Organic Chemistry : HNMR QUESTIONS

What is the relationship between the # of scans and the # of signals?

What are limitations to HNMR?

What are "lock signals" in HNMR?

A sample of rainwater is observed to have a pH of 7.4. If only atmospheric CO2 at 390 ppm and limestone dust are present in the atmosphere to alter the pH from a neutral value, and if each raindrop has a volume of 0.02 cm3, what mass of calcium (in ng) is present in each raindrop? (Do not make any simplifications.)

Note: the answer is 59 ng. some say 0.02 cm3 rain drop is equal to 0.0134 L, how did that calculation occur?

Explain motions in catalysis

Aqueous sulfuric acid (H2SO4) reacts with solid sodium hydroxide (NaOH) to produce aqueous sodium sulfate (Na2SO4) and liquid water (H2O). If 3.37 g of water is produced from the reaction of 13.7 g of sulfuric acid and 20.6 g of sodium hydroxide, calculate the percent yield of water.

Predict whether each of the following solvents is miscible or immiscible with water.

ethanol C2H5OH
toluene C7H8
trichloroethylene C2HCl3
acetic acid CH3COOH

Please show work on how to determine miscibility. And determining how it is polar or non-polar.

Thank you

1. Some commercial drain cleaners contain a mixture of sodium hydroxide and aluminum powder. When the mixture is poured down a clogged drain, the following reaction occurs: 2NaOH(aq) + 2Al(s) + 6H2O(l) → 2NaAl(OH)4(aq) + 3H2(g) The heat generated in this reaction helps melt away obstructions such as grease, and the hydrogen gas released stirs up the solids clogging the drain. Calculate the volume of H2 formed at 25.5°C and 1.00 atm if 3.75 g of Al is treated with an excess of NaOH.

2. When ammonium nitrite (NH4NO2) is heated, it decomposes to liquid water and nitrogen gas. This property is used to inflate some tennis balls. (a) Write a balanced equation for the reaction. Include phase symbols. NH4NO2(s) → ___ (b) Calculate the quantity (in grams) of NH4NO2 needed to inflate a tennis ball to a volume of 74.59 mL at 1.63 atm and 22°C. Assume the volume of water produced is negligible.

What is the pH of a solution made by dissolving 2.81 grams of calcium fluoride in enough water to make 450 mL of solution? The Ka for HF is 6.8x10–4.

Write a chemical equation for the hydrolysis reaction that explains why an aqueous solution of CH3NH3Cl is acidic.

Calculate the pH of a 1.22×10-2 M solution of the decongestant ephedrine hydrochloride if the pKb of ephedrine (its conjugate base) is 3.86.

Part A

Watch the video on the explosive decomposition of nitrogen triiodide, NI3, and determine which of the following statements are correct.

Check all that apply.

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Enthalpy—an extensive property

Enthalpy is an extensive property, and its value depends upon the amount of reactants undergoing the reaction. The enthalpy of the reaction when 5 molof NI3 reacts will be five times higher than that when 1 mol of NI3 reacts.

For example, consider a decomposition reaction of NI3:

2NI3(s)→N2(g)+3I2(g), ΔHrxn=−290.0 kJ

When 2 mol of NI3 decomposes, the enthalpy of the reaction is −290.0 kJ.

If 5 mol of NI3 decomposes, the enthalpy of the reaction will be (52×−290.0) = −725.0 kJ.

Part B

The decomposition of NI3 to form N2 and I2 releases −290.0 kJ of energy. The reaction can be represented as

2NI3(s)→N2(g)+3I2(g), ΔHrxn=−290.0 kJ

Find the change in enthaply when 12.0 g of NI3 decomposes.

Express your answer to three significant figures and include the appropriate units.

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Calculation of the heat of reaction based on the standard heat of formation

The enthalpy change for the formation of 1 mol of a substance in its standard state from its constituent elements in their standard states is called the standard heat of formation. It is denoted as ΔH∘f.

If the standard heat of formation of the reactants and the products is known, the standard heat of reaction can be calculated using the formula

ΔH∘rxn=∑npΔH∘f(products)−∑nrΔH∘f(reactants).

Here, np is the total number of moles of products, and nr is the total number of moles of reactants.

Part C

Consider the exothermic reaction

CH4(g)+2O2(g)→CO2(g)+2H2O(g)

Calculate the standard heat of reaction, or ΔH∘rxn, for this reaction using the given data. Also consider that the standard enthalpy of the formation of elements in their pure form is considered to be zero.

Express your answer to four significant figures and include the appropriate units.

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A sample of 0.320 M hydroxylamine (HONH2) is reacted with 0.210 M HBr solution. How many mL of the HBr would be required to exactly neutralize 25.0 mL of the HONH2 solution? answer: 38.10mL. What would be the pH of the solution from part E?

In polymer Chemistry, Give description on a specific characterization method.

When calcium carbonate is added to hydrochloric acid, carbon dioxide, and water are produced.

CaCO3(s)+2HCl(aq)--->CaCl2(aq)+H2O(l)+CO2(g)

a. How many grams of calcium chloride will be produced when 27.0g of calcium carbonate are combined with 12.0g of hydrochloric acid?

2. Which reactant is excess and how many grams of this reactant will remain after the reaction is complete?

Suppose that the partition coefficient for an amine, B, is K = 3.0 and the acid dissociation constant for BH+ is Ka = 1.0 x 10−9. If 50.0 mL of 0.010 M aqueous amine is extracted with 100.0 mL of solvent two times, what percentage amine remains in aqueous solution if the pH of the aqueous phase is 9.00?

Complete the stoichiometry table using the starting values provided. reagent molecular weight mass (g) mmoles equivalents density (g/mL) vol. (mL) bromobenzene 0.355 1.993 magnesium 1.501 benzophenone 1 diethyl ether 27.063 theoretical product triphenylmethanol melting point of triphenylmethanol (°C) Please show calculations also especially for magnesium, benzophenone, diethyl ether, and triphenylmethanol

How many milligrams of magnesium metal must react with excess HCI to produce 50.50 mL of H2 (g), measured at 25 degrees Celsius and 775 torr? Show all calculations in this problem.

Mg (s) + 2 HCl (aq) --> MgCl2 (aq) + H2 (g)

1. Calulate the %(m/v) ad M of a solution made by dissolving .4g of K2SO4 in water and diluting to a volume of 50.00 ML.

2. Show (by use of eq. 5) how the first dilution of the 1 M solution of NaCl results in a .01 M Solution

3. How many mL of a stock solution of a 5.0% solution of NaNo3 are needed to make 1.5 L of a .25 % solution of NaNo3.

Please show work