a sample aqueous solution of iron(iii) sulfate has a mass of 200g, a density of 1.05 g/cm^3 and 8.35 x10^21 atoms of sulfur. What is the molarity of the solution?
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Microwaves are a type of radio waves. Microwave ovens typically use microwaves with a wavelength of 12 cm. They are able to heat foods because water molecules absorb the energy of the microwave photons. If you heat a cup of water from 25°C to 100°C, how many microwave photons, on average, hit each molecule of water while it is being heated?
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32P is a radioactive isotope with a half-life of 14.3 days. If you currently have 30.9 g of 32P, how much 32P was present 9.00 days ago?
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How many different glycosides can be formed by linking one D-glucopyranose and one D-galactopyranose? Explain your reasoning.
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An environmental chemist working for the Environmental Protection Agency (EPA) was directed to collect razor clams from a heavily-contaminated river superfund site and analyze them for cadmium (Cd2 ) content using graphite furnace atomic absorption spectrometry (GFAAS). The chemist dried the clams at 95° C overnight and ground them in a scientific blender, resulting in ~ 50 g of homogenized dry weight. A representative 64.00 mg sample was taken from the ~ 50 g of dry material and dissolved in 100.00 mL of 0.1 M HCl to create a sample solution. Using the method of standard additions, the chemist prepared five standard solutions in 100.00-mL volumetric flasks, each containing 5.00-mL aliquots of the sample solution. Varying amounts of a 89.0 ppb (μg ·L-1) cadmium standard were added to each of the flasks, which were then brought to volume with 0.1 M HCl. The solutions were then examined for their Cd2 content using GFAAS, resulting in the following absorbance data.
Determine the amount of Cd2 per gram of dry clam. Express your final result as milligrams of Cd2 per gram of dry clam
|
Sample 5 |
cd2+ standard volume 0 |
absorbance 0.080 |
||
| 5 | 2.50 | 0.119 | ||
| 5 |
5 |
0.163 |
||
| 5 | 7.50 | 0.200 | ||
| 5 | 10 | 0.241 | ||
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Codeine (C18H21NO3) is a narcotic pain reliever titrated with HCL. What is the pH of a 0.0500 M codeine hydrochloride solution with a pKa of 5.80? Note the titrated form of codeine hydrochloride will act as a weak acid due to the formation of soluble ammonium salt.
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Hydrogen holds promise as an environment-friendly fuel. How many grams of H2 gas are present in a 54.0 L fuel tank at a pressure of 2501 lb/in2 (psi) at 20.0°C? Assume that 1 atm = 14.7 psi.
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The most important commercial process for generating hydrogen gas is the water-gas shift reaction: CH4(g) + H2O(g) ? CO(g) + 3H2(g)
?G° for this reaction at the standard temperature of 25°C is 1.423×102 kJ. Now calculate ?G°1150 for this process when it occurs at 1150 K.
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5.)Part B
Calcium sulfate, CaSO4, has a Ksp value of 7.10×10−5 . What happens when calcium and sulfate solutions are mixed to give 2.00×10−3M Ca2+ and 3.00×10−2M SO42−?
Calcium sulfate, , has a value of 7.10×10−5 . What happens when calcium and sulfate solutions are mixed to give 2.00×10−3 and 3.00×10−2 ?
| A.) | A precipitate forms because Q>Ksp. |
| B.) | A precipitate forms because Q<Ksp. |
| C.) | No precipitate forms because Q>Ksp. |
| D.) | No precipitate forms because Q<Ksp. |
6.)Part A
The addition of which of the following substances will not affect the existing equilibrium in a HF solution?
| a.) | KF |
| b.)HCl | |
| c.) | NaOH |
| d.) |
KCl |
7.)Part A
Calculate the pH of a solution that is 0.27 M in HF and 0.11 M in NaF.
Express your answer using two decimal places.
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when you would want to use collision theory over transition state theory and when you would want to use transition state theory over collision theory. Provide examples for both. Use literature citations to support your information. Follow the same formatting as requested in the group project reports.
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Which of the following buffer systems would be the best choice to create a buffer with pH = 9.00? HF/KF HNO2/KNO2 NH3/NH4Cl HClO/KClO
For the best system, calculate the ratio of the masses of the buffer components required to make the buffer. Express your answer using two significant figures.
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Comparison of Fresh and Sour Milk
pH of fresh milk:
pH of sour milk:
Which type of milk has the lower pH?
The greater acidity?
The greater H+ concentration. What organic (carboxylic) acid produces the H+ in sour milk? What is its source?
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(5)
Chloroacetic acid, HC2H2ClO2, has a greater acid strength than acetic acid because the electronegative chlorine atom pulls electrons away from the O-H bond and thus weakens it. Calculate the hydronium ion concentration and the pH of a 2.49E-3 M solution of chloroacetic acid. Ka is 1.3E-3.
[H3O+] = _____ M
pH = _____
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