Phosphine (PH₃) decomposes into phosphorus and molecular hydrogen:
4PH₃(g) → P₄(g) + 6H₂(g)
Experiments show that this is a first-order reaction, with a rate constant of 0.0173 s^-1 at 650°C. Identify each of the following statements about this reaction as true or false. (Use the drop-down menu and select "True" or "False" for each. You must get all 4 correct.)
True/False  The mechanism for this reaction must involve two or more elementary steps.
True/False  The activation energy for the reaction cannot be determined without additional data.
True/False  The rate constant would be smaller than 0.0173 s^-1 at 500°C.
True/False  The rate-determining step for the reaction could involve a bimolecular collision between two PH₃ molecules.

Chemical Engineering Problem:

A vapor composed of 0.25 mole fraction ethanol and 0.75 mole fraction acetic acid at 120.0 mmHg (absolute), is in equilibrium with a liquid phase also composed of ethanol and acetic acid. Assume that the liquid is an ideal solution and apply Raoult\'s law to find the following. What is the temperature of the liquid?

What is the Temperature of the fluid? _____C

What are the mole fractions of the liquid phase?

X_E=_____mol ethanol/mol

X_A=_____mol acetic acid/mol

4 liter sealed container contains water vapour at 0.4 atm and 90°C. a) What is the dew point of the vapour? b) Determine the percentage of the vapour that will condense if the system is cooled to 50°C.

Part A

Determine the [H3O+] of a 0.250M solution of formic acid.

Express your answer using two significant figures.

[H3O+] = ???

Part B

Determine pH of this solution of formic acid.

Express your answer to two decimal places.

pH=???

500.0 mL of 0.140 M NaOH is added to 595 mL of 0.200 M weak acid (Ka = 2.29 × 10-5). What is the pH of the resulting buffer? HA (aq) + OH (aq) ---> H2O (L) + A (aq)

What compound is used as a standard for location of NMR signals?

Select one:

a. acetone, CH₃COCH₃

b. silicon grease

c. water

d. deuterated water, D₂O

e. deuterated chloroform, CDCl₃

f. trimethylsilane, (CH₃)₄Si

g. chloroform, CHCl₃

Menthol is a crystalline substance with a peppermint taste and odor. When 1.22 g of menthol is dissolved in 25.0 g of cyclohexane, the freezing point of the solution is lowered by 6.52 °C. The freezing point and Kf constant for cyclohexane can be found here. Calculate the molar mass of menthol.

A 9.65-L container holds a mixture of two gases at 31 °C. The partial pressures of gas A and gas B, respectively, are 0.171 atm and 0.877 atm. If 0.200 mol of a third gas is added with no change in volume or temperature, what will the total pressure become?

The flask shown here contains 1.04 g of acid and a few drops of phenolphthalein indicator dissolved in water. The buret contains 0.280 M NaOH. When titrated the end point of the solution is 26 mL.

What volume of base is needed to reach the end point of the titration?

Assuming the acid is monoprotic, what is its molar mass?

outline a lab experiment which could be done in order to determine delta H, delta G and dellta S of dissolution of Urea

Einstein predicted that the mean squared displacement of small particles due to diffusion (random motion, executed in small, discrete steps) would increase linearly with time. Prove it in a simple way.

1) Write a chemical equation describing the condensation process for N₂ and a chemical equation describing the freezing process for N₂. For each process discuss the change in enthalpy and entropy that occurs. For each process describe the conditions (in terms of temperature) that support a thermodynamically favorable change, and the conditions that do not support a thermodynamically favorable change.

For 550.0 mL of a buffer solution that is 0.185 M in CH3CH2NH2 and 0.175 M in CH3CH2NH3Cl, calculate the initial pH and the final pH after adding 0.020 mol of HCl. Express your answers using two decimal places separated by a comma.

In paper chromtography, what is the nature of the attractions between the stationary phase (cellulose) and the moving phase (hydrochloric acid/water/acetone) and the species ( Zn2+, Co2+, Cu2+, Cd2+ , Fe3+, and Ni2+ in two unknown solutions)  being separated, in particular what affects the Rf values and how?

Note: Filter paper (Whatman #1) serves as the stationary phase, and the mobile phase consists of a mixture of acetone and 6 M hydrochloric acid. A single spot of the mixture to be analyzed is applied near one edge of a sheet of filter paper. A spot of solution containing each of the cations that might be in the unknown mixture is also placed near the edge of the same sheet for comparison. The treated strip is then placed in a covered jar or beaker (which acts as a developing chamber) containing a shallow layer of the solvent mixture (see Figure 3). Since filter paper is very permeable to the solvent, the solvent begins to rise up the strip by capillary action. The various spots on the developed chromatogram will be highlighted by treatment with several chemical reagents to enhance their color. The reagents to be used are ammonia, dimethylglyoxime (DMG), and 8–hydroxyquinoline (oxine).

What is the pH of a solution made by mixing the following?

20.0 mL of 0.10 M HClO (K_a = 3.0x10^-8)

20.0 mL of 0.10 M KOH