How much ice (in grams) would have to melt to lower the temperature of 355 mL of water from 26 ∘C to 6 ∘C? (You must consider the enthalpy in cooling the water, as well as the enthalpy in melting the ice and the enthalpy to heat the melted ice from 0∘C up to the system's final temperature of 6 ∘C. Also assume that the density of water is 1.0 g/mL.) Express your answer using two significant figures.
In: Chemistry
What functional groups are in a receptor? Does the benzene ring in a drug or adrenaline form a hydrophobic interaction in a receptor?
In: Chemistry
Two kg of water exist initially as a vapor and liquid at 90°C in
a rigid container of volume 2.42 m3.
(a)At what pressure is the system?
(b)What is the quality of the system?
(c)The temperature of the container is raised to 100°C. What is the
quality of the system, and what is the pressure? What are ΔH and ΔU
at this point relative to the initial state?
(d)As the temperature is increased, at what temperature and
pressure does the container contain only saturated vapor? What is
ΔH and ΔU at this point relative to the initial state?
(e)Make a qualitative sketch of parts (a) through (d) on a P-V
diagram, showing the phase envelope.
In: Chemistry
How much heat energy, in kilojoules, is required to convert 32.0 g of ice at −18.0 ∘C to water at 25.0 ∘C ? Express your answer to three significant figures and include the appropriate units.
How long would it take for 1.50 mol of water at 100.0 ∘C to be converted completely into steam if heat were added at a constant rate of 25.0 J/s ?
Express your answer to three significant figures and include the appropriate units.
In: Chemistry
A student was given an old tablet of vitamin C weighed 1.022 g to analyze. The tablet was dissolved in 700.0 mL water, and 35.0 mL aliquot of this solution required 45.6 mL of unknown molarity I2 (stock A) solution to oxidize it. In another experiment, the student titrated 50. mL of that same I2 (stock A) with 17.6 mL of 0.0100 M ascorbic acid. Calculate the mg vitamin C in the tablet.
In: Chemistry
Clausius inequality: working with a cycic path shown and using his own result, clausius concluded that in an isolated system entropy increases . Can you prove the same as well?
In: Chemistry
Determine the empirical and molecular formulas of each of the following substances
Part A
Ibuprofen, a headache remedy, contains 75.69% C, 8.80% H, and 15.51% O by mass, and has a molar mass of 206 g/mol.
Express your answers as chemical formulas separated by a comma.
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Part B
Cadaverine, a foul smelling substance produced by the action of bacteria on meat, contains 58.55% C, 13.81% H, and 27.40% N by mass; its molar mass is 102.2 g/mol.
Express your answers as chemical formulas separated by a comma.
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Part C
Epinephrine (adrenaline), a hormone secreted into the bloodstream in times of danger or stress, contains 59.0%C, 7.1% H, 26.2% O, and 7.7% N by mass; its MW is about 180 amu.
Express your answers as chemical formulas separated by a comma.
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In: Chemistry
1) 1. How many ATOMS of
sulfur are present in 4.30 moles
of sulfur dioxide ?
atoms of sulfur.
2. How many MOLES of
oxygen are present in
1.91×1022 molecules of sulfur
dioxide ?
moles of oxygen.
2) 1. How many MOLECULES of
carbon tetrafluoride are present in
1.45 moles of this compound ?
molecules.
2. How many MOLES of
carbon tetrafluoride are present in
1.07×1023 molecules of this compound
?
moles.
3) 1. How many MOLECULES of
phosphorus triiodide are present in
2.80 moles of this compound ?
molecules.
2. How many MOLES of
phosphorus triiodide are present in
1.08×1023molecules of this compound
?
moles.
3) 1. How many ATOMS of
sulfur are present in 8.41 grams
of sulfur dioxide? atoms of
sulfur .
2. How many GRAMS of
oxygen are present in
1.91×1022 molecules of sulfur
dioxide ? grams of oxygen
4) 1. How many
MOLECULES of carbon tetrafluoride
are present in 1.91 grams of this compound
? molecules.
2. How many GRAMS of
carbon tetrafluoride are present in
1.07×1023 molecules of this compound
? grams.
5) 1. How many MOLECULES of
phosphorus triiodide are present in
4.98 grams of this compound
? molecules.
2. How many GRAMS of
phosphorus triiodide are present in
1.08×1023molecules of this compound
? grams.
6)
What is the mass of a sulfur dioxide molecule
?
grams
7)What is the mass of a carbon tetrafluoride
molecule ?
grams
8)What is the mass of a phosphorus triiodide
molecule ?
grams
9)1. How many GRAMS of
sulfur are present in 4.30 grams
of sulfur dioxide ?
grams sulfur.
2. How many GRAMS of
sulfur dioxide can be produced from
1.69 grams ofoxygen ?
grams sulfur dioxide.
10)1. How many GRAMS of
cobalt(II) are present in 1.36
grams of cobalt(II) sulfite ?
grams cobalt(II).
2. How many GRAMS of
cobalt(II) sulfite can be made from
4.90 grams ofcobalt(II) ?
grams cobalt(II) sulfite.
11)1. How many GRAMS of
chromium(II) are present in 2.74
grams ofchromium(II) chloride ?
grams chromium(II).
2. How many GRAMS of
chromium(II) chloride can be made from
4.92 grams ofchromium(II) ?
grams chromium(II) chloride.
In: Chemistry
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(a) when 1/2N2(g)+3/2H2(g)?NH3(g) for NH3(g) find the value of ?H?f. |
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(b) when S(s)+O2(g)?SO2(g) |
For SO2(g) find the value of ?H?f.
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(c) when Rb(s)+12Cl2(g)+32O2(g)?RbClO3(s) |
For RbClO3(s) find the value of ?H?f.
In: Chemistry
Synthetically produced ethanol is an important industrial commodity used for various purposes, including as a solvent (especially for substances intended for human contact or consumption); in coatings, inks, and personal care products; for sterilization; and as a fuel. Industrial ethanol is a petrochemical synthesized by the hydrolysis of ethylene:
C2H4 (g) + H2O (v) <=>C2H5OH (v)
Some of the product is converted to diethyl ether in the undesired
side reaction:
2 C2H5OH (v)<=> (C2H5 )2O (v) + H2O (v)
The combined feed to the reactor contains 53.7 mole% C2H4, 36.7% H2O, and the balance nitrogen, and enters the reactor at 310oC. The reactor operates isothermally at 310oC. An ethylene conversion of 5% is achieved, and the yield of ethanol (moles ethanol produced/moles ethylene consumed) is 0.900. Hint: treat the reactor as an open system.
Data for Diethyl Ether:
ˆ
H of = -271.2 kJ/mol for the liquid
ˆ
Hv = 26.05 kJ/mol (assume independent of T )
Cp[kJ/(molC)] = 0.08945 + 40.33*10-5T(C) -2.244*10-7T2
(a) Calculate the reactor heating or cooling requirement in
kJ/mol feed.
(b) Why would the reactor be designed to yield such a low
conversion of ethylene? What processing
step (or steps) would probably follow the reactor in a commercial implementation of this process?
In: Chemistry
Which of the following titrations results in a basic solution at the equivalence point? Select one:
A. NaCN titrated with HCl
B. HCl titrated with NH3
C. HCN titrated with NaOH
D. HCl titrated with NaOH
In: Chemistry
How does type of drying impact product quality? What are some pros and cons of each processing parameters (i.e. microwave, hot air, or freeze drying)?
How would compositional parameters of the food product effect drying?
What would be the effect of changing temperature of hot air drying?
How can you improve the rate of drying of a product in hot air convection oven set at a specific temperature?
In: Chemistry
You work in a small-scale manufacturing facility that uses phthalic acid as the starting material for a multi-step synthesis. Your company buys ~98% pure phthalic acid from a major manufacturer and purifies it in-house prior to its use in the multi-step synthesis. You are given the job to purify 50 g of the impure phthalic acid by recrystallization from water. Approximately how much water will you need to use to prepare the hot saturated solution? Upon cooling in an ice-bath, and subsequent filtration, how much pure phthalic acid would you expect to recover?
In: Chemistry
Compare and contrast the BCA and Bradford methods for protein concentration determination. How does each work? Give an example of something that interferes with these methods and explain where each works better than the other. Be as specific as possible.
In: Chemistry
You want to maintain pH = 7.0 for an enzyme-catalyzed reaction that will produce hydrogen ions along with the desired product. At equal concentrations, which weak acid, if any, will serve as the better buffer for the reaction: Acid A pKa = 6.5, Acid B pKa = 7.5
a. Acid A
b. both are equally effective
c. water is as good as either of the acids available
d. acid B
*** I get that answer A is correct but Wouldn't B (pKa = 7.5) be better because as more H+ gets released by the reaction the pH would go down closer to 7, while if A was used the pH would fall further away from 7 . Also I'm not sure what is at "equal concentrations" as in the question
In: Chemistry