Erioglucine is a blue­colored dye that absorbs its complementary color, red, in aqueous solution around 645 nm. Unfortunately, the local distilled water supply is consistently contaminated with a trace amount of a metal cation that also absorbs 645 nm light. Suppose then, a control sample of 0.0552 M erioglucine (aq; same water supply) has an absorbance of 0.331 and that a distilled water sample in a similar cuvette has an absorbance of 0.019. Determine the concentration of an erioglucine (aq) sample (same water supply) that has an absorbance of 0.237. Concentration: _____ M

Professor Van Eggmon thinks that dissolving eggshells at 74.1o F is easier than cracking eggs. The shells are made of calcium carbonate (CaCO3), which reacts with acetic acid (CH3COOH) to form carbon dioxide (CO2), water (H2O), and calcium acetate (Ca(CH3COO)2). The feed to the egg dissolver (reactor) contains 46.2 mol/s calcium carbonate and 352 mol/s dilute acetic acid solution (4.15 mol% acetic acid and the balance water). The conversion of acetic acid is 69.4%. a. (5 points) Draw and label a process flow diagram. Number the streams and clearly label the components in each stream. b. (3 points) Write the limiting reactant in the box. c. (34 points) Determine the component flow rates (mol/s) exiting the reactor. d. (3 points) Find the temperature in Kelvin (K). e. (3 points) The professor’s children state that the feed flow rate of CaCO3 of 9.43 x 107 g/day. Compared to the original operating conditions, the feed flow rate of CaCO3 will (circle one): INCREASE DECREASE STAY THE SAME

You are given a sample that has 1.3 mg/ml of purified protein. The molecular weight is 37,000 Daltons.

a) the absorbance in a 1cm cuvette is 0.93. calculate the molar extinction coefficient. Be sure to express your answer with correct units.

b)also calculate the extinction coefficient for concentration units of mg/ml, i.e. with units of cm^-1 (mg/ml)^-1

c) The sample is actually contaminated with 0.01 mg/ml DNA, but the protein concentration, 1.3 mg/ml is correct. explain how the contaminating DNA will affect your estimate of the extinction coefficient?

d) suggest a way in chich you could salvage this situation without doing any more experiments. that is, explain how you could estimate the extinction coefficient in spite of teh DNA contamination. what key inormation would you need to look up on the internet or in the library? carefully explain how you would calculate the extinction coefficient.

this is what I have done so far:

a) A=CLε

ε=0.93/(1.3mg/ml)*1cm

=.715(mg/ml)^-1Cm^-1

=.715(cm^-1) (ml/mg)(1L/1000ml)(1000mg/g)(37000g/mol)=26469(L/mol)=26469M^-1cm^-1

b) 26469M^-1cm^-1=26469cm^-1(L/mol)(1000ml/L)(1mol/37000g)(1g/1000mg)=.715(ml/mg)cm^-1=.715(mg/ml)^-1cm^-1

c) this would increase the absorbance, so it would make the extinction coefficient too high

d) ?

You wish to dissolve benzaldehyde, a liquid at 25 degrees celsius, in an appropriate liquid solvent. Which of the following substances would probably be the best choice for a solvent at that temperature? Cyclohexane, cyclohexene, benzene, or octane. Please Explain why

1) What is/are the spectator ion(s) for the following chemical reaction? Check all that apply.

Pb(NO3)2(aq) + Na2S(aq) --> PbS(s) + 2 NaNO3(aq)

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Question 2

What is the driving force of reaction 4B?

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Question 3

Predict the products of the following reaction:

Mg(s) + HCl(aq) -->

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Question 4

NaClO is commonly used as bleach. The following is a sample reaction of NaClO. What is the oxidizing agent in this reaction?

3 NaClO + H2S --> 3 NaCl + H2O + SO2

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Question 5

When colorless Ba(NO3)2 solution mixes with colorless Na2SO4 solution:

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Question 6

A test tube has a colorless aqueous layer of NaI solution and an colorless organic layer of methylene chloride. When a few mL of colorless chlorine water is added to this test tube. The organic layer became pink. What is causing this pink color in the organic layer?

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Question 7

Which of the following has the lowest concentration of H+?

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Question 8

What is the oxidation state of N in AgNO3?

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Question 9

A water sample with unknown mass absorbed 100.0 J of heat and the temperature increased from 25.0 C to 29.8 C. What is the mass of this water sample? Specific heat of water = 4.184 J/(gC).

Note: To avoid any sig fig issues, please keep only two sig figs for your input!!

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Question 10

Which one is correct about the following process?

CH4 + 2 O2 --> CO2 + 2 H2O

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Question 11

100.0 mL of 1.00 mol/L NaOH reacted with 65.4 mL of 1.00 mol/L CH3COOH solution and the temperature increased from 20 to 22 C. How many moles of NaOH get and CH3COOH are neutralized?

Note: to avoid any sig fig issues, please use regular decimal instead of scientific notation and keep 3 sig figs for your input!!

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Question 12

At room temperature, H2SO4 is dissolved in water and the solution is much hotter. So the dissolution of H2SO4

Decide if the compound/ion listed can satisfy the octet rule (duet rule for H), if so choose Satisfies Octet Rule from the drop down menu. If the compound/ion cannot satisfy the octet rule for one of the atoms in the formula, choose one of the following three reasons why; Too many valence electrons (more than eight), Too few valence electrons (fewer than eight), or Odd # of valence electrons. CCl3 NO3- ICl3 SF3 PCl3 PS3

The Ka of a monoprotic weak acid is 5.13 × 10-3. What is the percent ionization of a 0.179 M solution of this acid?

Record your values for ΔHA and ΔHB below: Mg (s) + 2 HCl (aq) → MgCl2 (aq) + H2 (g) ∆HA = __-4.70 x 105 kJ/mol Mg_ MgO (s) + 2 HCl (aq) → MgCl2 (aq) + H2O (l) ∆HB = __-150 kJ/mol MgO___ _ In order to calculate the heat of formation of MgO (∆Hf MgO), you will also need one additional enthalpy value, the enthalpy of formation of liquid water. Look this value up in a textbook and record it below. Be sure you record the value for liquid water, not gaseous water. H2 (g) + ½ O2 (g) → H2O (l) ∆Hf = _-285.8 kJ/mol__ Calculations: Show all of your work, with units. Record answers with correct significant figures. 1. Using the information determined above and Hess’s Law, the heat of formation (∆Hf) for MgO can be obtained. Rearrange the three equations above to determine H for: Mg (s) + ½ O2 (g)  MgO (s): show your work, and pay attention to sig figs! Mg (s) + ½ O2 (g) → MgO (s) H2 (g) + ½ O2 (g) → H2O (l) Your value for ∆Hf MgO(pay attention to sig figs!) = __________________ 2. Look up the theoretical (textbook) value for the heat of formation of MgO and calculate your percent difference to the correct significant figures. Textbook value for ∆Hf MgO = __-601.6__ kJ/mol % difference = ____________________

Dolomite, [CaMg(CO3)2] is found in a soil sample. A geochemist titrates 24.65 g of soil with 57.85 mL of 0.3315M HCl. What is the mass % of dolomite in the soil? ( Write answer to two decimal places, ex. 15.77) Following is the acid/base reaction which occurs during the titration: CO3-2(aq) + HCl(aq) --> HCO3-(aq) + Cl-(aq)

A buffer with a pH of 4.06 contains 0.13 M of sodium benzoate and 0.18 M of benzoic acid. What is the concentration of [H ] in the solution after the addition of 0.052 mol of HCl to a final volume of 1.3 L? Assume that any contribution of HCl to the volume is negligible.

mass of empty beaker-----------132.862 g

mass of beaker with unknown sample--------133.343g

ass of crucible------------41.962g

mass of crucible with BaSO4---------------42.631g

A) calculate the number of moles of BaSO4 that were collected

B) calulate the number of moles of SO4^2- ion that were in the unknown

C) calulate the mass of the sulfate ion in the unknown

D) calculate the mass percentage of the sulfate ion in the unknown sample.

In the laboratory, a general chemistry student measured the pH of a 0.550 M aqueous solution of formic acid, HCOOH to be 1.987.

Use the information she obtained to determine the K_a for this acid.

K_a(experiment) =

4. An ideal gas in a moveable piston is allowed to reversibly expand by slowly heating at constant pressure.

a. (10 pts) Derive the equation for the work done (w reversible) as a function of the initial and final temperatures.

b. (10 pts) Derive the equation for the change in heat in the system (q).

c. (10 pts) Derive the equation for the change in entropy.

2. A 1.00L piston with 1.00mole of an ideal gas at 298.0K and 1.00bar is isothermally and reversibly compressed to a final volume of 0.100L, then irreversibly expanded in 1 step to its original volume with an applied pressure of 1.00bar.

a. (6 pts) Calculate the change in heat for the system (q sys) for the compression and expansion steps.

b. (6 pts) Calculate the change in entropy for the compression and expansion steps.

Show step by step and i will rate!

Thanks!

c. (6 pts) Calculate the net change in entropy for the compression and expansion steps together.

d. (6 pts) Is there a net change in entropy for the system? If so, why; if not, why not?

e. (6 pts) Is there a net change in the entropy for the surrounding? If so, why; if not, why not?