In paper chromotography, what form are the metals ( Zn2+, Co2+, Cu2+, Cd2+ , Fe3+, and Ni2+) ions likely to exist in the moving phase (water/hydrochloric acid/acetone) and what groups in the structure of the stationary phase (cellulose) are interacting with the moving ions in solution?
Note: Filter paper (Whatman #1) serves as the stationary phase, and the mobile phase consists of a mixture of acetone and 6 M hydrochloric acid. A single spot of the mixture to be analyzed is applied near one edge of a sheet of filter paper. A spot of solution containing each of the cations that might be in the unknown mixture is also placed near the edge of the same sheet for comparison. The treated strip is then placed in a covered jar or beaker (which acts as a developing chamber) containing a shallow layer of the solvent mixture (see Figure 3). Since filter paper is very permeable to the solvent, the solvent begins to rise up the strip by capillary action. The various spots on the developed chromatogram will be highlighted by treatment with several chemical reagents to enhance their color. The reagents to be used are ammonia, dimethylglyoxime (DMG), and 8–hydroxyquinoline (oxine).
In: Chemistry
Calculate the percent ionization of formic acid (HCO2H) in a solution that is 0.139 M in formic acid. The Ka of formic acid is 1.77
In: Chemistry
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Dissociation Constant For the dissociation reaction of a weak acid in water,HA(aq)+H2O(l)?H3O+(aq)+A?(aq) the equilibrium constant is the acid-dissociation constant, Ka, and takes the formKa=[H3O+][A?][HA] Weak bases accept a proton from water to give the conjugate acid and OH? ions:B(aq)+H2O(l)?BH+(aq)+OH?(aq) The equilibrium constant Kb is called the base-dissociation constant and can be found by the formulaKb=[BH+][OH?][B] When solving equilibrium-based expression, it is often helpful to keep track of changing concentrations is through what is often called an I.C.E table, where I. stands for Initial Concentration, C. stands for Change, and E. stands for Equilibrium Concentration. To create such a table, write the reaction across the top creating the columns, and the rows I.C.E on the left-hand side. Initial (M)Change (M)Equilibrium (M)A+ B?AB |
Part A Aspirin (acetylsalicylic acid, C9H8O4) is a weak monoprotic acid. To determine its acid-dissociation constant, a student dissolved 2.00 g of aspirin in 0.600 L of water and measured the pH. What was the Ka value calculated by the student if the pH of the solution was 2.62? Express your answer numerically using two significant figures.
SubmitHintsMy AnswersGive UpReview Part Part B A 0.100 M solution of ethylamine (C2H5NH2) has a pH of 11.87. Calculate the Kb for ethylamine. Express your answer numerically using two significant figures.
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In: Chemistry
In: Chemistry
Write the equilibrium equations, identify the equilibrium variables such as x +/- y, and calculate the pH of a 0.600 liter solution made up as 1.14 M diprotic base B(aq). Kb1=6.87x10^-6; Kb2=7.15x10^-8
In: Chemistry
Under what circumstances can ?G be negative if ?G'
In: Chemistry
Hey yall, Im working on a quiz I completed. I really need to get
a 100 I worked all the problems out and i was wondering if one of
yall would mind checking it for me. If i missed one if yall could
tell me how to get the correct answer?
1.The intermolecular forces present in CH3NH2 include which of the
following?
I. dipole-dipole
II. ion-dipole
III. dispersion
IV. hydrogen bonding
ANS: I, III, and IV
2. A liquid boils when its
ANS: vapor pressure is equal to, or greater than, the
external pressure pushing on it.
- I was actually torn between picking this answer choice and "vapor
pressure is exactly one atm"...is that wrong?
3. How much energy (heat) is required to convert 52.0 g of ice at
–10.0°C to steam at 100°C?
| specific heat of ice: | 2.09 J/g·°C | ΔHfus = 6.02 kJ/mol |
| specific heat of water: | 4.18 J/g·°C | ΔHvap = 40.7 kJ/mol |
| specific heat of steam: | 1.84 J/g·°C |
ANS:157.8
kJ
4. Which of the following
liquids would have the highest viscosity at 25°C?
| CH3Br |
| C2H5OH |
| CH2Cl2 |
| ANS : HOCH2CH2OH |
| CH3OCH3 |
5. Which of the following would be
expected to have the lowest vapor
pressure at room temperature?
| ANS: water, bp = 100°C |
| acetone, bp = 56°C |
| ethanol, bp = 78°C |
| methanol, bp = 65°C |
6. Given the following liquids and
their boiling points, which has the highest vapor pressure at its normal boiling
point?
| ANS: | The vapor pressure of each of the liquids at its normal boiling point would be the same. |
| ethanol, bp = 78°C |
| benzene, bp = 80°C |
| water, bp = 100°C |
|
methanol, bp = 65°C |
7. Which of the following liquids
would make a good solvent for iodine, I2?
| ANS: CS2 |
| CH3OH |
| HCl |
| H2O |
| NH3 |
8. What is the boiling point of a
solution of 11.0 g of lactose (C12H22O11) in 145.0g of water? (Kb
(H2O) = 0.52 °C/m)
ANS: 100.1 deg C
9. Calculate the molality of a 20.0% by mass
ammonium sulfate (NH4)2SO4 solution. The density of the solution is
1.117 g/mL.
ANS: 1.89
10. A solution that is 33.6 % by mass of phenol (C6H5OH) in water
is prepared. What is the mole fraction of the phenol?
ANS: 0.0883
In: Chemistry
Part A
Consider the reaction
2H3PO4→P2O5+3H2O
Using the information in the following table, calculate the average rate of formation of P2O5 between 10.0 and 40.0 s.
| Time (s) | 0 | 10.0 | 20.0 | 30.0 | 40.0 | 50.0 |
| [P2O5] (M) | 0 | 3.00×10−3 | 6.00×10−3 | 7.80×10−3 | 9.00×10−3 | 9.60×10−3 |
Express your answer numerically in molar per second.
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| Rate of formation of P2O5 = | M/s |
SubmitHintsMy AnswersGive UpReview Part
Part B
This question will be shown after you complete previous question(s).
Part C
Consider the reaction
5Br−(aq)+BrO−3(aq)+6H+(aq)→3Br2(aq)+3H2O(l)
The average rate of consumption of Br− is 1.35×10−4M/s over the first two minutes. What is the average rate of formation of Br2 during the same time interval?
Express your answer numerically in molar per second to three significant figures.
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| Rate of formation of Br2 = | M/s |
Part D
This question will be shown after you complete previous question(s).
In: Chemistry
1)Boron trichloride is prepared from the following reaction. 2B2O3 + 6Cl2 + 3C --> 4BCl3 + 3CO2 If 8.254g of B2O3 is mixed with 4.446g of Cl2 and 4.115g of C then answer the following questions.
A) What is the theoretical yield of boron trichloride in grams?
B)How much of each of the excess reagents with remain once the reaction is complete? (report in grams)
2)If the yield of the reaction in question 2 is known to be only 73.42%, how much of each of the three reagents would you need to obtain 10.000g of boron trichloride?
In: Chemistry
A galvanic cell is constructed with a silver-silver chloride electrode, and a nickel strip immersed in a beaker containing 3.01 x 10-2 M solution of NiCl2. Determine the balanced cell reaction and calculate the potential of the cell. Enter in volts. (assume a temperature of 25
In: Chemistry
Given that the following reaction begins at equilibrium, which
of the following describes the reaction immediately after a small
portion of
CO2(g)
is removed from the reaction container?
CO(g) +
H2O(g)
<---->
CO2(g)
+ H2(g)
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Q < Kc, reaction is spontaneous in reverse direction |
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Q < Kc, reaction is spontaneous in forward direction |
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Q > Kc, reaction is spontaneous in reverse direction |
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Q > Kc, reaction is spontaneous in forward direction |
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No effect 2. Use the initial concentration and initial rate data in the table
to determine the rate law for the reaction:
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In: Chemistry
the reaction of 7.26 g of carbon with excess O2 yeilds 8.20 g of CO2. What is the percent yeild of the reaction?
In: Chemistry
Both solid LiH and CaH2 react with water to produce hydrogen gas and the corresponding hydroxide, LiOH or Ca(OH)2. A 0.850g sample of a mixture of LiH an CaH2 produces 1.200 liters of H2 at STP. What percentage of the starting mixture was LiH? (Give both mole percent and percent by weight)
In: Chemistry
How are the ?H values for reactions determined in the first place? The reactions are run in a calorimeter, which restricts and defines the surroundings so that thermal energy transfer to or from the surroundings (prompted by a change in temperature ?T) can be easily measured. Why measure the thermal energy change of the surroundings? So that we can then determine the thermal energy change of the system. Remember that thermal energy change, or heat transfer q , of the system and surroundings can be expressed as:
qsystem + qsurroundings = 0 (energy neither created nor destroyed)
qsystem = ? qsurroundings
One other thing: if your system is a tangible thing with a specific heat capacity, and your surroundings are tangible with a specific heat capacity, you can use the following:
qsystem = (m s ?T)system and qsurroundings = (m s ?T)surroundings
Substitute this into qsystem = ? qsurroundings to get:
(m s ?T)system = ?(m s ?T)surroundings
What mass of a hot (85.0
In: Chemistry
Use the following for all problems involving water: Cice = 2.09 J/gºC Cwater = 4.184 J/gºC Csteam = 2.03 J/gºC ΔHfus = 6.01 kJ/mol ΔHvap = 40.7 kJ/mol Question 1 (1 point) How many grams of ice at 0ºC can be melted by 7.70 kJ of heat? grams (3 SF) Blank 1: Question 2 (1 point) How many kilojoules of heat are required to completely melt a 10.0 gram popsicle at 0ºC and raise the temperature to 22ºC? Assume the same properties as water. kJ (4 SF) Blank 1: Question 3 (1 point) 32.0 grams of ice at -28.0ºC melts into water at a temperature of 19.0ºC. How much energy is required to increase the temperature from -28.0ºC to 0ºC? J (3 SF) How much energy is required to melt the ice? kJ (3 SF) How much energy is required to increase the temperature from 0ºC to 19.0ºC? J (3 SF) What is the total energy required? KILOJOULES Blank 1: Blank 2: Blank 3: Blank 4: Question 4 (1 point) How much energy is required to raise the temperature of 18.0 grams of water at 27.7ºC to steam at 130ºC? KILOJOULES (3 SF) Blank 1: Question 5 (1 point) How much energy is required to raise the temperature of 1.99 grams of ice from -28.4ºC to steam at 111.2ºC? KILOJOULES Blank 1: Question 6 (1 point) How much energy is given off when 10.0 grams of oxygen gas is cooled from 25ºC to -232ºC? (Hint: Draw a heating curve for oxygen) KILOJOULES (3 SF) MP of O2 = -219ºC BP of O2 = -183ºC ΔHvap = 6.82 kJ/mol ΔHfus = 0.443 kJ/mol Cgas = 0.954 J/gºC Cliquid = 1.464 J/gºC Csolid = 3.256 J/gºC Blank 1:
In: Chemistry