⁺, H3O⁺} = +1.232

1. A certain proton NMR spectrum (recorded on a 400 MHz NMR spectrometer) consists of one singlet and one doublet. The singlet has a chemical shift of 5.0 ppm. The doublet is 2600 Hz upfield from the singlet. Which one of the following statements is correct?

A) The chemical shift of the doublet (on the delta scale) is positive

B) The chemical shift of the doublet (on the delta scale) is negative

2. Which one of the following statements is correct?

A) The electromagnetic radiation used in IR spectroscopy is higher in energy than that used in X-ray crystallography

B) The electromagnetic radiation used in IR spectroscopy is lower in energy than that used in X-ray crystallography