Recent Homework Questions About Chemistry
Propylene (or propene in proper IUPAC nomenclature), H2C=CH-CH3, can be reacted by addition polymerization to form polypropylene (PP). The process is initiated with the radical, I*. Choose the image above that properly indicated the location of the unpaired electron, *. What ...
Monday, August 25, 2014 at 1:36am
Select the appropriate electron domain arrangement for ICl3 If you are using electron pairs in your structure, they can be noted with (ep). > I choose trigonal-bipyramidal What is the atomic geometry of this molecule? > I think this only wants the atoms without the lone ...
Sunday, August 24, 2014 at 10:47pm
a)Rank the following 3 tetrachloride compounds in terms of increasing boiling point: carbon tetrachloride (CCl4), methane (CH4), dichloromethane (CH2Cl2) b) Which molecule ( KI or LiF ) has the higher boiling point? c)Select the single most important reason below to justify ...
Sunday, August 24, 2014 at 10:42pm
Jimmy is riding his bike at a speed of 5.5m/s. How long will it take him to go 2 miles? I tried using Dimensional Analysis, but how could you go from 5.5 miles a second to 2 miles?
Sunday, August 24, 2014 at 9:18pm
In an effort to purify the output from a catalytic chemical reaction, C-Cl bonds are to be broken in a gaseous compound by means of LASER radiation. Determine the longest wavelength of radiation still capable of breaking the C-Cl bond. Express your answer in meters. [Given: ...
Sunday, August 24, 2014 at 8:11pm
A 35.0g sample of ethylene glycol is dissolved in 500.0g of water. The vapor pressure of water at 32C is equal to 35.7mm Hg. What is the vapor pressure of the water-ethylene glycol solution at 32C?
Sunday, August 24, 2014 at 2:30pm
Determine the potential (V) by which a proton must be accelerated so as to assume a particle wavelength of 0.0293 nm. ---- This is what I did, dunno if right - wavelength in meters = 2.93*10^-11 m - used DeBroglie relation to find energy lambda = h / mv, v from kinetic energy...
Sunday, August 24, 2014 at 2:08pm
The partial pressure of O2 in your lungs varies from 25 mm Hg to 40 mm Hg. What mass of O2 can dissolve in 1.0L OF water at 25.0oC when the O2 partial pressure is 40. mm Hg?
Sunday, August 24, 2014 at 1:59pm
a) Calculate the number of moles of nitrogen dioxide, NO2, that could be prepared from 79.0 mol of nitrogen oxide and 82.0 mol of oxygen. 2NO(g)+O2(g)⟶ 2NO2(g) b) Identify the limiting reagent and the excess reagent in the reaction. What would happen to the potential ...
Sunday, August 24, 2014 at 10:20am
8-hydroxyquinoline (Q) can complex and precipitate many metals. A mixture of the aluminium and magnesium complexes weighed 1.0843g (MW=459.43; 312.61). When ignited, the mixture decomposed and left a residue of Al203 (MW 101.96) and MgO (MW 40.304) weighing 0.1344g. What is ...
Sunday, August 24, 2014 at 8:09am
Which of following statements correctly describes energy levels? A. Electrons can never move to a higher or lower energy level. B.In it's outermost energy level, oxygen has 4 valence electrons. C. The second energy level holds a maximum of eight electrons. D. The greater ...
Saturday, August 23, 2014 at 9:36pm
Which statement best describes the oxidation numbers of the atoms found in magnesium chloride? A. Magnesium has a 22 oxidation number and chlorine has 1+ oxidation number. B. Magnesium has 1+ oxidation number and chlorine has a 12 oxidation number. C. Magnesium has 22 ...
Saturday, August 23, 2014 at 8:36pm
What is the proper name for MgSO4/H2O? A. Manganese sulfate hexahydrate B. Magnesium sulfite dihydrate C. Magnesium sulfite heptahydrate D. Magnesium sulfate heptahydrate
Saturday, August 23, 2014 at 8:10pm
Which statement correctly describes an atom of the element helium? A. An atom of helium has its valence electrons in it's first energy level. B. An atom of helium most similarly behaves like an atom of hydrogen since it is in the same period. C. An atom of helium has a ...
Saturday, August 23, 2014 at 7:59pm
When water decomposes into oxygen and hydrogen, the mass A. increases B. varies according the number of hydrogen and oxygen molecules that form. C. remains constant D. decreases
Saturday, August 23, 2014 at 7:49pm
The piperazine content of an impure commercial material can be determined by precipitating and weighing the diacetate: (C2H4)2N2H2 + 2 CH3COOH → (C2H4)2N2H2(CH3COOH)2 In one experiment, 0.3126 gram of the sample was dissolved in 25 mL of acetone, and 1 mL of acetic acid...
Saturday, August 23, 2014 at 1:54pm
calculate the amount of water in grams that must be added to 5.00 grams of urea (NH2)2 CO in the preparation of a 16.2 percent by mass, and 26.2 grams of MgCl2 in the preparation of a 1.5 percent by mass solution.
Friday, August 22, 2014 at 5:39pm
hydrogen gas has a Henry's law constant of 1.07e-6 M/mm Hg at 25 Celsius when dissolving in water. if the total pressure of gas (H2 gas plus water vapor) over water is 1.0atm, what is the concentration of H2 in the water in grams per milliliter?
Friday, August 22, 2014 at 9:54am
Full question: An alcohol of molecular formula C4H10O2 contains two OH groups and has an unbranched carbon atom chain. On reaction with excess hot potassium permanganate this alcohol is converted into a compound of molecular C4H6O4 To which carbon atoms in the chain of the ...
Friday, August 22, 2014 at 5:11am
Why neon gas is used in botanical gardens and green houses? Why KrF6 doesn't exist? Why helium can diffuse through rubber,PVC and even glasses? Show two-center-two electron bonds and three-center-four electron bonds in B2H6?
Friday, August 22, 2014 at 2:12am
A mixture of CO and CO2 having a volume of 20 ml is mixed with x ml of oxygen and electrically sparked. The volume after explosion is (16 + x)ml under the same conditions. What would be the residue volume if 30 ml of the original mixture is treated with aqueous NaOH? (a) 12 ml...
Thursday, August 21, 2014 at 5:26pm
1.50g of NaHCO3 is dissolved in 17.1g of water. Express the solubility of NaHCO3 in grams per 100g of solvent and calculate the % composition of NaHCO3 and water.
Thursday, August 21, 2014 at 4:31pm
Hydrogen and chlorine react to yield hydrogen chloride: H2+ Cl2 ( 2HCl. How many grams of HCl are formed from reaction of 3.56 g of H2 with 8.94 g of Cl2? Which reactant is limiting?
Thursday, August 21, 2014 at 1:42pm
one of the following scientists never made any contribution to the development of periodic table? (a)j.jthompson (b)John Newlands (c) Luther Meyer ( d) mendeleev
Thursday, August 21, 2014 at 6:45am
To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 5.3-L bulb, then filled it with the gas at 1.30atm and 27.0 ∘C and weighed it again. The difference in mass was 7.9g . Identify the gas. Express your answer as a ...
Wednesday, August 20, 2014 at 8:16pm
Imagine that you have a 7.00L gas tank and a 3.50L gas tank. You need to fill one tank with oxygen and the other with acetylene to use in conjunction with your welding torch. If you fill the larger tank with oxygen to a pressure of 135atm , to what pressure should you fill the...
Wednesday, August 20, 2014 at 7:30pm
A chemist needs 33.5 g of concentrated sulfuric acid for an experiment. The density of concentrated sulfuric acid is 1.84 g/mL. What volume of the acid is required? I know this is a conversion problem I'm just confused on where the numbers go.
Tuesday, August 19, 2014 at 11:03pm
Justin wants to be the captain of an aircraft carrier when he gets out of school. Which subjects should Justin study to help him prepare for his career? A.biomedical science and meteorology B.oceanography and paleontology C.chemistry and biology D.physics and computer science ...
Tuesday, August 19, 2014 at 2:08pm
Which branches of science do pharmacists need knowledge of to do their job properly? A.physics and chemistry B.biology and chemistry C.chemistry and geology D.physics and computer science Is the answer B?
Tuesday, August 19, 2014 at 1:59pm
At some temperature, the reaction PCl3(g)+Cl2(g)====PCl5(g) is at equilibrium when the concentration of PCl3, Cl2, and PCl5 are 10, 9.0, and 12 mol/L, respectively. Calculate the value of Kc for this reaction at that temperature.
Tuesday, August 19, 2014 at 8:11am
A student measures k for a certain blue due to be 19.4 m^-1 at 560 nm. What is the molarity of the dye in a solution with an absorbance of .118 at this wavelength ?
Tuesday, August 19, 2014 at 7:41am
Equilibrium constant K for some reaction at temperature 300K was found to be 100 .Calculate equilibrium for same reaction at 400K if R= 8.23 change in enthalpy is 5000J
Monday, August 18, 2014 at 9:23am
Lovastatin is an anti-cholesterol drug that can be easily extracted from oyster mushrooms. A 291 mL lovastatin solution with a concentration of 0.001479 mol L-1 was extracted from 50 g of dried oyster mushrooms. Calculate the percentage of lovastatin in the mushrooms. ...
Sunday, August 17, 2014 at 9:00pm
if the wavelength of the first line in the balmer series in a hydrogen spectrum is 6863A .calculate the wavelength of the line in the lyman series in the same spectrum
Sunday, August 17, 2014 at 5:16am
an endothermic reaction a to b has an activation energy of 15 kcal per mol and heat of reaction 5 kcal per mol the activation energy for the reaction b to a will be ?
Sunday, August 17, 2014 at 12:56am
A cow weighing 1317 slug can yield10% steak. Steak may contain 5.8 % fat. How many milligrams of fat can you get from 0.548 slug of steak? (1 slug = 14.59 kg) Answer in units of mg I started the conversion by converting slugs to kg, but I didn't know what to do after that...
Saturday, August 16, 2014 at 12:44am
1) 1.12 dm3 of a gas at STP is found to weigh 3.55g.Find molecular weight and vapour density of gas 2)5.6 dm3 of a gas at STP weighs 11g Find out its relative molecular mass & vapour density
Friday, August 15, 2014 at 10:19am
In an experiment, at a total pressure of 10atm and 400 degree celcius, the equilibrium mixture 2NH3=N2+3H2 the ammonia was found to have dissociated to the extent of 96%. Calculated Kp for the rxn. (reversible rxn).
Thursday, August 14, 2014 at 4:49am
I am given that volume of an unknown acid is 25 mL, volume of NaOH is 13 mL and concentration of NaOH is 1.0 M. I have a graph of a titration curve where the equivalence point is pH=9 (pH on y axis and volume of NaOH on x axis) How would i find the pKa value as well as the Ka ...
Wednesday, August 13, 2014 at 12:41pm
9. The reaction of 50 mL of N2 gas with 150 mL H2 gas to form ammonia via the equation: N 2(g) + 3H2 (g) → 2NH3 (g) will produce a total of mL of ammonia if pressure and temperature are kept constant
Tuesday, August 12, 2014 at 5:46pm
A 2.00g sample of Fe3O4 is reacted with with 8.00g of O2 to produce Fe2O3. a) What mass of Fe2O3 will be produced? b) What mass of Fe2O3 will actually be produced if the percentage yield for reaction is 85% produced?
Tuesday, August 12, 2014 at 9:42am
Mrs. Gomes found that 40% of students at her high school take chemistry. She randomly surveys 12 students. What is the probability that at most 4 students have taken chemistry? Round the answer to the nearest thousandth. A)0.008 B)0.438 C)0.562 D)0.665
Monday, August 11, 2014 at 6:49pm
College Chemistry II
What is the pH of rainwater at 30C in which atmospheric Co2 has dissolved, producing a constant [H2Co3] of 1.40x10^-5 M? Take into account the auto ionization of water. Im very confused on how to even start this problem
Sunday, August 10, 2014 at 5:03pm
In a high school, 30% of student take physics, 15% of students take chemistry. The rest of students are taking biology. What is minimum student taking biology? A.7 B.8 C.9 D.10 E.11
Sunday, August 10, 2014 at 4:20pm
College Chemistry II
What is the solubility of ZnCO3 at 25C in a buffer solution with a pH of 10.21? ZnCO3 <----> Zn++ + CO3 - CO3-- + H2O ----> HCO3- + OH- pOH = 14 10.21 = 3.79 [OH-] = 1.62x10^-4 M = [CO3--] = [Zn++] Ksp = [Zn++][CO3-] = (1.62x10^-4)( 1.62x10^-4) = 2.63x10...
Sunday, August 10, 2014 at 3:35pm
Calculate the adiabatic flame temperature of burning CH4 (g) at 1 atm when burned with 50% excess air, and the reactants enter at 25oC. Standard heat of formation: Ch4: Hr = -49.963kj/mol CO2: Hr = - 393.25 kJ/mol H20(g) : Hr = - 241.835 kj/mol Heat capacities (J/mol), T in oC...
Sunday, August 10, 2014 at 12:53am
Calculate the molarity of the following aqueous solution of 25.0 grams of MgBr2 in 0.355 L solution? Did I work this right? 25gMgBr2/184.113 gMgBr2 =.1357861748 mol MgBr2 then: .1357861748 mol MgBr2/0.355 L =.382 M
Friday, August 8, 2014 at 2:29pm
Suppose a scientist is doing an experiment to determine the effent of a cancer drug on mice with lymphoma. a)What are some of the variables the scientist should control in the experiment? b)Describe the control group for this experiment. a) I want to say the cancer drug and ...
Friday, August 8, 2014 at 2:16pm
A 25 mL solution of nitric acid was placed in a flask and a few drops of phenolphthalein were added. Dilute sodium hydroxide was added util the indicator changed colour. It was found that 28 mL of the alkali was used. (a) What colour was the solution in the flask at the start ...
Thursday, August 7, 2014 at 11:09pm
HNO3 used as a reagent has a specific gravity of 1.42 g/ mL and contains 70% by strength HNO3. Calculate: Volume of acid that contains 60 g pure acid? Volume of water required to make 1 molar solution from 2 mL concentrated HNO3?
Thursday, August 7, 2014 at 3:22pm
A mixture contains n2o4 and No2 in the ratio 2:1 by volume what is the vapour density of the mixture.Pls answer the question i have been on the question for 2 hrs by now tried solving using mole fraction ideal gas equation an using the formula molar mass /2 but still couldn...
Thursday, August 7, 2014 at 1:51pm
I am to do an equilibrium constant lab and I am supposed to only find the Kc value. i have to find the equilibrium constant for NaHCO3 (s) <--> NaOH (s) + CO2 (g) at 800K. The partial pressure in the bulb reads 420 kPa on the manometer, 1 gram of NaHCO3 was added to the ...
Thursday, August 7, 2014 at 12:24pm
A 10.00-mL sample of 0.1000 M KH2PO4 was titrated with 0.1000 M HCl Ka for phosphoric acid (H3PO4): Ka1= 7.50x10-3 ; Ka2=6.20x10-8 ; Ka3= 4.20x10-10 Calculate the pH after addition of 10.00 mL of HCl to the KH2PO4 solution?
Thursday, August 7, 2014 at 3:11am
Still can't figure this one out-- sorry for reposting, this is the last post, if someone has time to review this question and see if they can figure out how the textbook got 1.0x10^-7 seconds Iodine combines to form I2 in liquid propane solvent with a constant of 1,5 x 10...
Wednesday, August 6, 2014 at 3:27pm
Iodine combines to form I2 in liquid propane solvent with a constant of 1,5 x 10^10 L/mol. The rate is 2nd order. Since the reaction occurs quickly, a flash of light creates an I concentration of .0100M. How long will it take for 95% of the atoms to form I2? This must use a ...
Monday, August 4, 2014 at 10:28pm
10.Thirty students in a chemistry class took a test on which the overall average score was 78. If the average score for 15 of those students was 85, what was the average score for the remaining members of the class? I know that "average" means dividing, but i'm ...
Monday, August 4, 2014 at 7:49pm
Im studying for the MCAT and i found this question in my old chem book. i can't figure out how to derive the formula they are talking about... Nitrogen monoxide reacts with oxygen to give nitrogen dioxide. 2 NO(g)+ O2(g) --> 2 NO2(g) The rate law is -[NO]/...
Monday, August 4, 2014 at 1:31pm