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October 25, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Chemistry
Attachment of [XeF]+ ions with [AsF6]- ions in their compound
Friday, August 22, 2014 at 2:06am

chemistry
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

chemistry
An aqueous solution is 40.0% by mass hydrochloric acid, HCl, and has a density of 1.20 g/mL. The molality of hydrochloric acid in the solution is m.
Thursday, August 21, 2014 at 4:52pm

chemistry
An aqueous solution of cobalt(II) nitrate has a concentration of 0.471 molal. The percent by mass of cobalt(II) nitrate in the solution is %.
Thursday, August 21, 2014 at 4:43pm

chemistry
How many grams of NiI2 are there in 263 grams of an aqueous solution that is 33.5 % by weight NiI2.
Thursday, August 21, 2014 at 4:33pm

Chemistry
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

chemistry
How many grams of NaOH are there in 187 grams of an aqueous solution that is 7.06 % by weight NaOH.
Thursday, August 21, 2014 at 4:22pm

chemistry
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

chemistry
sulphur+iron filings
Thursday, August 21, 2014 at 10:52am

chemistry
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

Chemistry
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

Chemistry
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

Chemistry
An ideal gas cannot be... A. condensed B. cooled C. heated D. compressed
Wednesday, August 20, 2014 at 7:59am

chemistry
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

Science
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

Science
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

chemistry calculations
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

Chemistry
A 8.5 L sample is collected at 45 degrees C. What will the volume be if the temperature is raised to 70 degrees C.
Tuesday, August 19, 2014 at 8:04am

Chemistry
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

CHEMISTRY
H2So4+S2=2S2+H2O
Tuesday, August 19, 2014 at 4:01am

physical science (chemistry)
calculate the number of atoms in 50 dm3 nitrogen gas
Monday, August 18, 2014 at 4:35pm

chemistry
what is the molar concentration of a solution containing 15,0 g of pottasium chloride in 1,30 dm3 of solution
Monday, August 18, 2014 at 12:49pm

chemistry
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

chemistry
A student needs 1.00 mol of H2SO4 for an experiment. How many liters of 0.60 M H2SO4 does she need to obtain?
Monday, August 18, 2014 at 1:37am

chemistry
blance this equestion with partial balincing method:- Zn+HNo3(very dil)
Sunday, August 17, 2014 at 11:14pm

chemistry
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

Chemistry
How would I find the concentration of an unknown acid if I have a Ka value of 3.98x10^-5?
Sunday, August 17, 2014 at 3:46pm

chemistry
calculate the concentration of ammonium nitrate solution.
Sunday, August 17, 2014 at 8:43am

chemistry
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

chemistry
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

chemistry
ferus amonium sulphate reaction with sulphuric acid
Saturday, August 16, 2014 at 4:07am

chemistry
ferusamoniumsulphate reaction with sulphuric acid
Saturday, August 16, 2014 at 3:54am

Chemistry
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

chemistry
How many moles of atoms are there in 32g of sulfur?
Friday, August 15, 2014 at 9:11pm

chemistry
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

chemistry
a radioactive substance decays 10% in 5 days. The amount remains after 20 days?
Friday, August 15, 2014 at 9:22am

science (chemistry)
filter paper is a poor material on which to powder a solid before introducing it into a melting tube .explain why?
Thursday, August 14, 2014 at 6:35pm

chemistry
kc expression for aluminum+hydrochloric acid
Thursday, August 14, 2014 at 8:14am

physical chemistry
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

Chemistry
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

chemistry
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

Chemistry
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

chemistry
Calculate the molarity of sulfuric acid if 25.00 mL of 0.095 mol L NAOH reacts with 26.45 mL of the acid.
Monday, August 11, 2014 at 10:19pm

chemistry
How many grams are there in 2.5 moles of CuSO4.5H2O?
Monday, August 11, 2014 at 10:16pm

math
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

chemistry
Calculate the number of atoms in 3mol helium
Monday, August 11, 2014 at 2:59pm

chemistry
how do i find weight for 0.065 moles of sulphuric acid
Monday, August 11, 2014 at 11:34am

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

chemistry
f 8.77 g of KI are dissolved in enough water to make 4.75 L of solution, what is the molarity of the solution?
Sunday, August 10, 2014 at 4:54pm

math
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

chemistry
express the following in exponential notation : (a) 0.0030
Sunday, August 10, 2014 at 9:08am

Chemistry
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

chemistry
What are the element in leaf ?
Friday, August 8, 2014 at 9:53pm

Chemistry
Can you please explain if it would be possible to calculate the K value if more than one product or reactant in a chemical equation is a gas?
Friday, August 8, 2014 at 2:56pm

Chemistry 2
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

Chemistry
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

chemistry
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

Chemistry
If 5.4 moles of methane react with 3.5 moles of oxygen gas, how much carbon dioxide will be produced? Use the following equation: CH4 + 2O2 = CO2 + 2H20
Thursday, August 7, 2014 at 10:24pm

Chemistry
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

Physical chemistry
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

Chemistry
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

Chemistry
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

chemistry -repost
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

Chemistry
If 0.896 g of a gas occupies a 250 mL flask at 20 degrees Celsius and 760 mm Hg of pressure, what is the molar mass of the gas?
Tuesday, August 5, 2014 at 12:17am

Organic Chemistry
Rank the following compounds in order of increasing acidity. a. H2O, H3O-, Ho- == HO-, H2O, H3O- b. NH3
Monday, August 4, 2014 at 10:49pm

Chemistry
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

math hw
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

chemistry
What is a Reaction that you would expect when acetylsalicylic acid (aspirin) is heated in the presence of a CONCENTRATED acid? Thanks in advance!
Monday, August 4, 2014 at 2:49pm

Chemistry
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

Chemistry
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 1:30pm

Chemistry
I need help i do not know how to do this problem at all. A 30.00 mL sample of 0.1500 M hydroazoic acid (HN3; Ka = 1.9 x 10-5) is titrated with 0.1000 M KOH. Calculate the pH after the following volumes have been added:
Monday, August 4, 2014 at 1:13pm

Chemistry
What is dS (J/K) of the process when 0.5874 moles of H2 gas are compressed from 37.13 L to 29.13 L at constant temperature?
Monday, August 4, 2014 at 1:05pm

chemistry
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 9:36am

chemistry
KNO3+H2SO4=K2SO4+HNO what mass of sulfuric acid in gram is needed for 2 moles of potassium nitrate? how many moles of mitric acid will be produced from 5 moles of sulfuric acid? what mass in gram of potassium sulfate will be produced from 5 moles of potassium sulfate?
Sunday, August 3, 2014 at 9:58pm

chemistry
how many moles of potassium sulfate are produced for each mole of potassium nitrate?
Sunday, August 3, 2014 at 9:04pm

Chemistry
2Na + 2H2O------> 2NaOH + H2 H=-386kJ If 5g of sodium is added to 200g of water in an open container: (A) How much heat is absorbed/released int he reaction? (B)What volume in formed at 22C and 102kPa? (C) If boiling point elevation constant is 0.52K molal what is the ...
Sunday, August 3, 2014 at 6:29pm

Chemistry
A solution made up of 1.00 M NH3 and 0.500 M (NH4)2SO4 has a pH of 9.26. a. Write the net ionic equation that represents the reaction of this solution with a strong acid. b. Write the net ionic equation that represents the reaction of this solution with a strong base. c. To ...
Sunday, August 3, 2014 at 3:58pm

Chemistry
A chemist wants to prepare phosgene, COCl2, by the following reaction: CO(g) + Cl2(g) COCl2(g) He places 2.60 g of chlorine, Cl2, and an equal molar amount of carbon monoxide, CO, into a 10.00 L reaction vessel at 395 °C. After the reaction comes to equilibrium, he adds ...
Sunday, August 3, 2014 at 2:33pm

Chemistry
If you increase the number of moles of gas in a fixed volume container kept as a constant temperature. What happens?
Saturday, August 2, 2014 at 2:14pm

Chemistry- practice question
The answer for this question is ΔHrxn=-441.40174468085 kJ/mol but I don't know how to arrive to that answer. 0.47g of magnesium reacts with 100ml of 1.00 mol/L HCl in the following reaction: Mg(s)+2HCl(aq)-->MgCl2(aq)+H2(g). The heat of reaction is -8537.4J ...
Friday, August 1, 2014 at 2:53pm

Chemistry
The volume of a gas is 76cm3 at 27c and 800mm mercury pressure.what is the volume at s.t.p
Friday, August 1, 2014 at 8:30am

first chemistry
Salicylic acid reacts with acetic anhydride to produce the analgesic drug aspirin and acetic acid. Using a periodic table, calculate the molecular weight of aspirin to 2 decimal places.
Friday, August 1, 2014 at 1:34am

chemistry
If 3.65 g of a compound having a molecular weight of 481.93 g mol-1 is dissolved in water to make a final volume of 142 mL, what is the concentration of the solution in mM? Answer to three significant figures.
Friday, August 1, 2014 at 1:26am

Chemistry
For :H2O(g) --> H(g) + OH(g); At 3000K and P(total)=1.00 atm, from your K value calculate system composition from 1.00 mol H2O(g) and no products initially. The K I got (using Delta G superscript zero = [Delta H superscript zero]-[T* Delta S superscript zero)=]) was 9.5x10...
Thursday, July 31, 2014 at 11:24pm

Chemistry / help
An equal mass of which of the following states of matter could completely fill both a 100 mL or 500 ml container? A. Gas B. Liquid C. Mixture D. Solid
Thursday, July 31, 2014 at 7:57pm

chemistry
a) Calculate the percent ionization of 0.125M lactic acid (Ka=1.4x10^-4) b) Calculate the percent ionization of 0.125M lactic acid in a solution containing 0.00075 M sodium lactate.
Thursday, July 31, 2014 at 12:23pm

Chemistry
Calculate PH of 0.05 M solution of ammonium acetate
Thursday, July 31, 2014 at 5:22am

CHEMISTRY
A mixture of methane and helium is placed in a 2.0 l flask at 27 degrees the partial pressure of methane is 0.72 ATM and the partial pressure of helium is 0.22 ATM . What is the mole fraction of ch4?
Wednesday, July 30, 2014 at 9:48pm

Chemistry
In order to make 500.0mL of a 1.835 M MgCl2 solution, then _______g of MgCl2 is needed. Moles of MgCl2= (1.835M)(0.5L)=0.9175mol Molecular Weight of MgCl2= 95.211 g/mol (0.9175mol MgCl2)(95.211 g/mol)= 87.36g of MgCl2 Did I do this correct?
Wednesday, July 30, 2014 at 7:59pm

chemistry
A sample of nitrogen gas has the temperature drop from 250°C to 150°C at constant pressure. What is the final volume if the initial volume is 310 mL?
Wednesday, July 30, 2014 at 7:50pm

inorganic chemistry
A large number of hydrogen atoms have electrons to the n=4 state.How many possible spectral lines can appear in the emission spectrum as a result of the electron reaching the ground state(n1=1).Diagram all possible pathways for de excitation from nh=4 to nh=1
Wednesday, July 30, 2014 at 7:28pm

chemistry
Which statement is false? The average kinetic energies of molecules from samples of different “ideal” gases is the same at the same temperature. Molecules of a gas undergo many collisions with each other and the container walls. All molecules of an ideal gas have the...
Wednesday, July 30, 2014 at 7:00pm

Chemistry
1. In order to make 250mL of a 0.100 M HNO3 solution from a 15.9 M stock solution, then _____mL if the 15.9 M stock HNO3 solution is needed. M1V2=M2V2, solve for V2. (0.100M * 250mL)/ 15.9M = 1.6mL V2-V1=V 1.6mL-250= -248.4 Did I do this correctly?
Wednesday, July 30, 2014 at 6:15pm

chemistry
consider the reaction 2NaF if you begin with 4.8 mol S and 2.6 mole F, what is the limiting reactant and theorical yield of NaF in moles
Wednesday, July 30, 2014 at 10:57am

Chemistry
how would you prepare 250 mL of 0.69M Al2(SO4)3 solution from a 2.0M Al2(SO4)3 stock solution?
Wednesday, July 30, 2014 at 10:21am

Chemistry
DECOMPOSITION OF NO2 (10/10 points) The decomposition of NO2 at room temperature exhibits the following variation in concentration with time: The concentration of NO2 is expressed in mol/liter, while time is expressed in seconds. [NO2] ln[NO2] 1/[NO2] Time (s) 0.0831 -2.4877 ...
Wednesday, July 30, 2014 at 9:57am

Chemistry
If the sign for delta G is negative (spontaneous process) and sign for delta S is positive (more disorder) for both dissolving processes, how could one be endothermic (positive delta H- NaNO3 dissolves in water) and one be exothermic (negative delta H- NaCH3COO dissolves in ...
Wednesday, July 30, 2014 at 2:23am

Chemistry
Using Hess’s Law with the following data: N2(g) + O2(g) = 2NO(g) Del(H) = 180.7kj 2NO(g) + O2(g) = 2NO2(g) Del(H)= -113.1kj 2N2O(g) = 2N2(g)+ O2(g) Del(H)=-163.2kj Calculate Del(H) for the reaction: N2O(g) + NO2(g) = 3NO(g)
Tuesday, July 29, 2014 at 11:22pm

Chemistry
Calculate the standard enthalpy change for the following reaction at 25 °C.? 2CH3 OH(g) + 3O2(g) -------- 2CO2(g) + 4H2O (g)
Tuesday, July 29, 2014 at 7:42pm

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