A mixture of methane (CH4) and ethane (C2H6) is stored in a container at 294 mm Hg. The gases are burned in air to form CO2 and H2O. If the pressure of CO2 is 346 mm Hg measured at the same temperature and volume as the original mixture, calculate the mole fraction of the gases.
Mole fraction of methane: _____________
Mole fraction of ethane: _________________
In: Chemistry
Write a balanced net ionic equation for the reaction of manganese(II) hydroxide, Mn(OH)2, with hydrochloric acid.
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Mn(OH)2(s) + 2H+(aq) ---> Mn2+(aq) + 2H2O(l) |
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Mn(OH)2(s) + 2H+(aq) ---> MnH2(s) + 2OH−(aq) |
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(OH)3(aq) + 3H+(aq) ---> 3H2O(l) |
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3OH−(aq) + 3H+(aq) ---> 3H2O(l) |
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Mn2+(aq) + 2Cl−(aq) ---> MnCl2(aq) |
In: Chemistry
Question:1
You dissolve 312 mg of a compound
(AwBxCyDz) in water
producing 14.31 mL of solution and use the photometer and standard
solutions to find that the concentration of the A is 1.24 x
10-2 M. The molar mass of A is 114.52 g/mol.
Moles of A in the solution sample:________________________________
Mass of A in the solution sample: _________________________________
Mass % of A in the compound: _______________________________
Moles of A in 100 grams of the compound:
________________________________
Question:2
The compound, AwBxCy, like all
compounds has an oxidation number of 0 (zero). The oxidation number
of A is +1, the oxidation number of B is +2, and the oxidation
number of C is –1. If there are two moles of A for every 3 moles of
C in one mole of the compound, what is the empirical formula of the
compound?
Question:3
Given the compound,
KwAlx(SO4)y(H2O)z.
100.00 grams of the compound contains 8.24 grams of potassium and
5.69 grams of aluminum. What is the formula of the compound?
In: Chemistry
1. Retention time (tR) is a measure of how long a compound is retained on a stationaryphase in column in column chromatography. In TLC, Rf was a measure of how long thecompound was retained on the stationary phase. What is the relationship between tR and Rf?
2. What would be the order of elution if one separated the pigments of spinach on columnchromatography?
3. What if any would you have to change in terms of the mobile phase if you wanted toactually perform the column chromatography in order to separate the pigments of spinachcompare to the one used for the TLC Experiment? Explain.
4. Why is it important to keep the solvent level above the stationary phase? What wouldhappen if one lets the solvent get much lower than the alumina stationary phase?
In: Chemistry
Discuss the relationship between a gas chromatogram and mass spectrometry data. How do they correspond to identify the compounds present?
In: Chemistry
N, N'-Dimethylformamide (DMF) is a commonly-used polar solvent. Its normal boiling point is 426K and is has ΔH°vap = 47.6 kJ/mol. Suppose a laboratory vacuum system is able to maintain a flask at total pressure of 5.0 Torr. Estimate the temperature at which DMF will boil in this flask.
Please show all work.
In: Chemistry
8C How many liters of a 3.14 M K2SO4 solution are needed to provide 81.3 g of K2SO4 (molar mass 174.01 g/mol)? Recall that M is equivalent to mol/L.
Expresss your answer to three significant figures.
7B Gastric acid pH can range from 1 to 4, and most of the acid is
HCl.
For a sample of stomach acid that is 1.26×10−2M in HCl, how many moles of HCl are in 12.1 mL of the stomach acid?
Express the amount to three significant figures and include the appropriate units.
PLEASE, IF YOU CAN, ANSWER ALL OF THEM I WOULD GREATLY APPRECIATE IT!
In: Chemistry
An aqueous solution of formic acid, HCOOH, is prepared at 0.075 M. The acid-ionization constant is Ka = 1.8 x 10-4. Because this is a weak acid, you may presume that the ionic strength is negligible (m = 0). Calculate:
a) the pKa of HCOOH
b) [H+]
c) [HCOO-]
d) [HCOOH] at equilibrium
In: Chemistry
1.00 mol of A and 1.00 mol of B are placed in a 4.00-L container. After equilibrium is established, 0.400 mol of D is present in the container. Calculate the equilibrium constant for the reaction: A(g) + 3 B(g) <---> C(g) + 2 D(g)
In: Chemistry
The hydrolysis of 1-chloro-1-methyl cylcoheptane in 80% ethanol follows a first order rate equation. The values of the specific reaction rate constants are:
| temp/C | 0 | 25 | 35 | 45 |
| k/s-1 | 1.06x10-5 | 3.19x10-4 | 9.86x10-4 | 2.92x10-3 |
1. Plot Ln(k) against 1/T
2. Calculate the activation energy
3. Calculate the pre-exponential factor
In: Chemistry
The next 7 questions are related to the titration of 60.0 mL of a 0.0250 M Zn2+ solution with 0.0600 M EDTA in a solution buffered at pH 11. Assume that the temperature is 25 oC and that the formation constant for Zn2+ is 3.13 x 1016 at this temperature.
How many mmols of Zn2+ are present in the solution before the titration begins?
What volume of the EDTA solution is needed to reach the equivalence point?
What is the conditional formation constant for Zn at this pH?
What is the pZn of the analyte solution before the titration begins?
What is the pZn of the solution after 15 mL of titrant have been added?
What is the pZn at the equivalence point of the titration?
What is the pZn of the solution after 30 mL of titrant have been added?
In: Chemistry
A 0.4775 g sample of pewter, containing tin, lead, copper, and zinc, was dissolved in acid. Tin was precipitated as SnO2·4H2O and removed by filtration. The resulting filtrate and washings were diluted to a total volume of 200.0 mL. A 20.00 mL aliquot of this solution was buffered, and titration of the lead, copper, and zinc in solution required 35.98 mL of 0.001455 M EDTA. Thiosulfate was used to mask the copper in a second 25.00 mL aliquot. Titration of the lead and zinc in this aliquot required 34.00 mL of the EDTA solution. Finally, cyanide was used to mask the copper and the zinc in a third 30.00 mL aliquot. Titration of the lead in this aliquot required 27.43 mL of the EDTA solution. Determine the percent composition by mass of each metal in the pewter sample.
In: Chemistry
|
Carbonic acid (H2CO3) is a weak diprotic acid with
Ka1=4.43×10−7 and Ka2=4.73×10−11. When sodium
bicarbonate (NaHCO3) is titrated with hydrochloric acid (HCl), it
acts as a weak base according to the equation
NaHCO3(aq)+HCl(aq)→H2CO3(aq)+NaCl(aq) Suitable indicators are those that change color within the pH range for the equivalence point of a specific titration. The expected pH at the equivalence point can be calculated using pKa values. Suitable indicators for use in titrating carbonic acid or carbonate solutions are methyl orange and phenolphthalein. |
Part A What volume of 0.130 M HCl is required for the complete neutralization of 2.00 g of NaHCO3(sodium bicarbonate)? What volume of 0.170 M HCl is required for the complete neutralization of 1.50 g of Na2CO3(sodium carbonate)? A sample of NaOH (sodium hydroxide) contains a small amount of Na2CO3 (sodium carbonate). For titration to the phenolphthalein endpoint, 0.190 g of this sample requires 23.98 mL of 0.100 MHCl. An additional 0.700 mL of 0.100 M HCl is required to reach the methyl orange endpoint. What is the percentage of Na2CO3 by mass in the sample? |
In: Chemistry
CCl F is considered to be environmentally safe and is used as a refrigerant. The heat of vaporization of CCl F is 289 J/g. What mass of this substance must evaporate in order to freeze 2 moles of water initially at 20°C? The heat of fusion of water is 334 J/g and the specific heat of water is 4.18 J/g-K.
In: Chemistry
Solid carbon can react with gaseous water to form carbon monoxide gas and hydrogen gas. The equilibrium constant for the reaction at 700.0 K is Kp=1.60×10−3.
. If a 1.55-L reaction vessel initially contains 153 torr of water at 700.0 K in contact with excess solid carbon, find the percent by mass of hydrogen gas of the gaseous reaction mixture at equilibrium.
mH2/mH2+mCO+mH2O =
In: Chemistry