What is the pH at the equivalence point of the titration of 0.150 L of 0.500 M formic acid with 30.0 mL of 2.50 M sodium hydroxide. Ka = 1.8 X10^-4
In: Chemistry
Consider the following reaction :
Fe3+ (aq) + SCN- (aq) ---> Fe(SCN)2+ (aq)
Starting with 4.00 mL of .200 M Fe3+ (aq) in a cuvette, 0.10 mL increments of 0.00100 M SCN- (aq) will be added. Assume that because [Fe3+ (aq)] >> [SCN- (aq)], the [Fe(SCN)2+] concentration can be calculated from the limiting reagent, SCN-. Calculate [Fe(SCN)2+].
| Volume .00100 M KSCN mL | [Fe(SCN)2+] (M) |
| .10 | |
| .20 | |
| .30 | |
| .40 | |
| .50 | |
| .60 | |
| .70 | |
| .80 | |
| .90 | |
| 1.00 |
In: Chemistry
11-Which of the following does NOT regulate biochemical reactions?
A. Regulation of enzyme amounts.
B. Regulation of access of substrates to certain compartments.
C. Alteration of Go' by raising or lowering reactant concentrations
. D. Regulation of the catalytic activities of enzymes.
E. Alteration of the amounts of allosteric modifiers (regulator molecules).
In: Chemistry
Which of the following experimental methods cannot be used to measure the rate of a reaction?
a. measurement of the change in the partial pressure of a gas-phase reactant over time
b. measurement of the equilibrium concentration of an acidic product via titration with a strong base
c. measurement of the absorbance of a colored reactant with time
d. measurement of the absorbance of a colored product with time
e. measurement of the change in the partial pressure of a gas-phase product over time
f. none of the above can be used to measure the rate of the reaction
g. I don't know
In: Chemistry
what are ∆U, ∆H, ∆G, ∆A, ∆S, ∆Ssur, q and w for the following changes involving a perfect diatomic gas – if all changes are reversible –
(a) isentropic change
(b) isochoric change
(c) isobaric change
(d) isothermal change
(e) isenthalpic change
(entropy S, enthalpy H, Gibbs energy G and Helmholtz energy A)
Note, the perfect gas equation of state is pV = nRT.
In: Chemistry
1.) Principal Quantum Number
What values can this number have? What information does it provide in relation to an electron? (Be complete in your answer.)
In: Chemistry
Ag+ is complexed by the chelating ligand trien (triethylenetetramine, NH2(CH2)2NH(CH2)2NH(CH2)2NH2).
| Ag+ + trien ⇌ Ag(trien)+ | Kf = 5.0×107 |
40.8 mL of 0.0273-M trien solution is added to 25.0 mL of
0.0146-M silver nitrate solution.
What is [Ag+] at equilibrium?
In: Chemistry
"Low concentrations of dioxin near the detection limit gave the following dimensionless instrument readings: 193.3, 156.5, 150.3, 162.3, 207.3, 148.1, 211.1, 189.7, 122.7, and 193.5. Ten blanks had a mean reading of 47.3. The slope of the calibration curve is 2.55 × 10x9 M–1. Estimate the signal and concentration detection limits and the lower limit of quantitation for dioxin."
I know the signal detection limit is yblank + 3s and the concentration limit is 3s/m, but what is ysample to calculate m?
In: Chemistry
Using the Line-Angle structure of morphine, circle or highlight all polar regions of the molecule. Make a reasonable prediction about whether your molecule will be soluble in water or not. Explain your reasoning. If the drug seems to be borderline in molecular polarity, making it difficult to predict solubility, explain your reasoning and the difficulty involved. Compare your predictions with the solubility information on the literature.
In: Chemistry
The following data was generated for an isolated mammalian dihydrofolate reductase.
[7,8-dihydrofolate] (mM) V (mol/s) V (mol/s) with methotrexate
1.1 333 169
2.0 444 265
5.0 667 465
A. Graph the data with and without methotrexate on a Lineweaver-Burk plot. Clearly label which line is which.
B. Calculate Km for the enzyme in the presence and absence of methotrexate. Is this a competitive or non-competitive inhibitor?
C. Considering that deoxynucleotide concentrations are limiting in the cell, what effect will addition of methotrexate have on DNA replication? Explain your reasoning.
In: Chemistry
1.The reaction of aluminum metal (Al) with oxygen (O2) forms Al2O3. Write a balanced equation for this redox reaction. Write two half reactions to show how many electrons are gained or lost by each species.
Redox Reaction:
Oxidation Reaction:
Reduction Reaction:
2. Be sure to answer all parts. Hydrocarbons are compounds that contain only C and H atoms. When a hydrocarbon reacts with O2, CO2 and H2O are formed. Write a balanced equation for the combustion of the following hydrocarbon, a high-octane components of gasoline. Do not include states of matter in your answer. C8H18 (isooctane)
3.One dose of an antacid contains 750. mg each of Mg(OH)2 and Al(OH)3. How many moles of each compound are contained in a single dose? Use proper scientific notaion to report the answers.
---- × 10 mol Mg(OH)2
----× 10 mol Al(OH)
In: Chemistry
1. What answer should be reported, with the correct number of significant figures, for the following calculation? (433.621 - 333.9)
In: Chemistry
1)Suppose the reaction
Ca3(PO4)2 +
3H2SO4 → 3CaSO4 +
2H3PO4 is carried out starting with 149 g of
Ca3(PO4)2
and 91.0 g of H2SO4. How much phosphoric acid
will be produced?
2)For the reaction N2(g) + 2H2(g) → N2H4(l), if the percent yield for this reaction is 60.0%, what is the actual mass of hydrazine (N2H4) produced when 22.00 g of nitrogen reacts with 5.25 g of hydrogen?
In: Chemistry
A buffer is prepared by adding 300.0 mL of 0.050 M Ch3COONa to a 500.0 mL of 0.100 M CH3COOH. What is the pH of this buffer? Ka=1.8x10^-5
What is the pH of the buffer upon the addition of 10.0 mL of a 1.2x10^-3 M HCl solution?
In: Chemistry
For a particular redox reaction MnO2 is oxidized to MnO4– and Cu2 is reduced to Cu . Complete and balance the equation for this reaction in basic solution. Phases are optional.
This is what I keep getting: http://tinypic.com/r/sq1hc3/9
In: Chemistry