4. How do you decide whether to use enough hot water to dissolve acetanilide or enough to dissolve phenacetin?
5. If someone mixed sand into your unknown sample so you could not separate the grains of sand from the unknown solid, how could you separate them? Would the same action work if sucrose was mixed into your unknown?
6. Why would you allow the filtered liquid to cool slowly? What would happen if you did not allow slow cooling?
7. Why and when would you put the recrystallizing solution in an ice bath?
In: Chemistry
A 25.0 mL sample of 0.100 HClO4 is titrated with a 0.100 M NaOH solution. What is the pH after the addition of 10.0 mL of NaOH? (HClO4 is a strong acid)
In: Chemistry
200.0 mL of 1.5 x 10^-3 M Cu(NO3)2 is
mixed with 250.0 mL of 0.20 M NH3. The overall formation constant
for the formation of the [Cu(NH3)4]2+ complex
is 1.7·1013. (8 points)
a) What is the [Cu2+] at equilibrium?
b) Does CuS precipitate with a concentrated H2S out of this
solution at pH=6? The Ksp for CuS is 8·10-37.
In: Chemistry
Give examples from the literature of metal complexes with coordination numbers (CN) of 2, 3, 4, 5, 6, 7 and 8 (formula, structure). What is the highest Coordination Number found for a metal ion?
In: Chemistry
Given the following data:
3FeO(s) + CO2(g) → Fe3O4(s) + CO(g) ΔH° = -18.0 kJ
FeO(s) + CO(g) → Fe(s) + CO2(g) ΔH° = -11.0 kJ
Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g) ΔH° = -23.0 kJ
Calculate ΔH° for the reaction: 3Fe2O3(s) + CO(g) → 2Fe3O4(s) + CO2(g)
In: Chemistry
What would be the effect of each of the following sources of error in the reaction between Mg and HCl? Would they result in a high, low, or unaffected value for the heat of reaction? Why?
A. The calorimeter absorbs heat.
B. The thermometer reads 2 °C low at all temperatures.
C. The actual molarity of the HCl is slightly higher than reported
on the bottle.
D. The mass of the filter paper was not subtracted in the determination of ∆H1.
In: Chemistry
What is the osmotic pressure, in torr, of a 3.00% solution of
NaCl in water when the temperature of the solution is 45 ºC? Enter
your answer scientific notation.
In: Chemistry
Recalculate the percent dissociation of 0.19M HN3 in the presence of 0.19M HCl.
In: Chemistry
A 150.0 mL gas tank contains 51.2 g of oxygen gas and 32.6 g helium gas. What is the total pressure in the tank? What is the partial pressure of oxygen?
In: Chemistry
Which statement about the following redox reaction in acidic
solution is not correct?
MnO4??(aq) +
I???(aq) ? MnO2(s) +
I2(aq)
| A) H2O and H?+ can be used to balance the oxygen atoms, if necessary, in each of the half-reactions. | |
| B) MnO4??(aq) ? MnO2(s) is the reduction step. | |
| C) I???(aq) ? I2(aq) is the oxidation step. | |
| D) The redox atoms are already balanced in this reaction. |
In: Chemistry
The energy from condensing water vapor is used to melt ice at 0oC. What mass (kg) of ice can be melted by condensing 0.500 kg of water vapor? (ΔHfus = 6.01 kJ/mol and ΔHvap = 40.7 kJ/mol)
In: Chemistry
) The standard enthalpies of formation of SO2 and SO3 are ?297 and ?396 kJ/mol respectively. Calculate the standard enthalpy of reaction for the reaction: SO2(g) + 1/2O2(g)??SO3 (g)
In: Chemistry
Choose 3 journal articles you think will be useful as references for your formal lab report paper. You may use review articles or research articles. You might try typing in a keyword for your topic and the word “review”. Obtain copies either from the library or from an on-line resource. In the space provided below, explain in no more than 5 sentences per article why you feel the article you have selected is appropriate for your paper. Just because your key word appears in the title does not automatically mean the paper will be useful for your report. Briefly state how you will use it in your report. Attach a copy of each article to the assignment before handing it in. Directions on how to access electronic journals through the University of Houston Library are at the end of this document. If you cannot download an article you desire directly from the PubMed website, try through the University of Houston Library electronic journals collection. If the university does not have the electronic version on file, you will have to go to the library and copy it on a copy machine (the old-fashioned way). If you cannot obtain a copy of the article, you can place a request through interlibrary loan at the service desk at the library or you will need to find another article.
in Crystallography
you can chose any subject you want :)
In: Chemistry
At 700 K acetaldehyde decomposes in the gas phase to methane and
carbon monoxide. The reaction
isCH3CHO(g)?CH4(g)+CO(g)
A sample of CH3CHO is heated to 700 K and the pressure is measured
as 0.20 atm before any reaction takes place. The kinetics of the
reaction are then followed by measurements of total pressure and
these data are obtained:
| t(s) | 0 | 1000 | 3000 | 7000 |
| PTotal (atm) | 0.20 | 0.22 | 0.24 | 0.28 |
Rate law --> Rate=??PCH3CHO?t=4.510?4atm?1?s?1PCH3CHO2
Find total pressure after 1.17104s
In: Chemistry
An unknown pollutant gas has contaminated one of your samples of Ne(g). You test your Ne sample, at constant T and P and find that it effuses through a balloon 3.87 times more rapidly than a pollutant. What is the molar mass of the pollutant gas?
In: Chemistry