A 54.3 mg sample of sodium perchlorate contains radioactive chlorine-36 (whose atomic mass is 36.0 amu).
If 29.6% of the chlorine atoms in the sample are chlorine-36 and the remainder is naturally occurring nonradioactive chlorine atoms, how many disintegrations per second are produced by this sample? The half-life of chlorine-36 is 3.0×105 yr.
My answer: 1.77x10^7
please explain steps, thank you!
In: Chemistry
25mL of acetic acid was placed in a 250mL flask and diluted using water to the mark (250mL) and mixed. 25mL of this solution is then placed into a seperate flask and titrated using 16.5mL of 0.106M NaOH. What is the molarity of acetic acid (M.W.= 60.05 g/mol)?
In: Chemistry
Procedure 1. A 25 mL round bottom flask equipped with a stir bar is loaded with 13 mg of CdO powder, 0.6 mL of oleic acid, and 10 mL of 1-octadecene. The reaction flask is placed into a heating mantle and surrounded with aluminum foil so that the temperature can reach 225 °C, which will take approximately 1 hr. Some hot plates may heat up faster and the experiment can be performed sooner. 2. As the CdO solution is heating, the Se solution should be prepared. Five students can share the Se solution, since only 1 mL is required for each reaction. A 25 mL round-bottom flask equipped with a stir bar is loaded with 30 mg of Se and 5 mL of 1-octadecene and allowed to stir at room temperature. To this stirred solution was added 0.4 mL of trioctylphosphine via syringe. The mixture will turn homogeneous. At this point it is ready for the next step. 3. Once the CdO solution has reached a temperature of about 225 °C, add 1 mL of the Se solution from step 2 in a rapid fashion. As soon as you add the Se solution start collecting samples of approximately 1 mL into separate test tubes continuously as the reaction will be changing colors from yellow to orange to blood red. 4. After allowing the quantum dot solutions to cool, add 1 mL of pentane to the test tube containing ~1 mL of sample. Then, pipette the samples into a glass cuvette to record their UV-Vis spectra. Use pentane as the blank. The solutions collected in test tubes can be stored overnight in the hood or drawer without decomposition if there is not enough time to record UV-vis spectra.
What reaction is occurring when the selenium dissolves after trioctylphosphine is added.
In: Chemistry
In: Chemistry
List at least one chemical reaction if possible of Melatonin.
In: Chemistry
Explain the main difference between the adsorption (initial) stage and ordering process (second stage) of Self=Assemble monolayer using the relevant chemical concepts, models and forces.
In: Chemistry
12. An electrolytic dissociation of water. The ionic
product of water. Hydrogen index. dissociation degree
(α) of the electrolyte as a quantitative description of the
equilibrium ionization process. The division
of electrolytes on the strengths and weaknesses of the value of the
degree of dissociation. Factors that
influence the degree of dissociation.
In: Chemistry
a) The solubility product for PbCl2 is 1.6 ∙ 10-5. The
solubility product for AgCl is 1.6 ∙ 10-10. How does the solubility
of lead chloride in a 0.10 M AgNO3 solution compare to the
solubility in pure water? Will it be higher, lower og not
changed?
Please explain your answer briefly as I dont get it.
b) The solubility of a salt MX is 1.1 ∙ 10-3 mol / L. What is the solubility product Ksp for the salt?
In: Chemistry
CAN YOU PLEASE EXPLAIN HOW TO DETERMINE METHOD I SHOULD USE TO FIND THE PH IN SUCH PROBLEMS. WHAT RULES SHOULD I FOLLOW OR THINK OF TO DETERMINE SUCH QUESTIONS. (STRONG ACID, STRONG BASE, BUFFER 1, BUFFER 2, WEAK ACID, WEAK BASE ETC)
PLEASE: dont solve if you dont explain briefly, and explain to me how I can determine it by myself.
The acid H2A has Ka1 = 2.00 ∙ 10-5 and Ka2 = 5.00 ∙ 10-9. We have a buffer consisting of 0.0300 moles of HA– and 0.0100 moles of A2– and adds 0.0500 moles of H3O +. What kind of system do we have and how to calculate the pH? Buffer 1 = H2A / HA– Buffer 2 = HA– / A2–
In: Chemistry
In: Chemistry
| Be sure to answer all parts. How many photons at 586 nm must be absorbed to melt 4.65 ×102 g of ice? (It takes 334 J to melt 1 g of ice at 0°C.) (Enter your answer in scientific notation.) |
In: Chemistry
|
Be sure to answer all parts. .........× 10^...... ( photons/J Enter your answer in scientific notation.) Determine the binding energy (in eV) of a metal if the kinetic energy possessed by an ejected electron (using one of the photons with wavelength 460 nm) is 2.58 ×10−19 J. .............. eV |
In: Chemistry
discuss at least 2 best practices in pharmaceutical distribution. Illustrate why by providing examples, these are considered best practices. Discuss the ramifications of violation of the best practices you chose. Tie the best practices to cGMP practice. Do you feel that best practice mirrors or expands upon cGMP? How is that the case, and why do you feel this is so. Please discuss what you learned from this article. Your essay should be a minimum of 250 words, with sources cited.
In: Chemistry
A chemistry graduate student is given 250.mL of a 0.10M chlorous acid HClO2 solution. Chlorous acid is a weak acid with Ka=1.1x10^−2.
What mass of NaClO2 should the student dissolve in the HClO2 solution to turn it into a buffer with pH =2.40?
You may assume that the volume of the solution doesn't change when the NaClO2 is dissolved in it.
Be sue your answer has a unit symbol, and round it to 2 significant digits.
In: Chemistry
List three changes you would expect in the IR spectrum of 2,3-dibromocinnamic acid as compared to the IR spectrum of trans-cinnamic acid. Make sure to reference the approximate wavenumber of any relevant peaks and whether they correspond to a stretch or a bend.
In: Chemistry