Ethyl alcohol (C2H5OH) burn in dry air according to the reaction

C2H5OH+2.16(O2+3.76N2)=0.32CO2+1.68CO+3H20+*.1216N2

determine the

a) Air-fuel ratio on a mass basis

b) equivalence ratio

c) Percent theoretical air

3. A 10.1-mL volume of a 0.00940 M KMnO4 solution was used to reach the stoichiometric point in the titration of 0.1040 g of an unknown sample containing oxalate ion.

a. Calculate the moles and mass of C2042- in the sample.

b. Determine the moles and mass of 02042- that would be present in a 100 g sample.

The average human body contains 5.00 L of blood with a Fe2+ concentration of 2.10×10^−5 M . If a person ingests 5.00 mL of 14.0 mM NaCN, what percentage of iron(II) in the blood would be sequestered by the cyanide ion?

Colligative Properties & Osmotic Pressure

Peter Jeschofnig, Ph.D. Version 42-0149-00-01

Lab Report Assistant                                                                                            

This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment�s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate student�s writing of lab reports by providing this information in an editable file which can be sent to an instructor

Observations & Questions for Part 1                                                              

Record your observations and your time and temperature data in tables. Use one table for the pure water and one table for the salt solution.                                                                                        

Make two graphs of your data. On one graph plot the data from the pure water. On the other graph plot the data from the salt solution. On both plot temperature on the y-axis and time on the x-axis.

A. Record the freezing point of the pure water and the freezing point of the salt solution.

Freezing point of salt Sol: -2 degree Celsius

Freezing point of pure H2O: 0 degree Celsius

B. How do these two freezing points compare?

The freezing point of salt water is lower than the freezing

point of fresh water. Salt in the water lowers the freezing point

of water.

C. What are some practical applications of freezing point depression, boiling point elevation, and vapor pressure lowering?

                                                            Some practical applications of freezing point depression

                                        are antifreeze in a radiator and salt on the road used to melt

                                        ice in the winter. Some practical applications of boiling point

                                        elevation are a sealed container and possibly a pressure cooker.

                                        Some practical applications of vapor pressure lowering are freeze

                                        drying and steam engines.

Questions - Part 2                                                                                                  

To what biological structure is the dialysis bag comparable? How is it similar? How is it different?

The plasma membrane is comparable to the dialysis bag.

The similarity between them is that they are both semipermeable.

The difference is the dialysis bag acts as a permeable membrane,

                                        however, purely based on its pore size, the small molecules are

                                        able to get through but the bigger molecules are unable to. The

                                        plasma membrane is a more complex system that uses both active

                                        and passive transport to allow the molecule to move through.

In biological systems if a cell is placed into a salt solution in which the salt concentration in the solution is lower than in the cell, the solution is said to be hypotonic. Water will move from the solution into the cell, causing lysis of the cell. In other words, the cell will expand to the point where it bursts. On the other hand, if a cell is placed into a salt solution in which the salt concentration in the solution is higher than in the cell, the solution is said to be hypertonic. In this case, water will move from the cell into the solution, causing cellular death through crenation or cellular shrinkage. In your experiment is the Karo� hypertonic or hypotonic to the egg?

The Karo is hypertonic to the egg, because during the 24

hours, the egg started to float on top of the Karo syrup

and there was water loss.

C. Historically certain colligative properties � freezing point depression, boiling point elevation, and osmotic pressure � have been used to determine molecular mass. (Now there are instrumental methods to determine this.) Of these three, osmotic pressure is the most sensitive and gives the best results. Molecular mass can be found according the following equation:

? = MRT

Where:                  ? = osmotic pressure,

M = molarity of solution,

R = the ideal gas constant (0.0821 L�atm/mol�K), and

T = Kelvin temperature.

Sample Problem

0.125 grams of a starch is dissolved in 100 mL of water at 25oC and has an osmotic pressure of

5.15 mmHg. What is its molecular mass?

Since the gas constant, R, requires atmospheres as pressure units, we have to convert 5.15 mmHg to atmospheres:

5.15 mm Hg * 1 atm/760 mm Hg = 0.00678 atm.

0.00678 atm = M (0.0821) (273 + 25 = 298 K); We solve for M = 0.00678/(0.0821*298);

M (molarity) = 2.77 x 10 �4

Molarity = moles/L: 2.77 x 10�4 = moles/.1 = 2.77 x 10-5 moles of starch; If 2.77 x 10-5 moles = 0.125 grams,

Then 1 mole = 0.125 g/2.77 x 10-5 = 4512 g/mole = molar mass of starch.

Problem for Lab Report:

At 23.6�C, 0.500 L of a solution containing 0.302 grams of an antibiotic has an osmotic pressure of 8.34 mmHg. What is its molecular mass?

8.34 mmHg(1atm/760 mmHg)

=0.010974 atm

0.010974 atm/ (0.0821L.atm/K.mol)(296.6K)

=0.000451 mole/L

0.500L(0.000451 mole/L)

=0.000225

=0.302 gr/0.000225

=1342.22g/mol

                                        The molecular mass is 1342.22 g/mol.

So after I completed this lab, I was asked the following question:

What changes would you make, if any, if you did this lab again? Include a discussion of differences between the individual data sets

Butyric acid is responsible for the foul smell of rancid butter. The pK_a of butyric acid is 4.84.

(a) Calculate the pK_b for the butyrate ion.

(b) Calculate the pH of a 0.048 M solution of butyric acid.

(c) Calculate the pH of a 0.048 M solution of sodium butyrate.

1/ Determine the amount of heaat required to raise the temperature of 2500 grams of water form 35C degree to 57C degree. The specific heat of water is 4.18J/g*C.

2/A system releases 350. kilojoules of heat while 750. kilojoules of work are done on it. Determine the change in internal energy (△ E) of the system

3/ Afixed mass of gas is placed in a cylinder fitted with a movable piston. 2000.joules of heat are added to the gas, causing it to expand. The expanding gas caused the piston to rise, thus increasing the volume of the cylinder 4,5 liters. If the constant downward pressure of the piston on the gas was 3.5 atmospheres.Calculate the (△ E) of the gas.

4/ How many joules of heat are released to the surroundings when145.0 grams of aluminum react with an excess amount of iron(III) oxide according to the following reaction?

2AL + Fe2O3 ------> AL2O3 + 2Fe △Hrxn= -849KJ

5/ use the following reactions 1,2 and 3 to determine the enthalpy of reaction for:

N2O(g) + NO2(g) -----> 3NO(g) △Hrxn= ?

I/ N2(g) + O2 (g) ------> 2NO(g) △Hrxn=+180.7KJ

II/ 2NO(g) + O2(g) ------> 2NO2(g) △Hrxn=-113.1KJ

III/ 2N2O(g) ------> 2N2(g) + O2(g) △Hrxn=-163.2KJ

6/ A 75 gram piece of copper at 100C degree is placed in an insulated container that contains 225 grams of water at 35C degree. Determine the equilibrium temperature reached in the copper water system. The specific heat of copper is 0.385J/g*C and the specific heat of water is 4.18J/g*C. You may assume that there is no exchange of heat between the system and surroundings.

30lb of coal (83%Carbon, 1%Sulfur, 12%Hyrdogen and 4%H20) are burned with 600lb of air yielding a gas in which ratio of CO2 to CO is 3 to 2. What is the mole percent of each component in the flue gas

What is the primary molecular level difference between a ceramic and a glass material?

How does increasing porosity of a bioceramic material influence the biodegradation rate?

The bioactivity of Bioglass 45S5 is due to what three chemical species?

Show the first five reaction steps in the formation of the hydroxyl-carbonate-apatite (HCA) layer upon dissolution of Bioglass 45S5 in biological media.

Finding cconcentration from Ksp, advanced topics in chemistry.

Find the concentration of I- in 0.0010 M AgNO3 saturated with AgI. In clude aciticity coefficients in your solubility-product expresion. The Kap od AgI is 8.3 x10 -17.

Ans is not:

1.03 x10 -13

9.44 x10 -9

8.3 x 10-14

8.135 x 10 -14

1.028 x10 -13

1.028 x 10 -14

You have a 30.0L cylinder of helium at a pressure of 132 atm and a temperature of 19 Celcius. The Hlium is used to fill a balloons to a volum of 1.80L at 145mmHg and 27 Celcius.

How many baloons can be filled with He? (Assume that the cylinder can provide He until its internal pressure reaches 1.00 atm. i.e., there are 131 atmospheres of usable He in the cylinder) Show all your work with units.

Please help. Thank you so much!

Calculate the following: (Show all work)

(a) the unit cell volume of lead (FCC), assuming an atomic radius of 0.175 nm.

(b) the radius of a palladium (FCC) atom, given that its density is 12 g/cm3 and atomic weight is 106 g/mol.

(c) Calculate and compare the planar density of (100) and (111) planes for FCC structure

Draw the structure of aspirin. Circle and name the functional group with makes aspirin an acid.

The diffusion coefficients for carbon in nickel are given at two temperatures:

(a) Determine the value of D_0.
(b) Determine the value of Q_d.
(c) What is the magnitude of D? at 880˚C?

The following questions refer to the gas phase decomposition of ethylene chloride

C2H5Cl→ products

Experiment shows that the decomposition is first order. The following data show kinetics

information for this reaction.

Time (s)               1.0       2.0

ln [C2H5Cl] (M)    -1.625    -1.735

What is the rate constant for this decomposition if [C2H5Cl] is 0.20M?

What was the initial concentration of the ethylene chloride? K=0.12

What would the concentration be after 4.0 seconds? based on previous question

An aqueous solution of potassium hydroxide has a concentration of 0.372 molal.

The percent by mass of potassium hydroxide in the solution is _______%.

An aqueous solution is 22.0% by mass silver nitrate, AgNO₃, and has a density of 1.22 g/mL.

The molality of silver nitrate in the solution is _______m.