Share
Explore BrainMass

Physical Chemistry

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

Empirical Formula & Products

A compound of bromine and fluorine is used to make UF6, which is an important chemical in processing and reprocessing of nuclear fuel. The compound contains 58.37% by mass of bromine. Determine its empirical formula. A) BrF B) BrF2 C) Br2F3 D) Br3F E) BrF3 Magnesium reacts with iron(III) chloride to from magnesium chlo

Gas Law State Assumptions

1.a) state the assumption associated with the model used to develop the Ideal Gas Law b) hence or otherwise describe under which physical conditions does the ideal gas law applies 2. Explain why hydrogen which has one electron in its lowest state, should in principle be a metallic conductor in its solid state whereas heli

Chemical: Gas-Related Problems

6. A gas operates under isothermal conditions. The initial volume of gas in the pump is 22.4 liters, the pressure is one atmosphere and temperature is 273 deg K. if 0.6 mole of gas is released and the volume remains unchanged calculate the new pressure. 7. Calculate the minimum energy a photon must have to produce an electr

Volume of the Gas in the Cheetos

The gas in a sealed bag of Cheetos? has a volume of 500 mL in Pueblo where the atmospheric pressure is 600 mm of Hg. You take this bag to the top of Pikes Peak where the pressure is 420 mm of Hg. Assuming the temperature on the Peak is the same as Pueblo (hot day on the Peak!), what is the volume of the gas in the Cheetos? bag o

Buffer solution problem and problem using Henderson-Hasselbalch (H-H) equation

13. What is the pH of a solution prepared by mixing 50.00mL of 0.10 M NH3 with 25.00mL of 0.10 M NH4Cl? Assume that the volume of the solutions are additive and that Kb= 1.8 x 10 -5 for NH3. 14. What is the pH of a solution made by mixing 30.00mL of 0.10M acetic acid with 30.00mL of 0.10 M KOH? Assume that the volumes of the

Hydrogen phosphate buffer system

Please help with the following problem. Buffer solutions have the unique ability to resist changes in PH when an acid or base is added to them. One important buffer system that helps to maintain blood pH at a constant value of 7.4 is the hydrogen phosphate buffer. The chemical equation for this for this buffer system is: H2P

What Favors the Reverse Reaction?

Consider the equilibrium represented by the following equation: Heat + H2O(l)<>H2O(g) in which T=373K, P=101kPa Which of the following will favour the reverse reaction? (a) The total volume of the system is increased. (b) Boiling water is added to the system. (c) Water vapour is removed from the system. (d) The sy

Truth about Systems at Equilibrium

Consider a stoppered flask containing benzene, iodine, and air, which has reached equilibrium at 298K. Which one of the following statements concerning the system at equilibrium is true? (a) The pressure of the vapour phase is not constant. (b) Evaporation of the liquid continues. (c) The colour of the liquid phase will

Reaction Mechanisms of Tin

For these reactions I need mechanisms like "with curly arrows" like I-I bonds breaking and what happens next: 1. Sn + 2I2 -> SnI4 (Ac2O,AcOH, reflux) 2. SnI4 + 2PPh3 -> (PPh3)2SnI4 (CHCl3) 3. SnI4 + (Me2SO)2 -> SnI4(Me2SO)2 (CH2Cl2)

Diffussion controlled electrolysis

Diffussion controlled electrolysis proceeds on (a) planar and (b) spherical electrode under the conditions: n = 1, C = 1 mM, A= 0.04 cm^2, D = 1.5x10^-5 cm^2/s. Calculate the current (i) in both cases at t = 0.5, 1, 3, 10 sec. How long can the electrolysis proceeed before the current at the spherical electrode exceeds that