In: Chemistry
A TLC plate showed two spots of Rf 0.25 and 0.26. The plate was dried carefully, and returned to the developing chamber. What would you expect to see after the second development was complete?
In: Chemistry
| Reduction half-reaction | E∘ (V) |
| Ag+(aq)+e−→Ag(s) | 0.80 |
| Cu2+(aq)+2e−→Cu(s) | 0.34 |
| Sn4+(aq)+4e−→Sn(s) | 0.15 |
| 2H+(aq)+2e−→H2(g) | 0 |
| Ni2+(aq)+2e−→Ni(s) | −0.26 |
| Fe2+(aq)+2e−→Fe(s) | −0.45 |
| Zn2+(aq)+2e−→Zn(s) | −0.76 |
| Al3+(aq)+3e−→Al(s) | −1.66 |
| Mg2+(aq)+2e−→Mg(s) | −2.37 |
1)
Use the table of standard reduction potentials given above to calculate the equilibrium constant at standard temperature (25 ∘C) for the following reaction: Fe(s)+Ni2+(aq)→Fe2+(aq)+Ni(s)
2)
Calculate the standard cell potential (E∘) for the reaction
X(s)+Y+(aq)→X+(aq)+Y(s)
if K = 3.80×10−4.
Express your answer to three significant figures and include the appropriate units.
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Consider the following liquid junction cell at room temperature:
Zn(s) / ZnSO4(aq) // CuSO4(aq) / Cu(s)
The left side of the cell contains an electrolyte solution at 9.26*10^-2 M and the right side of the cell contains an electrolyte solution at 7.32*10^-2 M.
Calculate the observed cell potential using the Nernst Equation, the Debye-Huckel Limiting Law, and ionic activities.
In: Chemistry
1. a. What is the pH of a solution formed by combining 50.00 mL of a 0.0855 M acetic acid solution, 25.00 mL of 0.1061 M NaOH solution and 25.00 mL of deionized water? Show your work.
b. What is the pH when the solution in 1a is diluted 1 mL in 10 mL total volume? Show your work.
c. What is the pH when 25.00 mL of the solution in #1a has 5.00 mL of a 0.1056 M HCl solution added to it? Show your work.
c. What is the pH when 25.00 mL of the solution in #1a has 5.00 mL of a 0.1056 M NaOH solution added to it? Show your work.
In: Chemistry
A 500 mL saturated solution of MgCO3 (MM =
84.3 g/mol) is reduced to 120 mL by evaporation. What mass of solid
MgCO3 is formed? Ksp = 4.0 x 10-5
for MgCO3.
EDIT: If ions can evaporate in water then the answer below is
right. If not, this is how I solved the problem.
MgCO3 dissolves at a 1:1 ratio, therefore
Ksp=s2 and s=Ksp1/2 (or
sqrt of Ksp)
s = (4.0x10-5)1/2 = .00632 M
Using the equation M1V1=M2V2
M1 = s = 0.00632; V1 = 0.500; V2 = 0.120
Solving for M2 = 0.0263 M
Then multiply M2 by MM to get the mass.
Therefore, mass = (0.0263)(84.3) = 2.22g
Can anyone confirm this?
In: Chemistry
Using ICE tables and acid-base equations, compare the change in pH that occurs when 10 mL of a 0.10 M NaOH is added to 100 mL of pure water, and when it is added to 100 mL of a benzoic acid buffer soltution that is 0.15 M in both C6H5CO2H and C6H5CO2Na. *Hint: M1V1=M2V2
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For analysis of a calcium sample, it is desirable to obtain a precipitate weighingabout 0.50g. What size sample should be taken from a mixture which isapproximately 56% CaO?
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The following are some calculation questions related to the experiment. Please include the questions and their answers in your report:
a) A 0.05 L solution of 0.5 mol/L NaOH was titrated until neutralized into a 0.025 L sample of HCl. What was the concentration of the HCl?
b) 50 L of 2.0 mol/L Hydrochloric acid is titrated with sodium hydroxide to form water and sodium chloride. How many moles of sodium hydroxide are consumed in this reaction?
c) 100 L of 5 mol/L NaOH are required to fully titrate a 50 L solution of HCl. What is the initial concentration of the acid?
In: Chemistry
A) Consider the reaction
2N2(g) +
O2(g) --->
2N2O(g)
Using the standard thermodynamic data in the tables linked above,
calculate deltaGrxn for this reaction at 298.15K if the
pressure of each gas is 35.48 mm Hg.
______ kJ/mol
B) Consider the reaction
CH4(g) + H2O(g)
--->
3H2(g) +
CO(g)
Using the standard thermodynamic data in the tables linked above,
calculate deltaG for this reaction at 298.15K if the pressure of
each gas is 12.05 mm Hg.
______ kJ/mol
C) Consider the reaction
2N2(g) +
O2(g) ----->
2N2O(g)
Use the standard thermodynamic data in the tables linked above.
Calculate deltaG for this reaction at 298.15K if the pressure of
N2O(g) is reduced to
10.45 mm Hg, while the pressures of
N2(g) and
O2(g) remain at 1 atm.
______ kJ/mol
In: Chemistry
The titration process is used to analyze the content of some food product. Let's say you are analyzing the concentration of acetic acid in the vinegar. Answer the following question:
• What would you categorize the vinegar, an acid or a base?
You have 5 mL of vinegar in a flask and 2 drops of phenolphthalein indicator. You titrate exactly 36.9 mL of 0.1 mol/L NaOH from a burette directly into the flask which gives you a pale pink color. This means the solution has reached neutralization.
• Calculate n of the NaOH.
• Calculate c of the vinegar in mol/L.
• Depending on your answer for the previous question complete the following sentence:
one liter of vinegar contains …………………………. mol of acetic acid.
In: Chemistry
In: Chemistry
Draw the molecular orbital diagram for the valence electrons in H2O. Using the electron configuration and the Walsh correlation diagram, explain why H2O is bent and not linear.
In: Chemistry
The chief compound in marble is CaCO3. However, marble is readily attacked by acids.
[Ca2+] in normal rainwater of pH 5.0 = 0.024 M
a) Determine the molar solubility of marble (that is, [Ca2+] in a saturated solution).
b) Determine the equilibrium constant for the overall reaction that occurs when marble reacts with acid
CaCO3 (s) + H3O+ ↔ Ca2+ (aq) + HCO3- (aq) + H2O (l)
My problem is that I have been given no more information other than what is written above. I'm not sure how to go about solving it with this amount of information.
In: Chemistry