Gas chromatography questions

1. why is GC separation more efficient than a fractional distillation?

2. what characteristics must the liquid stationary phase have?

3. how do the flow rate of the carrier gad and the column temperature affect the retention time of a compound on a GC column?

4. Describe a method for identifying a compound using GC analysis

What is the concentration in % (v/v) of a methanol solution prepared by mixing 35.0 mL of methanol with 700 mL of distilled water?

Select a scientist, show how this person has contributed to our understanding of an area of science.

A solution of glucose (C₆H₁₂O₆) is prepared by dissolving 100.0 g of glucose in 1000. g of water. The density of the resultant solution is 1.050 g/mL. Kb for water is 0.52 ^oC/m and kf for water is –1.86 ^oC/m.

What is the vapor pressure of the solution at 100.0^oC?

What is the boiling point of the solution?

please i really need a clear explanation for this

What is the osmotic pressure of the solution at 25^oC?

When 15.0 mL of a 9.86×10-4 M magnesium sulfate solution is combined with 22.0 mL of a 6.62×10-4 M potassium carbonate solution does a precipitate form? yes (yes or no) For these conditions the Reaction Quotient, Q, is equal to

The Ka of propanoic acid (C2H5COOH) is 1.34 × 10-5. Calculate the pH of the solution and the concentrations of C2H5COOH and C2H5COO– in a 0.551 M propanoic acid solution at equilibrium.

Consider a 0.10 M solution of a weak polyprotic acid (H 2 A) with the possible values of K a 1 and K a 2 given below. Calculate the contributions to [ H 3 O + ] from each ionization step. Part A K a 1 =1.0× 10 −4 ; K a 2 =5.0× 10 −5 Express your answers using two significant figures separated by commas. [ H 3 O + ] 1 , [ H 3 O + ] 2 = Part B) I figured this one out. Part C K a 1 =1.0× 10 −4 ; K a 2 =1.0× 10 −6 Express your answers using two significant figures separated by commas. [ H 3 O + ] 1 , [ H 3 O + ] 2 =

Unit 6 Lab - Temperature Effects of Equilibrium

Photo Documentation

In order to earn full credit for the participation portion of this activity, you must submit at least 2 photos. Required photos are outlined in the procedure below.

Procedure

IMPORTANT SAFETY CONSIDERATIONS:

Avoid getting NaOH on your skin. Should you come in contact with this chemical, immediately wash with water. Review all MSDS associated with this lab.

Any broken or chipped glassware should be replaced.

Clean up spills immediately.

Create a buffer solution such that the pH=pKa, by adding half the amount of 1.00 M NaOH (prepared from the 6M NaOH provided in your kit) needed to reach the endpoint of 10 mL of vinegar.

This can be performed by titrating a 15.0 mL aliquot of vinegar with 1.00 M NaOH

Record the endpoint volume of NaOH

Add half the endpoint volume of NaOH to another 15.0 mL aliquot of vinegar into the test tube

The solution created in the previous step is a buffer solution such that the pH=pKa

Place the test tube in the 600 mL beaker with enough warm tap water to cover the solution in the test tube.

Place the thermometer in the test tube. Read the temperature and adjust the water until the temperature is near 30°C. (Take a photo)

When the temperature has stabilized record the temperature. Remove the thermometer and insert the pH probe and record the pH.

Insert the thermometer into the test tube and add ice to the bath to lower the temperature by 5°C. (Take a photo)

Repeat steps 4 and 5 in 5°C increments until the solution reaches 10°C.

Download and record all the data in the table linked here: Data Analysis Table. You can also recreate the table and record the data in your lab notebook.

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Unit 6 Lab – Temperature Effects of Equilibrium

Data Analysis Table

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Unit 6 Lab - Temperature Effects of Equilibrium

Analysis

Reflect upon the question(s) below and record your response(s) in your lab notebook. Completion of this analysis will be beneficial as you prepare for the post-lab quiz.

Your instructor will notify you if submission of this analysis is required.

Calculate the data for all the columns in the table you downloaded/created during the procedure. Remember the pK_a = pH for these buffer solutions.

Plot the data for the last two columns on the right. Plot ln(K_a) on the y-axis and 1/T on the x-axis.

From the plot or from linear regression determine the slope of the best fit line.

From the slope determine the ∆H° for this reaction.

∆H°=_______________________________________________

Was the value of ∆H° what you expected (i.e. exothermic/endothermic)? Explain.

What is the effect on the equilibrium when the temperature is changed? How is this related to ∆H°?

Which of the following is generally true regarding the impact of the reduced speed limit?

Calculate the molar mass of each Compound :
Gycerol
NaCl
CaCl
This is for the lab experiment on Molar Mass and freezing point, and these are the results l got.
Solution. Freezing point in degreesC
H2O. 0
Gycerol. -3.5
NaCl. -5.7
CaCl. -4.0
How do these molar masses compare to the theoretical. Calculate the percent error. glycerol I have 0.04470, and 0.0383 for NaCl and 0.01792 for CaCl. I know there is a constant l am supposed to use to get the theoretical molar mass, but l am stuck. CALCULATE THE PERCENT ERROR.

1. A [a]ml aliquot of a nitric acid of unknown concentration is pipetted into 125-ml Erlenmeyer flask and 2 drops of phenolphthalein are added. The [b] ml of sodium hydroxide with concentration [c]mol/l is used to titrate the nitric acid solution. What is the molar concentration (mol/l) of the nitric acid solution?

   For [a], [b], and [c] each student would have a different set of data. Practice how to solve this problem if [a] =20.00ml of nitric acid, [b] =17.60ml of NaOH, and [c] =0.1092M NaOH.

2. A [a] mL volume of an H2A acid solution of unknown concentration with 2 drops of phenolphthalein required [b] mL of [c] M NaOH to reach the endpoint. What is the molar concentration of the acid solution?
   [a]= 22.51ml

   [b]=24.62ml [c]=0.1201 M NaOH

3. A 0.200-g sample of impure NaOH required 18.25ml of 0.2406 M HCl for neutralization. What is the percent of NaOH in the sample? Show your work.

A mixture of propionic and n-butyric acids, which can be assumes to form ideal solutions, is to be separated by distillation a distillate containing 95 mol% propionic acid and a bottoms of 98 mol% n-butyric acid. Determine the type of condenser and estimate the distillation operating pressure. The normal boiling point for propionic acid is 141 C and n-butyric is 163.5 C.

a 5.00 g sample of TNT (C7H5N2O6) is burned in a bomb calorimeter with a heat capacity of 420 J/degreeC. The calorimeter contained 610 grams od water (4.18J/gdegreeC) and the temperature of the water was measured to go from 20.0 degree C to 22.5 degree C. What is the heat of combustion of TNT?.

I know the answer, but can you give me a step by step explanation of how to get it?

The fluorocarbon compound C2Cl3F3 has a normal boiling point of 47.6 ?C. The specific heats of C2Cl3F3(l) and C2Cl3F3(g) are 0.91 J/g?K and 0.67 J/g?K, respectively. The heat of vaporization for the compound is 27.49 kJ/mol.

Calculate the heat required to convert 46.0g of C2Cl3F3 from a liquid at 11.10?C to a gas at 81.20?C.