A 110.1 gram sample of an unknown substance (MM = 189.50 g/mol) is cooled from 233.0 °C to 147.6 °C. (heat capacity of liquid = 1.62 J/g･°C; heat capacity of gas = 1.04 J/g･°C; ∆Hvap = 78.11 kJ/mol; Tb = 160.3 °C)
A. How much energy (in kJ) is absorbed/released to cool the gas?
B. How much energy (in kJ) is absorbed/released to condense the gas?
C. How much energy (in kJ) is absorbed/released to cool the liquid?
D. What is the total amount of energy that must be absorbed/released for the entire process?
In: Chemistry
Design a buffer that has a pH of 8.25 using one
of the weak base/conjugate acid systems shown below.
| Weak Base | Kb | Conjugate Acid | Ka | pKa |
|---|---|---|---|---|
|
CH3NH2 |
4.2×10-4 |
CH3NH3+ |
2.4×10-11 |
10.62 |
|
C6H15O3N |
5.9×10-7 |
C6H15O3NH+ |
1.7×10-8 |
7.77 |
|
C5H5N |
1.5×10-9 |
C5H5NH+ |
6.7×10-6 |
5.17 |
How many grams of the chloride salt of the
conjugate acid must be combined with how many grams of the weak
base, to produce 1.00 L of a buffer that is
1.00 M in the weak base?
grams chloride salt of conjugate acid =
grams weak base =
In: Chemistry
15.) The gallbladder is an intriguing if often overlooked organ that stores bile for the liver in a variety of vertebrates. A biochemically interesting aspect of the gallbladder is that it is one of the few places in the body that regularly has a basic pH. To study enzymatic processes that occur there, appropriate pH conditions must be replicated. The complicating aspect is that the pH is not uniform throughout the entirety of the gallbladder system, where it can range from pH 7.6 to pH 8.5. Conveniently, the buffer range of the H(Tris)+/Tris conjugate pair overlaps well with this system, having a pKa of 8.02. This pKa is convenient to many biological systems, hence its use as a buffer for many experiments.a)What is the full buffer range of the H(Tris)+/Tris system?b)Describe the preparation of two Tris buffer solutions, one for the high end and one for the low end of the gallbladder pH. Make both buffers to a total buffer concentration of 0.110 M with a volume of 1 liter.
In: Chemistry
In: Chemistry
At a certain temperature, the equilibrium constant for the following chemical equation is 4.00.
At this temperature, calculate the molarity (M) of NO2(g) that must be added to a starting concentration of 2.73 M SO2(g) (with no products initially present) in order to have formed 1.30 M SO3(g) and 1.30 M NO(g) when equilibrium is reached.
SO2(g)+NO2(g)−⇀↽−SO3(g)+NO(g)
molarity =
In: Chemistry
Consider the reaction:
8H2S(g)+4O2(g)?8H2O(g)+S8(g)
?[H2S]/?t = -0.047M/s .
Find ?[O2]/?t
Express your answer to two significant figures and include the appropriate units
Find ?[H2O]/?t
Express your answer to two significant figures and include the appropriate units.
Find ?[S8]/?t
Express your answer to two significant figures and include the appropriate units.
Find the rate of the reaction.
Express your answer to two significant figures and include the appropriate units.
In: Chemistry
In: Chemistry
A certain liquid has a vapor pressure of 92.0 Torr at 23.0 ∘ C and 390.0 Torr at 45.0 ∘ C. Calculate the value of Δ H ∘ vap for this liquid.
Calculate the normal boiling point of this liquid.
In: Chemistry
In: Chemistry
if a 4.000gram sample potassium acid phthalate is equivalent to 48.37 ml of a sodium hydroxide solution, what is the concentration of the latter?
In: Chemistry
Consider each of the following reactions and decide whether the standard entropy change for the reaction will be large & positive; or small; or large & negative. 1. large&negative 2. large&positive 3.small
|
a) H2(g) + Cl2(g) = 2 HCl(g) |
|
b) 2 Na(l) + H2(g) = 2 NaH(s) |
|
c) 2 H2O(l) = 2 H2(g) + O2(g) |
|
d) C(s) + H2O(g) = CO(g) + H2(g) |
|
e) Cu(s) + 2 H2SO4(aq) = CuSO4(aq) + 2 H2O(l) + SO2(g) |
f) BaSO4(s) + 2 H2O(g) = BaSO4.2H2O(s)
2. Identify the true statement(s) regarding the entropy of chemical substances.
|
All pure substances have a positive entropy at room temperature. |
|
|
The dissolution of an ionic salt in water usually leads to an increase in entropy of the system (salt + water). |
|
|
So(one mole O3(g)) > So(one mole O2(g)) at 25oC. |
|
|
The entropy of ice at 0oC is lower than that of water at 0oC. |
|
|
When a metallic crystal is heated, its entropy increases due to increasing atomic vibrations. |
In: Chemistry
Calculate the number of moles of ammonia needed to dissolve 0.0010 mole of silver chloride in 4000 mL of solution at 25 degrees Celsius. Ksp for AgCl is 1.8 x 10-10 and the dissociation constant for [Ag(NH3)2]+ is 6.3 x 10-8
In: Chemistry
550.0 gallons of 15.0 M nitric acid were added to a lake. The initial pH of the lake was 5.70 and the final pH was 4.50 . If none of the acid was consumed in chemical reactions, determine the volume of the lake.
In: Chemistry
Chemical analysis of an unknown compound gives a molar mass of
334 g/mol and a percentage composition of 75.42% carbon, 6.63% hydrogen,
8.38% nitrogen, and the rest is oxygen. Calculate the empirical and molecular
formulas for the unknown compound.
2.) Write a balanced chemical equation for the complete combustion of
pentane (C5H12). If 100.00 g of pentane are combusted in excess O2, what mass
of CO2 would be released to the atmosphere?
In: Chemistry
Calculate the percent by mass of the element listed first in the formulas for each of the following compounds. , 1-octanol C8H18O, calcium phosphate Ca3(PO4)2, 3-phenylphenol C12H10O, aluminum acetate Al(C2H3O2)3,
In: Chemistry