Calculate the pH of the solution that results from each of the following mixtures.

1. 160.0 mL of 0.27 M HF with 230.0 mL of 0.32 M NaF

2. 185.0 mL of 0.10 M C2H5NH2 with 275.0 mL of 0.22 M C2H5NH3Cl

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Ka of hydrofluoric acid is 6.8 x 10−4.

What volume of a 12.0 M KOH solution needs to be diluted to produce 475 mL of 3.10 M KOH solution?

Chemistry

1. In a Diels-Alder reaction, electron-withdrawing groups in the dienophile end up preferentially in

the _________ position, and the diene must be in the ____________ conformation.

A) Endo; s-cis C) Exo; s-trans

B) Endo; s-trans D) Exo; s-cis

2.What is the hybridization of the central carbon of allene (1,2-propadiene)? A) sp B) sp2 C) sp3 D) p

3.Which of the following corresponds to the COC bond angle in diethyl ether? A) 60o B) 110o C) 120o D) 180o

4.Which of the following terms best describes the reactive nature of an organolithium reagent?

A) Carbocation B) free radical C) electrophile D) nucleophile E) carbene

Calculate the concentration of all species (H₂SO₃),(HSO₃),(H₃O⁺),(SO₃^-2),(OH-), pH and pOH in a 1.41M Na₂SO₃ (sodium sulfite) solution. The ionization constant for sulfurous acid are

H₂SO₃+H₂O->HSO₃^-+H₃O⁺   Ka1=1.4x10^-2

HSO₃^-+H₂O->SO₃^-2+H₃O⁺ Ka2=6.3x10^-8

Answer the following questions (a through f) based upon a peptide sequence with the following amino acids (one-letter symbols are given): EHSGLR

(a) What are the full names and three-letter abbreviations of the amino acids?

(b) At physiological pH, what is the best description of the chemical properties of the side chains(R groups)? (Hint: Select between nonpolar, polar uncharged, positively charged, negatively charged)

(c) Draw the structure of this peptide at pH 7.0.

(d) What is the net charge of the molecule at pH 3, 8, and 11? (Use pKa values for side chains and terminal amino and carboxyl groups as given in Table 3–1.)

(e) Estimate the pI for this peptide.

(f) What type of intermolecular force could the side chains form with water? (Note that these are interactions are with water, not with other amino acids.)

Why ice is less dense as a solid than as a liquid?

why is this property so important for the fish and other wildlife that live in the lakes and ponds of indiana

Which of the following statements are correct?

a) HCFCs are used as the replacement of CFCs because they do not reach the Stratosphere.

b) HFCs are used as the replacement of CFCs (and HCFCs) because do not contain chlorine and so do not have the ozone depletion potential associated with the well-established chlorine catalytic cycles.

c) Climate projections indicate that the ozone layer will return to 1980 levels within the next 20 years.

In a chemical reaction, exactly 2 mol of substance A react to produce exactly 3 mol of substance B.

2A = 3B

How many molecules of substance B are produced when 28.2 g of substance A reacts? The molar mass of substance A is 17.9 g/mol.

Step 1. Convert the mass of A to moles.

__________________________________mol A

Step 2. Convert the number of moles of A to the number of moles of B.

___________________________________mol B

Step 3. Convert the number of moles of B to molecules of B.

___________________________________molecules of B.

1)Determine the pH of each solution.

Part A

0.20 M KCHO2

Express your answer to two decimal places.

Part B

0.21 M CH3NH3I

Express your answer to two decimal places.

Part C

0.22 M KI

Express your answer to two decimal places.

2)

Part A

Rank the following compounds in order of decreasing acid strength using periodic trends.

Rank the acids from strongest to weakest. To rank items as equivalent, overlap them.

LiH, H2O, HCl, HBr

Information regarding the question:

Concentration of NaOH=0.05138 M

Concentration of Crystal Violet Dye Solution=0.001 M

Room Temperature=25 degree Celcius

Absorbance from the device- spectrovis(spectrophotometer)

Time: Trial 1 Trial 2

0 0.089 0.430

30 0.106    0.323

60 0.121    0.248

90 0.106    0.187

120 0.063 0.141

150 0.045 0.109

180 0.028 0.082

210 0.023 0.060

240 0.014 0.045

270 0.010 0.036

300 0.005 0.027

330 0.003 0.017

360 0.000 0.015

390 -0.001 0.008

420 -0.002 0.006

450 -0.002 0.007

The following calculations must be handwritten in your notebook. – Conversion of %Transmittance to Absorbance ■ Only one handwritten sample is necessary ■ However, all of your %Transmittance values must be converted to Absorbance in your Data Table

–The steps you took to determine the order with respect to the Crystal Violet Dye (X in the example)

– The steps you took to determine the order with respect to the NaOH (Y in the example)

– The steps you took to determine k – The overall, Modified Rate Law ■ With your values for X, Y, and k inserted into the equation

– Solve the Rate Law ■ Insert in all values necessary Result

ammonia is a common constituent of many natural waters and wastewaters. when water containing ammonia is treated at a water treatment plant, the ammonia reacts with the disinfectant hypochlorous acid (HOCl) in solution to form monochloroamine (NH2Cl) as follows:

NH3 + HOCl > NH2Cl + H2O

The rate law for this reaction is:

d[NH3]/dt = -k[HOCl][NH3]

a) what is the reaction order with respect to NH3?

b) What order is this reaction overall?

c) If the HOCl concentration is held constant and equals10^-4 M, and the rate constant equals 5.1 x 10^6 L/moles-s, calculate the time required to reduce the concentration of NH3 to one half its original value.

Which reaction type is each chemical reaction, Precipitation, Acid-base, or Oxidation-reduction(redox)

1. CuSO₄(aq)+Ba(ClO₄)₂(aq)-->BaSO₄(s)+Cu(ClO₄)₂(aq)

2. 4Mn²⁺+5BiO^-₃(aq)+2OH^-(aq)-->H₂O(I)+4MnO^-₄(aq)+5Bi⁺(aq)

3.NH₄OH(aq)+HCl(aq)-->H₂O(l)+NH₄Cl(aq)

4. H₂C₂O₄+2NaOH(aq)-->H₂O(l)+Na₂C₂O₄(aq)

5. MgCl₂(aq)+Pb(NO₃)₂(aq)-->PbCl₂(s)+Mg(NO₃)₂

6. 4Zn(s)+NO^-₃(aq)+7H₂O(l)-->4Zn²⁺(aq)+NH⁺₄(aq)+10OH^-(aq)

7. Hg₂(OOCCH₃)₂(aq)+SrI₂(aq)-->Hg₂I₂(s)+Sr(OOCCH₃)₂(aq)

8.2HCl(aq)+K₂S(aq)-->H₂S(g)2KCl(aq)

9. 2H₃PO₄(aq)+3Ca(OH)₂(aq)-->3H₂O(l)+Ca₃(PO₄)₂(aq)

10. 4Fe(s)+3O₂(g)-->2Fe₂O₃(s)

Given the above standard free energies of formation at 25oC in kJ/mole,

(a) Find ΔGo and the equilibrium constant Kp for the reaction CO (g) + H2O (g)CO2 (g) + H2 (g) at 25oC

(b) Find the vapor pressure of H2O (g) at 25oC.

(c) If CO (g) , CO2 (g) and H2 (g) are mixed so that the partial pressure of each is 1.00 atm and the mixture is brought into contact with excess liquid H2O, what will be the partial pressure of each gas when equilibrium is attained at 25oC? The volume available to the gases is constant.

K_p = 6.5 × 10⁴ at 308 K for the following reaction:

2 NO (g) + Cl₂(g) ⇌ 2 NOCl(g)

At equilibrium,  P_NO = 0.35 atm and P_Cl2 = 0.10 atm

What is the equilibrium partial pressure of NOCl(g)?

Given the following equilibrium system:

2SO₂(g) + O₂(g) ↔ 2SO₃(g) + 99.1 kJ

If additional SO₂(g) is added to the system while the temperature and pressure are kept constant. Compared to its original concentration, how will the concentration, of oxygen change?
Increase
Decrease
Remain the Same

The pressure on the system is increased while the temperature is kept constant. Compared to its original concentration, how will the concentration of SO₂(g) change?
Decrease
Increase
Remain the Same

A catalyst is added to the above equilibrium system while the temperature and pressure are kept constant. Compared to its original concentration, how will the new equilibrium concentration of SO₂(g) change?
Remain the Same
Increase
Decrease

The temperature of the equilibrium system is decreased and the pressure is kept constant. Compared to its orginal concentration, how will the new equilibrium concentration of SO₂(g) change?
Remain the Same
Increase
Decrease