Recent Homework Questions About Chemistry
Barium-122 has a half-life of 2 minutes. If 10.0 g of Ba-122 are produced in a nuclear reactor how much Ba-122 will remain 10 minutes after production ceases? Question 11 options: 2.50 g 1.25 g 0.625 g 0.313 g
Tuesday, December 2, 2014 at 3:32pm
The half-life of I-131 is 8.00 days. If a medical treatment involves a dose of 400. mg of I-131, how much of the isotope remains after 48 days? 3.125 mg 6.25 mg 12.5 mg 25 mg
Tuesday, December 2, 2014 at 3:30pm
carbon dioxide has a henrys law constant of 3.4E-2 mol/l*atm what is the molar concentration of CO2 in water if the partial pressure of CO2 in air is .000387. i know i have to use S=Kh*P but that gives you soluability where do i go from here to find molar concentration of CO2 ...
Tuesday, December 2, 2014 at 2:59pm
26.98 grams of Al and 35.45 grams of Cl2 are reacted according to the equation 2Al + 3Cl2 → 2AlCl3 How many grams of AlCl3 will be formed assuming 100% yield? it says the answer is supposed to be 26.98g but cannot seem to reach that. I just want to know how to get there.
Tuesday, December 2, 2014 at 2:38pm
A reaction requires 0.5 g of pure methyl oleate (density = 0.87g/mL) (MW = 310g/mol). How many mL of 70% pure methyl oleate are needed for the reaction. I don't exactly know how to start this off. I think what I'm supposed to do is multiply the 70% by the molecular ...
Tuesday, December 2, 2014 at 2:10pm
The molar mass of glucose is 180.16g/mol A. How much glucose is needed to make 500 ml of a .44M (.44mol/1L) solution? .44M/L=180.16x.44/100ml=79.27/1000=.07927x500=39.64g/mol/550ml? B What volume of the .44M solution is needed to prepare 1L of a 5% glucose solution? Don...
Tuesday, December 2, 2014 at 1:36pm
Diiodine pentafluoride reacts spectacularly with bromine trifluoride to form iodine pentafluoride, oxygen gas, and liquid bromine. In a particular reaction a 44.00g sample of I2O5 reacts with 58.00g BrF3. What is the mass of the excess reagent? This is what I have so far: ...
Tuesday, December 2, 2014 at 11:44am
How many moles of atoms are contained in 5.60 grams of Sulfur? Can someone help me understand how to work out other problems like these as well? Thank you!!
Tuesday, December 2, 2014 at 9:59am
Given cell Cd | CdCl2 (0.55M) || NaBrO3 (0.34M), NaBr (0.12M), pH=1.20 | Pt 1. How many electrons are transferred? 2. What is E° for the cell? 3. What is E for the cell?
Tuesday, December 2, 2014 at 12:45am
It takes 476 kJ to remove 1 mole of electrons from the atoms at the surface of a solid metal. how much energy (in kJ) does it take ti remove a single electron from an atom at the surface of this solid metal?
Tuesday, December 2, 2014 at 12:11am
Although no currently known elements contain electron in g orbitals in the ground state, it is possible that these elements will be found or that electrons in excited states or known elements could be in g orbitals. For g orbitals, the value of L(lowercase) is 4. What is the ...
Monday, December 1, 2014 at 11:47pm
A student weighs out 15g of the hydrated salt KCl (this is KCl and water) and heats it till a constant mass of 12 grams remains. What percent of the salt was water?
Monday, December 1, 2014 at 11:27pm
To a mixture of NaCl and Na2CO3 with a mass of 1.300 g was added 55.00 mL of 0.243 M HCl (an excess of HCl). The mixture was warmed to expel all of the CO2 and then the unreacted HCl was titrated with 0.100 M NaOH. The titration required 7.40 mL of the NaOH solution. What was ...
Monday, December 1, 2014 at 11:02pm
An electron is excited from the n=1 ground state to the n=3 state in a hydrogen atom. Which of the following statements are true? Correct the false statements to make them true. A. It takes more energy to ionize (completely remove) the electron from n=3 than from the ground ...
Monday, December 1, 2014 at 10:00pm
The decomposition of potassium chlorate (KClO3) is used as a source of oxygen in the laboratory. How much potassium chlorate is needed to produce 10.2 mol of oxygen? Answer in units of mol
Monday, December 1, 2014 at 9:49pm
I'm not sure how to set this question up... A solution containing 0.015M Sr^2+ and Ba^2+ ions is treated with Na2SO4 and a percipitate containing one metal sulfate forms. Assition of the sulfate ion continues until the more soluble sulfate salt just begins to percipitate. ...
Monday, December 1, 2014 at 9:12pm
For the reaction ?CH4+ ?O2 ==> ?CO2+ ?H2O, what is the maximum amount of CO2 (44.0095 g/mol) which could be formed from 3.67 g of CH4 (16.0425 g/mol) and 4.23 g of O2 (31.9988 g/mol)? Answer in units of g I know that you have to balance the equation, so the coefficients 1, ...
Monday, December 1, 2014 at 9:04pm
The homework question is : Calculate the Delta H for the following reaction: C6H6 + O2 -> C + H2O(l) State whether the reaction is exothermic or endothermic. I'm not sure where to go with this but so far I balanced out the formula to this C6H6 + (3/2)O2 -> 6C2 + 3H2O...
Monday, December 1, 2014 at 8:23pm
What mass of solute is present in each aqueous solution? 40 mL of 6.0 mol/L, H2SO4, solution Soo I did: C=n/V 40 mL= 0.04 L C= 6.0 mol/L/0.04 L = 150 mol/L MH2SO4= 2.02 g/mol + 32.07 g/mol + 64 g/mol= 98.09 g/mol mass H2SO4= 150 mol x (98.09g/1 mol) = 14713.5g =1.47 x 10^4 Is ...
Monday, December 1, 2014 at 8:10pm
A student dissolves 22.4 g of sodium phosphate to prepare a 2.98 L solution. Another student then dilutes this solution to 4.90 L. If sodium phosphate completely dissociates, determine the number of mols of each ion in the final solution.
Monday, December 1, 2014 at 7:44pm
i need help on a lab here are the results Mass of empty beaker and glass rod(62.62) Mass of beaker, glass rod, hydrated copper sulfate(66.02) Mass of beaker, glass rod and anhydrous copper sulfate(65.04) Mass of hydrated copper sulfate(3.4) Mass of anhydrous copper sulfate(2....
Monday, December 1, 2014 at 7:24pm
PLEASE HELP CHEMISTRY
CuSO4.xH2O Determine the percent by mass of water in your sample of hydrated copper (II) sulfate. Show your calculations clearly. My work. i got 10% is that correct
Monday, December 1, 2014 at 6:50pm
CuSO4.xH2O Determine the percent by mass of water in your sample of hydrated copper (II) sulfate. Show your calculations clearly. My work. i got 10% is that correct
Monday, December 1, 2014 at 6:21pm
In the following reaction, how many grams of lead(II) nitrate Pb(NO3)2 will produce 425 grams of sodium nitrate (NaNO3)? Pb(NO3)2(aq) + 2 NaBr(aq) PbBr2(s) + 2 NaNO3(aq) The molar mass of Pb(NO3)2 is 331.21 grams and that of NaNO3 is 85 grams.
Monday, December 1, 2014 at 5:43pm
Democritus- example and picture is it an atom and a picture of a atoms that she wants?? Did he rely on experimental evidence to justify his ideas? yes he gave an image of an atom that distinguished them from each other by their shape, size, and the arrangement of their parts
Monday, December 1, 2014 at 4:57pm
A 100.0 mL sample of a 0.200 molar aqueous solution of K2CrO4 was added to 100.0 mL of a 0.100 molar aqueous solution of BaCl2. The mixture was stirred and the precipitate was collected, dried carefully, and weighed. How many grams of precipitate should be obtained? The ...
Monday, December 1, 2014 at 4:50pm
Version A formular: 3Zn(OH)2 + 2Zn(CO)3(s)----------------------------->5ZnO(s)+2CO2(g) +3H2O(g) 105.4mL of Co2(g) was generated with a pressure of 765.5mm Hg for the gas. The temperature of the apparatus was 25.0C. How much zinc oxide would be left in tube if ...
Monday, December 1, 2014 at 2:23pm
Calculate the pH of the solution that is prepared by mixing 26.06g of ammonium iodide (MM=144.942) and 5.08g of ammonia (MM=17.034g) in enough 0.066 M HCI to produce 1.00L of solution. Kb(NH3)=1.76x10^-5 I converted 24.06g and 5.08g to moles and i now I have to set up an ice ...
Monday, December 1, 2014 at 1:09pm
A student places 0.025 moles of solid sulfur and 0.100 moles of nitrogen monoxide gas in a closed 1.00L container and 0°c for several days. Calculate the number of molecules of NO in the 1.00L container after equilibrium is reached, given the following thermodynamic data. ...
Monday, December 1, 2014 at 11:39am
Given the following equation: N2 (g) + 3H2 (g) → 2NH3 (g) ΔH = -92.6 kJ Calculate ΔH (in kJ) for the decomposition of 30.5 g NH3 (g) into N2 (g) and H2 (g)
Monday, December 1, 2014 at 1:00am
In a particular redox reaction, MnO2 is oxidized to MnO4 and Ag is reduced to Ag. Complete and balance the equation for this reaction in acidic solution. Phases are optional.
Monday, December 1, 2014 at 12:10am
1. Suppose that you have 0.500 L of each of the following solutions, and an unlimited supply of water. (Note: C9H7NHBr is a salt containing the ions C9H7NH+ and Br− and C9H7N is quinoline, an organic base with pKb = 6.24 at 298 K. If you like, you may represent C9H7NH+ ...
Sunday, November 30, 2014 at 11:10pm
Sodium vapor lamps are used in Chicago to light city streets. The light emitted (given off) by these lamps has a λ of 5.9 x 10-7 m. What is the λ in cm? What is the λ in nanometers (nm) [1 meter = 1 x 109 nm]? What is the ν of this radiation? In what region...
Sunday, November 30, 2014 at 10:03pm
I need chemistry help. I think 1. c, 2.b, & 3.a (please tell me why or why not and help me set up the problems if possible) 1.) The following half reaction has been balanced except for the electrons. How many and where should the electrons be included? 14 H+(aq) + Cr2O72-(aq...
Sunday, November 30, 2014 at 9:10pm
To 1.0 ml of 1.5%NaCl, water is added to a final volume of 100ml. What is the molarity NaCl of this final solution? 1.5g/100ml I do not know where to go from here?
Sunday, November 30, 2014 at 8:45pm
If you place 10.0 L of propanol (C3H8O) in a sealed room that is 3 m long, 2.75 m wide, and 2.5 m high, will all the propanol evaporate? If some liquid remains, how much will there be? The vapor pressure of propanol is 10.7 torr at 25 °C, and the density of the liquid at ...
Sunday, November 30, 2014 at 8:35pm
I'm looking for a video of a chemical reaction that can help me answer these questions What are the names of the reactants and products and their states @ room temperature? What type of reaction is it?
Sunday, November 30, 2014 at 8:32pm
Bromine has two naturally occurring isotopes, the first of which is 79Br with a mass of 78.904 amu and an abundance of 50.54%. Calculate the mass of the other isotope.
Sunday, November 30, 2014 at 8:12pm
In order to standardize a KMnO4 solution, 0.2848 g Fe(NH4)2(SO4)2·6H2O was dissolved in 25 mL 0.18 M H2SO4. The KMnO4 solution was added to the Fe(NH4)2(SO4)2·6H2O solution until a pale pink color persisted. The titration took 24.2 mL of KMnO4 solution. What is ...
Sunday, November 30, 2014 at 8:06pm
What volume of H2 gas (in liters), measured at 23 °C and 678 torr, can be obtained by reacting 7.59 g of zinc metal with 124 mL of 0.302 M HCl? Zn + 2HCl --> ZnCl2 + H2
Sunday, November 30, 2014 at 7:46pm
what are the diff b/in: 12. Dilute to and dilute with 13. Warm, boil 14. Heat almost to boiling 15. Heat just to boiling 16. Evaporate to 17. Evaporate to almost dryness 18. Concentrate the volume to 12. I know the meaning of dilute its reducing the concentration but idk ...
Sunday, November 30, 2014 at 7:39pm
Hi, I'm trying to solve for the radius of the sphere. This is the correct steps: 8.27*10^-29 = 4/3 pi * r^3 r^3 = 2.0225 * 10^-29 cu meters When I do 8.27x10^-29 / 4/3 pi, I don't get the answer 2.0225x10^-29 Can you tell me what I'm doing wrong?
Sunday, November 30, 2014 at 7:28pm
Determine how many milliliters of 0.310 M HClO4 will be required to neutralize 52.37g Ca(OH)2 according to the reaction: 2HClO4 + Ca(OH)2 ---> Ca(ClO4)2 + 2 H2O
Sunday, November 30, 2014 at 7:02pm
Consider the reaction for the production of NO2 from NO: 2 NO(g) + O2(g) = 2 NO2(g) a)If 84.8L of O2(g), measured at 35 degrees Celsius and 632mm Hg, is allowed to react with 158.2g of NO, find the limiting reagent. b) If 97.3L of NO2 forms, measured at 35 degrees Celsius and ...
Sunday, November 30, 2014 at 6:58pm
The addition of a crystal of sodium chlorate to a sodium chlorate solution containing no undissolved solute causes additional crystals of sodium chlorate to precipitate. The original solution was supersaturated or unsaturated
Sunday, November 30, 2014 at 12:20pm
Calculate the standard entropy, ΔS°rxn, of the following reaction at 25.0 °C using the data in this table. The standard enthalpy of the reaction, ΔH°rxn, is 44.2 kJ·mol1. C2H4(G)+H20 ---> C5H5OH ΔS°rxn= ______ J*K^-1*mol^-1 ...
Sunday, November 30, 2014 at 12:38am
A solution is prepared that contains 0.0200 M AgNO# and 0.150 M KSCN. What is the equilibrium concentration of Ag+ ion in this solution? The Kf for Ag(SCN)4^3+ is 1.21x10^10 I'm not even sure how to set up this problem? Would I need to do an ice box? Ag(SCN) --> Ag+ + SCN
Saturday, November 29, 2014 at 11:24pm
75.0 mL of a 1.40 M solution is diluted to a volume of 248 mL. A 124-mL portion of that solution is diluted using 165 mL of water. What is the final concentration?
Saturday, November 29, 2014 at 10:47pm
What is the maximum amount of silver in grams that can be plated out of 3.8L of an AgNO3 solution containing 3.3% Ag by mass? (Assume that the density of the solution is 1.02g/mL .)
Saturday, November 29, 2014 at 9:30pm
What would you do in order to solve this question: "The enthalpy of combustion for benzoic acid is -3223.6kj/mol. Use the values of the standard enthalpies of formation of liquid water and CO2 to calculate standard enthalpy of formation of benzoic acid."
Saturday, November 29, 2014 at 9:27pm
I'm working on substitution organic chemistry problems and I just had a question. There's an equation in which a molecule is treated with methanol in an acetone solution. Would the reaction be SN1 or SN2? I thought that it was SN2 because of the aprotic acetone, but ...
Saturday, November 29, 2014 at 8:59pm
During a Breathalyzer Test it was determined that 1.60mg of K2Cr2O7 was consumed by the above reaction. Calculate the number of milligrams of ethanol in the test sample.
Saturday, November 29, 2014 at 8:54pm
Determine the pH (to two decimal places) of a solution prepared by adding 395 mL of 0.0360 M benzoic acid (C6H5COOH) to 12.5 g of sodium benzoate (NaC6H5COO).
Saturday, November 29, 2014 at 8:41pm
Lets assume you have 250 ml of a 1.3M KOH solution and you want to neutralize it with the acid HBr. It takes 350 ml of the HBr solution to do so. What must have been the molarity of the HBr solution? HBr(aq) + KOH(aq) => KBr(aq) + H2O(l) The stoichiometry is already ...
Saturday, November 29, 2014 at 6:59pm
For an H+ concentration, [H+], of 4.3 x 10-4 M, would this be acidic, neutral or basic? Why? I'm assuming that because it is an H+ it would be acidic and H+ means acidic and OH- means base. Is this correct? And is there a better formula for this equation?
Saturday, November 29, 2014 at 6:53pm
nitric acid is composed of HNO3 molecule.A sample of 4.50 g was obtained. calculate the number of oxygen atom in the sample. this is what i do .can u check if i am wrong or miss something answer : mole HNO3 = 4.50g/63 = 0.07 mol mole : no of particle/NA = 0.07x (avogardo ...
Saturday, November 29, 2014 at 5:10pm
hydrogen gas is collected over water at a total pressure of 744 mm Hg at 20.0 C. If the volume of the wet hydrogen is 495 mL, what will the dry volume be at standard conditions? I know that you need to subtract the water vapor pressure from the total and I got 726.45 mmHg. (...
Saturday, November 29, 2014 at 4:35pm
To make a phosphorus fertilizer, agricultural companies use the following reaction: Ca3P2O8 + 2H2SO4 --> CaH4P2O8 + 2CaH4SO6 (fertilizer) If 1.50 * 10^4 grams of H2SO4 are reacted with excess Ca3P2O8 and H2O, how many grams of fertilizer can be made? Hi, I pretty much get ...
Saturday, November 29, 2014 at 3:20pm
titration of 50ml of 0.25ammonia with 0.5M HCL . a) find the initial PH value b) volume of HCL is required to reach the equivalent poinnt c)the ph at the equivalence point
Saturday, November 29, 2014 at 12:59pm
What are the steps to solve this problem? "The enthalpies of combustion of glucose and ethanol are -2813kj/mol and -1369kj/mol, use Hess's law to calculate the enthalpy change when 0.500 kg of glucose is allowed to ferment." Please help.
Friday, November 28, 2014 at 11:18pm
Given that many laboratory gases are sold in steel cylinders with a volume of 43.8 L, What mass (in grams) of argon is inside a cylinder whose pressure is 17810kPa at 24∘C? I've attempted this problem but I'm not getting the correct answer. Please explain if you ...
Friday, November 28, 2014 at 8:09pm
If 14.5g of CO2 gas has a volume of 0.13L at 305K , what is its pressure in millimeters of mercury? I've plugged these values into the equation P=nRT/V but I am having troubles with canceling labels and getting the correct answer. Please explain as much as possible to me!
Friday, November 28, 2014 at 8:08pm
At 2000°C the equilibrium constant for the reaction is Kc = 2.4 ✕ 103. 2 NO(g) equilibrium reaction arrow N2(g) + O2(g) If the initial concentration of NO is 0.160 M, what are the equilibrium concentrations of NO, N2, and O2? I do not even know how to ...
Friday, November 28, 2014 at 5:19pm
At temperatures above 0°C, what is the sign of the change in free energy for the conversion of liquid water to ice? A. Positive B. Zero C. Negative D. Not known
Thursday, November 27, 2014 at 11:18pm
3CuCl2 *2H2O + 2Al = 3Cu + 2AlCl3 + 6H2O Determine the number of grams that should have been produced when 1.25g of copper (2) chloride dehydrate reacts with excess aluminum so i'm not really sure how you're supposed to calculate the number of grams with hydrates?? ...
Thursday, November 27, 2014 at 9:45pm
I don't know how to do this question, or even start it. Please Help. 2 kg copper kettle (specific heat capacity 0.385j/gC) has .0500 kg of water at 20C. How much heat is needed to raise the temperature of the kettle and content to 80C?
Thursday, November 27, 2014 at 9:17pm