During a freezing point depression study, two experiments were made with 10 grams of lauric acid. The freezing point of the lauric acid averaged 43.4 deg C. EXP 3: 1.0 grams of an unknown substance are added to the solution and a freezing point for the new solution is 41.0 deg C. EXP 4: 0.5 grams of the same unknown are added to the solution, the new freezing point is 41.6 deg C. Calculate molality of EXP 3 and EXP 4. What are the molar masses of EXP 3 and 4? What is the average molar mass of the unknown substance?
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We are doing a lab on Grignard Reactions, i'm just looking to verify the system by which to find this information: Add about 2 mmol Mg powder, recording the mass to the nearest milligram. In this experiment, magnesium will be the limiting reactant because a 5% excess of bromobenzene will be used. Using your mass of Mg, determine the mass of bromobenzene to be used, being sure to calculate a 5% molar excess.
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If there is 10umol of the radioactive isotope 32P (half-life 14 days) at t=0, how much 32P will remain at (a). 7 days (b) 14 days (c) 21 days and (d) 70 days?
I already know the answers, I have the student companion guide to my biochemistry textbook. It does not tell me how to work out the problem though. If anyone could help it would be appreciated!
The answers are (a) 7mmol (b) 5umol (c) 3.5mmol and (d) 0.3umol
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Lecithin (mixture of phospholipids) is used in cooking to stabilize emulsion (dispersion of a liquid as small droplets in another, immiscible liquid). Explain the interactions involved. )
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a. The emperical formula of sulfur chloride SCl. What is the molecular formula of the compounds if the molecular mass is 135 g mol. (recall that one mole of a substance contains 6.02x10^23 molecules of the substance)?
b. how many atoms of sulfur are in one mole of the compound?
c. how many atoms of chlorine are in one mole of the compound?
d. how many molecules comprise one mole of the compound?
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Phosphorus pentachloride decomposes according to the chemical equation PCI5 (g) <---> PCI3 (g) + Cl2(g) Kc= 1.80 at 250°C
A 0.244 mol sample of PCl5(g) is injected into an empty 2.65 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) and PCl3(g) at equilibrium.
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For Enalapril (drug): Indicate expected absorptions in IR above 1500 cm -1
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A direct hydrogen fuel cell uses hydrogen and air (oxygen) to produce electricity, as we showed in class.
If you wanted a voltage of 2.2 V for your fuel cell device (which can be made of multiple cells), what mix of conversion and/or number of cells would you want to use? Remember: the voltage of cells in series adds up. There are a variety of possible answers.
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At a certain temperature, 0.680 mol of SO3 is placed in a 3.50-L container. 2SO3 (g) <---> 2SO2(g) +O2(g) At equilibrium, 0.190 mol of O2 is present. Calculate Kc.
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The depth of the carburized layer after high temperature carburization for 1 hr at 600oC is 2 micrometers in steel. If the same process is done but for 2 hrs at 700 oC the depth of the carburized layer is 6 micrometers. a) What is the activation energy for diffusion of the carbon? b) What is the depth of the carburized layer in micrometers after carburization at 650C for 1 hr?
Please show your work, I am completely lost. Thanks
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A reaction has a rate constant of 1.28×10−4 s−1 at 25 ∘C and 0.233 s−1 at 75 ∘C.
What is the value of the rate constant at 15 ∘C?
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Consider the reaction CO(g)+NH3(g)⇌HCONH2(g), Kc=0.870 If a reaction vessel initially contains only CO and NH3 at concentrations of 1.00 M and 2.00 M, respectively, what will the concentration of HCONH2 be at equilibrium?
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Balance the combustion reaction of chrysene (C18H12) at 298K. C18H12(s)+ O2(g) CO2(g) + H2O(l)
What is the value of ng for the combustion reaction? ng = mol What is Hcomb of chrysene if Ecomb = -8942.6 kJ/mol?
Hcomb = kJ/mol What is the heat of formation of chrysene? See Thermodynamic Properties Hf = kJ/mol
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The data below were collected for an enzyme-catalyzed reaction.
[S] (mM)
0.25
0.50
1.00
2.00
V0 (mM*s-1)
2.00
3.33
5.00
6.67
Determine Vmax and Km for this reaction.
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A 29-L sample of an ideal gas with γ=1.67 is at 250 K and 50 kPa . The gas is compressed adiabatically until its pressure triples, then cooled at constant volume back to 250 K, and finally allowed to expand isothermally to its original state.
How much work is done on the gas?
What is the minimum volume reached?
In: Chemistry