Suppose that the microwave radiation has a wavelength of 12.4 cm. How many photons are required to heat 305 mL of coffee from 25.0 ∘C to 62.0 ∘C? Assume that the coffee has the same density, 0.997 g/mL , and specific heat capacity, 4.184 J/(g⋅K) , as water over this temperature range.

A generic salt, AB2, has a molar mass of 189 g/mol and a solubility of 3.80 g/L at 25 °C. What is the Ksp of this salt at 25 °C?

In each othe following compounds, which compound is likely to be more soluable in water?

Please explain your answers.

A). CCl4 or CHCl3

B). CH3OH or C6H11OH

C). NaF or MgO

D). CaF2 or BaF2

which of the following correctly represents the second ionization of copper?

a) Cu ⁺ (g) + e- ---> Cu²⁺ (g)-

b)Cu (g) ---> Cu ⁺ (g) + e-

c) Cu⁺ (g) ---> Cu²⁺ (g) + e-

d) Cu ^- (g) + e- ---> Cu^2- (g)

e) Cu⁺ (g) + e- ---> Cu (g)

I have the answers i just don't understand hoe to do it. please explain step by step. thank you!

A weak acid (HA) has a pKa of 4.666. If a solution of this acid has a pH of 4.294, what percentage of the acid is not ionized? (Assume all H in solution came from the ionization of HA.)

Please help me out...I am seriously not sure where to begin. I converted pka to Ka but then I'm not sure where to go from there or if I am on the right track. Any detailed help of how to solve the problem would be appreciated. I don't want just the answer. Thank you!

Part A

Use standard enthalpies of formation to calculate ?H?rxn for the following reaction.
C2H5OH(l)+3O2(g)?2CO2(g)+3H2O(g)

Express your answer using four significant figures.

Part B

Use standard enthalpies of formation to calculate ?H?rxn for the following reaction.
CH4(g)+2O2(g)?CO2(g)+2H2O(g)

Express your answer using three significant figures.

Part C

Use standard enthalpies of formation to calculate ?H?rxn for the following reaction.
C(s)+O2(g)?CO2(g)

Express your answer using four significant figures.

Part D

Use standard enthalpies of formation to calculate ?H?rxn for the following reaction.
CaO(s)+CO2(g)?CaCO3(s)

Express your answer using four significant figures.

You decide to construct a zinc/aluminum galvanic cell in which the electrodes are connected by a wire and the solutions are connected with a salt bridge. One electrode consists of an aluminum bar in a 1.0 M solution of aluminum nitrate. The other electrode consists of zinc bar in a 1.0 M solution of zinc nitrate. a. Which electrode is the cathode and which is the anode? b. What is the direction of electron flow? c. What chemical reactions are occurring at each electrode? d. What is the overall balanced chemical reaction? e. After a period of time, will the bar of zinc become heavier, lighter or stay the same? What about the aluminum bar? f. What is the standard cell potential?

Calcuate the pH when 80 mL of 1.25 M HCL is added to 779 mL of 1.60 M of sodium acetate.

Please show two different ways hows to solve with steps and forumulas. Thanks!

Properties of Enzymes

1. The concentration of an enzyme within a cell is extremely low relative to other material present, yet functions effectively in its metabolic role. How can an enzyme function and never seem to run out?

2.Name 4 factors which affect the activity of an enzyme.

3. A chemist found that a reaction did not take place under any set of conditions. If the chemist added a catalyst, would the reaction then occur? Explain your answer.

4.The rate of an enzyme-catalyzed reaction usually increases with temperature, but then decreases after reaching the “optimal temperature”. Why does this take place?

5.Why does saliva hydrolyze starch in the mouth but not in the stomach?

6.For a given enzyme-catalyzed reaction, on a molar basis, substrate concentration increases from two to four times the enzyme concentration (double). Would the rate of the reaction also double? Explain your answer.

a. What is the pH of a 0.25 M lactic acid (CH3(CH2)COOH) solution? Known: pKa = 3.85
I set the equation up as CH3(CH2)COOH –> CH3(CH2)COO- + H3O+. My final answer I got was pH = 3.99.

b. Assume you had enough solid sodium lactate (NaCH3CH(OH)COO) to cause the lactate ion (CH3CH(OH)COO-) concentration in the solution to increase to 0.20 M. what is the pH of the solution after the addition of sodium lactate to lactic acid?
I have no idea what to do with this one, but I’m assuming Na is a spectator ion?

Please show the work necessary for part b, and part a if my answer is incorrect. Thanks.

Isopropyl alcohol is composed of C , H and O combustion of 0.255g of isopropyl alcohol produces 0.561g of co2 and 0.306g of h2o . Determine empirical formula of isopropyl alcohol Cx Hy Oz ? ?

Please I need the answer with explantion ^_^

Calculate the pH for each of the following cases in the titration of 25.0 mL of 0.140 M pyridine, C5H5N(aq) with 0.140 M HBr(aq): (a) before addition of any HBr (b) after addition of 12.5 mL of HBr (c) after addition of 23.0 mL of HBr (d) after addition of 25.0 mL of HBr (e) after addition of 31.0 mL of HBr

For the diprotic weak acid H2A, Ka1 = 4.0

The pH of buffer solutions.

Weight of NaC2H3O2*3H2O =3.47g

pH of original buffer soution = 4.53

pH of buffer + HCl = 3.94

pH of buffer + NaOH = 5.00

Additional details: approximately 8.8 mL of 3M acetic acitd was added to the 3.47g of NaC2H3O2*3H2O. And approximately 56.0mL of distilled water. (This makes the buffer solution) This solution was then split in half. To one half 1 mL of 3M HCl was added. To the second half 1mL of 3M Na OH was added.

Calculate the pH of buffer.

Calculate the pH of buffer + HCl

Calculate the pH of buffer + NaOH

Please show all calculations and work.

please help me. I confused

A fictional company has been producing propene oxide, C3H6O, from propene, C3H6, with a 96.0% yield. The process requires the use of a compound called m-chloroperoxybenzoic acid, C7H5O3Cl, which can be abbreviated as mCPBA. The entire reaction takes place in the solvent dichloromethane, CH2Cl2:

C3H6+C7H5O3ClCH2Cl2−−−⟶96.0% yieldC3H6O+C7H5O2Cl

The initial propene concentration in the solvent is 21.0 g/L.

Consider the prices of the following substances.

Also consider that the cost of waste disposal is $5.00 per kilogram of propene oxide produced.

A relatively simple way of estimating profit is to consider the the difference between the cost (the total spent on materials and waste disposal) and the earnings (the price at which the product can be sold).

Calculate the profit from producing 26.00 kg of propene oxide.