When a 0.860 g sample of an organic compound containing C, H, and O was burned completely in oxygen, 1.64 g of CO2 and 1.01 g of H2O were produced. What is the empirical formula of the compound?
In: Chemistry
For each of the following pairs of aqueous solutions (all are at 300 K, unless otherwise stated), circle the one that has a higher concentration of solute:
1. 1.75 M NaCl or 1.75 m NaCl
2. 1.0% by mass KI or 1.0% by mass KBr
3. a saturated solution of n-butanol (CH3(CH2)2(CH2OH) or a saturated solution of n-decanol (CH3(CH2)8CH2OH)
4. a saturated solution of O2 at 298 K or a saturated solution of O2 at 358 K
5. a saturated solution of He under 1 atm of He or a saturated solution of Xe under 1 atm of Xe
**It would be very very helpful if you can provide an explanation for each one**
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A volume of 84 mL of 0.060 M NaF is mixed with 28 mL of .15 M Sr(NO3)2. Calculate the concentrations of the following ions in the final solution (Ksp for SrF2 is 2.0x10^-10)
In: Chemistry
2C2H2(g) + 5O2(g) ---> 4CO2(g) + 2H2O(l)
A. Write the standard enthalpy of formation equations for those that apply:
B. Manipulate these equations and calculate the enthalpy of reaction:
C. Use the enthalpy of reaction equation and the enthalpy of formations to check your work for (B)
In: Chemistry
#1. Estimate ΔH for the reaction using bond dissociation energies. Give your answer in kcal. C6H12O6 has five C−C bonds, seven C−H bonds, seven C−O bonds, and five O−H bonds.
#2. Is the reaction exothermic or endothermic?
#3. The following equation shows the conversion of aluminum
oxide (from the ore bauxite) to aluminum:
2Al2O3(s)→4Al(s)+3O2(g),
ΔH = +801.0 kcal
----> a. Is the reaction exothermic or endothermic?
In: Chemistry
Consider the titration of a weak base (B- ) with a strong acid (HCl). Draw (this can be hand drawn) a pH (not pOH) vs mL HCl graph (it will not look the same as the one in question #13; if you start with a weak base, will the pH be low or high? As H+ is added, will the pH increase or decrease?). Label the titration curve with letters A-E, and describe the relative quantities of the dissociated base (B- ) and its conjugate acid (HB), H+ and OHat each point throughout the titration (before the ½ equivalence point [A], at the ½ equivalence point [B], after the ½ equivalence point but before the equivalence point [C], at the equivalence point [D], and after the equivalence point [E]). Locate the position where pH = pKb on your graph.
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A layer of peat beneath the glacial sediments of the last ice age had a carbon-14 content of 25 % of that found in living organisms. How long ago was this ice age?
Express your answer using four significant figures
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Constant boiling HCl has a concentration of 11.6 M. Your laboratory assistant is going to dilute this acid for you to create a stock solution of HCl for you to use in this experiment. What volume of the 11.6 M HCl must the assistant add to one liter volumetric flask so that the concentration of the stock solution will be 0.62 M after dilution to the mark the water?
What is the pH of this stock solution?
You will now use this 0.62 M HCl solution to carry out a series of dilutions, measuring the pH of each diluted sample. Calculate the [Cl-] and [H+] concentrations and the pH of each sample.
Sample A will be produced bby pipetting 1.00 mL of the stock solution into a 25 mL volumetric, and diluting to the volume with distilled water.
[Cl-]=
[H+]=
pH=
Sample B will be produced by pipetting 1.00 mL of sample A into a 25 mL volumetric, and diluting to volume with distilled water.
[Cl-]=
[H+]=
pH=
Sample C will be produced by pipetting 1.00 mL of sample B into a 25 mL volumetric, and diluting to volume with distilled water.
[Cl-]=
[H+]=
pH=
Sample D will be produced by pipetting 1.00 mL of sample C into a 25 mL volumetric, and diluting to volume with distilled water
[Cl-]=
[H+]=
pH=
Sample E will be produced by pipetting 1.00 mL of sample D into a 25 mL volumetric, and diluting to volume with distilled water
[Cl-]=
[H+]=
pH=
Sample F will be produced by pipetting 1.00 mL of sample E into a 25 mL volumetric, and diluting to volume with distilled water
[Cl-]=
[H+]=
pH=
In: Chemistry
Different manufacturers claim to have the best antacid. Which of the following tablets would neutralize the most acid for the money?
A. Rolaids (550 mg CaCO3 and 110 mg Mg(OH)2 per tablet) – 150 tablets for $9.44
B. Tums (500 mg CaCO3 per tablet) – 150 tablets for $5.49
C. Phillips (1200 mg Mg(OH)2 per 15 mL) – 769 mL for $9.99
Show all work to get full credit and circle your final answer. You may need to write balanced chemical equations…
In: Chemistry
What are the three basic types of solids and the composite units of each? What types of forces hold each type of solid together?
In: Chemistry
Air. Write in reasonable detail, using the macroscopic nature (our experience) and microscopic nature (molecular level) the composition of air, pollutants in air, where pollutants come from, how they impact health and environment, and what steps are being taken to keep air clean. Share your thoughts on this topic.
In: Chemistry
At 25 C, you conduct a titration of 15.00 mL of a 0.0400 M AgNO3 solution with a 0.0200 M NaI solution within the following cell:
Saturated Calomel Electrode || Titration Solution | Ag (s)
For the cell as written, what is the voltage after the addition of the following volume of NaI solution? The reduction potential for the saturated calomel electrode is E = 0.241 V. The standard reduction potential for the reaction
Ag+ + e- --> Ag(s)
is E0 = 0.79993 V. The solubility constant of AgI is Ksp = 8.3 x 10^-17.
.600 mL = ______ V
10.30 mL= ______ V
30.00 mL= ______V
38.80 mL= ______V
In: Chemistry
i keep getting 1 wrong.. its says the total V is hcl and water added together but i did it and its not right. thanks
1. You add Hydrochloric Acid to distilled water. If
all the HCl dissociates in solution, calculate the pH of the final
solution given the following data. (assume the liquid volumes are
addative)
Volume of distilled water used 27.81 mL
Volume of HCl added 1.44 mL
Concentration of added HCl 1.848 M
pH of diluted HCl solution ___________________
2. You weigh a sample of a monoprotic unknown acid and
dissolve it in 50.00 mL of distilled water. Exactly half of this
solution is titrated with Sodium Hydroxide to the phenolphthalein
end point.
The pH of the other half of the original solution is measured with
a pH meter. The "neutralized" solution is added to the "original"
solution and the pH of this combined "final" solution is also
measured.
The following are the measured values:
Mass of unknown acid 1.8105 g
Volume of NaOH used in titration 13.80 mL
Concentration of the NaOH used 0.2213 M
pH of the original acid solution 2.13
pH of the final acid solution 3.24
CALCULATE the following
(a) Molecular Weight of Acid used in titration
___________________
(b) Molarity of UNKNOWN Acid solution from titration
___________________
(c) Ka of UNKNOWN Acid ___________________
(d) Concentration of undissociated Acid from pH measurements
___________________
(e) Total concentration of UNKNOWN acid from pH measurements
___________________
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Why can Hydrogen and helium only hold two electrons in there valence shell, but Neon can hold 8?(You will receive extra credit if you can explain this with quantum numbers)
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What is the half-life (T1/2) of a radioactive element with the following conditions?
-Initial Activity = 1000 milliCuries
-Final Activity = 400 milliCuries
-Elapsed Time= 20.0 days
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