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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Return to Assignment

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

Iron(III) oxide reacts with carbon monoxide according to the equation:

Fe2O3(s)+3CO(g)→2Fe(s)+3CO2(g)

A reaction mixture initially contains 22.10 g Fe2O3 and 14.00 g CO.

Once the reaction has occurred as completely as possible, what mass (in g) of the excess reactant remains?

Express your answer to three significant figures.

Suppose that in an alternate universe, the possible values of l were the integer values from 0 to n(instead of 0 to n−1). Assuming no other differences from this universe, how many orbitals would exist in each of the following levels?

n = 4

DQ 11: Given that the solubility product of PbI₂ is expressed as K_sp = [Pb²⁺][I^–]², calculate the K_sp of PbI₂ from the concentration of Pb²⁺ found in Step 6 of the Data Analysis. (Hint: Think about the stoichiometry involved when PbI₂ was initially formed… how much I^– was left unreacted?) Is PbI₂ a soluble or insoluble salt? Explain.

3mL of 0.05M KI was used and 1mL of 0.05 Pb(NO3)2 was used to make the PbI2 solution/yellow precipitate

All work must be shown below for credit.

(2 pts) Show a properly balanced chemical equation:

Pb(NO₃)_2(aq)+ 2KI_(aq)--> PbI_2(s)+2KNO^-_3(aq)

(4 pts) Determine the limiting reagent:

(2 pts) Calculate the K_sp of PbI₂:

(2 pts) Is PbI₂ a soluble or insoluble salt? Explain:

Consider a 0.20 M NH4Cl aqueous solution. Rank the following species in the solution from highest to lowest concentration.

NH3, Cl-, H2O, NH4+, OH-, H3O+

Consider a 0.10 M aqueous solution of sodium nitrite, NaNO2. Rank the following species in the solution from highest to lowest concentration.  

OH-, HNO2, NO2-, H3O+, H2O, Na+

The acetate ion is the conjugate base of acetic acid. The Ka of acetic acid is 1.76×10–5. What is the pH of a 0.100 M solution of sodium acetate?

Consider the titration of 60.0 mL of 0.100 M NH3 Kb= 1.8 x 10^-5 with 0.150 M HCl. Calculate the pH after the following volumes of titrant have been added: 40.5 mL & 60.0 mL

Two 2.0-cm-diameter insulating spheres have a 7.00 cm space between them. One sphere is charged to + 70.0 nC , the other to - 79.0 nC . Part A What is the electric field strength at the midpoint between the two spheres? Express your answer with the appropriate units.

Although coal is no longer the favored energy source, U.S. coal mines still produced close to a billion short tons of coal. Detail 5 different forms of coal, including activated carbon, and chemical products and health hazards related to each different form. Describe DOT recommended response actions to incidents involving a release of coal and/or carbon.