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Physical Chemistry

pH of Solution During Titration Process

Q1: What is the pH of a 0.35 M solution of a weak acid HA with Ka = 1.41×10^-8? Q2: A 25.0 mL sample of the acid is titrated against 1.9 M NaOH. What is the pH after 5.0 mL of the base has been added? Q3: What is the pH after 10.0 mL of base has been added? Q4: What is the pH when 30.0 mL of base have been added?


Glauber's salt, sodium sulfate decahydrate (Na2SO4 * 10H2O) undergoes a phase transition (that is melting or freezing) at a convenient temp of 32 degrees C Na2SO4 * 1o H2O(s) yields Na2SO4 * 10 H2O(l) Change H = 74.4 kJ/mol As a result this compound is used to regulate the temperature in homes. It is placed in pl

Calculate the work done (in Joules) when 33.3g of tin dissol

Calculate the work done (in Joules) when 33.3g of tin dissolves in excess acid at 1.04 atm and 22 degrees C. Assume ideal gas behavior. Sn(s) + 2H(aq) yields Sn2+(aq) + h2(g) I realize the equations PV=nRT and w=-p (change V) but have converted and can't seem to get it right?

Energy in chemical reactions

See the attached document and find the heat of reaction for each set of reactions. Reaction 1: Heat of Dissolution of NaOH Reaction 2: Heat of Reaction Between Aqueous NaOH and Aqueous HCl Reaction 3: Heat of Reaction Between Solid NaOH and Aqueous HCl Questions: 1. Write the net ionic equation for each reaction,

Molecules and Ideal Gas Law

1. A cylinder contains a mixture of hydrogen and chlorine molecules. Compare without doing any calculations: a) the relative mass of the molecules b) the temperature of each gas c) the average kinetic energy of the molecules d) the average speed of the molecules. 2. Find the number of atoms in a) 52.5g of calcium metal

Buffer HEPES and MES got mixed. Identify which beaker contains HEPES.

You and a lab parnter prepare buffers to use in an experiment. Your partner prepares 200 ml 50 mM MES pH 6.0 while you prepare 200 ml of 50 mM HEPES pH 6.0. (MES and HEPES are the abbreviated names for two biological buffers often used in research labs). HEPES has MW 238.3 and pK = 7.48 MES has MW 195 and pK = 6.1 1. How

pH Determination After Titration

6. What is the hydrogen ion concentration of a solution with a pH = 4.54? a. 2.9 x 10^-19 b. 1.1 x 10^-2 c. 7.8 x 10^-5 d. 2.9 x 10^-5 e. 3.5 x 10^-10 16. What is the pH of a solution after titrating 25.0 mL of 0.500M HCOOH with 15.0 M of 0.500 M NaOH? a. 8.78 b. 3.57 c. 3.91 d. 10.43 e. 5.22 17. What is the pH

Percent by mass calculation

6. Assume that coal can be represented by the formula C135H96O9NS What is the percent of nitrogen by mass in this coal? If three tons of coal were burned completely, what mass of nitrogen in NO would be produced. Please show calculations. 7. This unbalanced equation represents the las step in the production of pure sil

Chemistry Questions

1. Which of these has the lowest concentration of hydrogen ions: 0.1 M HCL 0.1 M NaOH 0.1 M H2S04 pure water. Explain your answer 2. One reagent bottle on the shelf in a laboratory is labelled 12 M H2SO4 and another is labelled 12 M HCL A. How does the number of moles of H2S04 in 100 ml of 12 MH2SO4 solution comp

Standard free energy change for reactions

1. The Standard free energy change for the following reaction is -33.2 kJ/mol and the equilibrium constant Kp=6.59x105 at 25 C. N2(g) + 3H2 (g) <- -> 2NH3 (g) In a certain experiment, the initial pressures are P(H2)=0.25 atm, P(N2)= 0.87 atm and P(NH3)=12.9 atm. Calculate Delta G for the reaction at these pressures and pre

molarity of solution

1. Calculate the molarity of the following solutions from this acid-base titration data: a. If 250 ml of Ba(OH)2 of unknown concentration with a methyl red indicator present is titrated with [0.325 M] HNO3, the yellow solution turns red after 36.4 ml of the HNO3 is added. What is the molarity of the Ba(OH)2 solution? b.

Chemistry Help

1. How many grams of CO2 would be formed from 20 grams of C8H10 in the following (UNBALANCED) reaction? C8H10 + O2 --> CO2 + H2O 2. How many moles of CO2 would be formed from 40 grams of CaCO3 in the following (UNBALANCED) equation? CaCO3 + HCl --> CaCl2 + CO2 + H2O 3. A gas sample has an original volume of 700 ml when

Calculate the molar mass of geraniol

See attached file for full problem description. 1. The volatile organic compound geraniol, a component of oil of roses, is used in perfumery. It was found that the density of the vapor at 260ºC is 0.480 g/L when the pressure is 103 Torr. Calculate the molar mass of geraniol. 2. consider the following apparatus. Calculat

Titration of a Strong Acid

Procedure 1 (click to view assignments for this procedure) PLEASE NOTE: Titration requires several steps in order to obtain exact results. 1. Take a clean Erlenmeyer flask from the Glassware shelf and place it on the workbench. 2. Add 25 mL HCl (of unknown concentration) to the flask. 3. Add 2 drops of phenolphthal

acid base titration.

See attached file for full problem description. 13. A hydrocholoric acid solution is standardinzed by titrating 0.4541 g of primary stardard tris(hydroxymethyl)aminomethane. If 35.37 mL is required for the titration, what is the molarity of the acid? 15. A sodium hydroxide solution is standardized by titrating 0.8592 g of

Balanced & Net Ionic Equations

Write the balanced molecular equation, complete ionic and net ionic equation for the following acid base reaction. HCL(aq) + NH3(aq) NH3 is an exception, so I'm not sure what to do with it.

Salts and Their Reactions

7. When 1.00 grams of chromium metal is heated in excess iodine, 8.301 rams of chromium iodide salt is formed. Calculate the empirical formula of this salt. 8. When a calcium carbonate tablet is ingested, it dissolves by the reaction of stomach acid, which contains hydrochloric acid. The unbalanced equation for this reaction

PH, pOH, PKw

Calculating pH, POH, PKa, PKb. 37) PH 0.600 M solution of Na2S Sodium sulfide is a salt of a weak acid (hydrogen sulfide) and a strong alkali (sodium hydroxide). It therefore undergoes hydrolysis in water. Na2S = 2Na+ + S2- S2- + 2H2O = H2S + 2OH- Kh = [H2S][OH-] [S2-] [OH-] = Kh[S2-] [H2S] PO

Chemical breakdown of toothpaste

A toothpaste contains 0.24% by mass of sodium fluoride used to prevent caries (cavities) and 0.30% by mass of triclosan (C12H7Cl3O2). A PRESERVATIVE + ANTIGINVITIS AGENT. a) How many moles of NaF are in a tube of toothpaste b) How many moles of F- are in a tube? c) How many grams of Na+ are in 1.50g of toothpaste? d) How man

Purity of Zn(OH)2

The purity of a 0.287 -g samole of Zn(OH)2 is determined by titrating with a standard solution, requiring 37.8 mL. The HCL solution was standardized by precipitating AgCl in a 25.0-mL aliquot and weighing (0.462 g AgCl obtained). What is the purity of the Zn(OH)2 ?

What is the heat of combustion per gram of butane?

5. The combustion of butane produces heat according to the equation 2C4H10(g) + 13O2(g) &#61614; 8CO2(g) + 10H2O(l) &#61508;H° = -5,314 kJ What is the heat of combustion per gram of butane? A.-32.5 kJ/g B.-45.7 kJ/g C.-91.5 kJ/g D.-2,656 kJ/g E.-15,440 kJ/g 6. The freezing of water is an example of an exotherm

Calorimetry, calculations of heat energy required etc.

7. It takes 585 J of energy to raise the temperature of 125.6 g mercury from 20.0 degrees C to 53.5 degrees C. Calculate the molar heat capacity of mercury in J/(mol degrees C). 8. The specific heat capacity of silver is 0.24 J/(g x degrees C). It takes 3.57 kJ of energy to heat a sample of pure silver from 12.0 degrees C

Analytical Chemistry Questions: Ionic Strength

1. A and B react as follows: A + B = C + D. The equilibrium constant is 2.0 x 10^3. If 0.30 mol of A and 0.80 mol of B are mixed in 1 L, what are the concentrations fo A, B, C, and D after reaction? 4. The dissociation constant for hydrocyanic acid, HCN, is 7.2 x 10^-10. Calculate the percent dissociation of a 1.0 x 10^-3 M s