Give me two reasons for deviations from Beers’ law that would cause a nonlinear relationship
between absorbance and concentration. Explain why the deviations from linearity occur.?
In: Chemistry
15.7 g of H2 gas is mixed with 294 g of I2 gas in a 5.00 L tank at 25 ºC. The two gasses react to form hydrogen iodide gas by the reaction H2(g)+I2<->2HI(g). Given K=710 at ºC, what are the equilibrium concentrations of each gas? (Answers are listed in order of [H2], [I2] and [HI].)
a.1.560, 0.230, 0.000 b.0.000, 1.560, 3.120 c.1.330, 0.000, 0.460 d.1.328, 0.000230, 0.464
In: Chemistry
a start up company is trying to produce its own brand of antibacterial ointment. it decides to analyze a generic brand already on the market so that it can make suitable modification to the chemical composition. its known that the generic ointment contain benzoic acid( active ingredient), benzhydrol (the fixative) and anise, which add fragrance. you are a part of development team that wishes to separate these three substances in order to determine their relative proportions in the ointment, as well as to discover any inactive or unlisted constituents. some member of your team were able to isolate the inactive ingredient; However, NMR reveals that you still have a mixture of benzoic acid, benzhydrol, anisole left unseparated. as a member of team, you have been asked to do the following: 1. design an experiment to separate the following compounds from a mixture using any combination of purification techniques (TLC, column chromatography, Extraction and recrystallization) 2. carry out characterization studies such as melting point, IR, NMR to confirm that your purification was successful. 3. determine the percent recovery of the individual components of the mixture. mixture originally contained; 0.5g benzoic acid, 0.25g benzhydrol, 0.25ml anisole and 10ml diethyl ether.
In: Chemistry
In: Chemistry
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
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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?
In: Chemistry
Select a scientist, show how this person has contributed to our understanding of an area of science.
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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 100.0oC?
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 25oC?
In: Chemistry
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
In: Chemistry
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.
In: Chemistry
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 =
In: Chemistry
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
pH |
T (°C) |
Ka |
T(K) |
ln(Ka) |
1/T (K-1) |
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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 pKa = pH for these buffer solutions.
Plot the data for the last two columns on the right. Plot ln(Ka) 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°?
In: Chemistry
Which of the following is generally true regarding the impact of the reduced speed limit?
(a) It always reduces the atmospheric emissions from vehicles |
||
(b) Whether it reduces the emission depends on the types of fuels (e.g., gasoline vs. diesel) |
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(c) Whether it reduces the emission depends on the types of pollutants (e.g., CO, HCs, NOx, PM) |
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(d) both (b) and (c) |
In: Chemistry
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.
In: Chemistry
In: Chemistry