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July 24, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Organic Chemistry
A half-life of a H2O2 solution at a certain condition is 4 weeks. You have a 100 mL of 1.00M H2O2 solution. How many moles of H2O2 will be left in the solution after the following weeks? 04 weeks after: moles 08 weeks after: moles 16 weeks after: moles 20 weeks after: moles
Sunday, July 1, 2012 at 6:56pm

Chemistry
To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 2.7L bulb, then filled it with the gas at 1.30 atm and 30.0 C and weighed it again. The difference in mass was 3.9 g. Identify the gas. I used Pv=nRT to get the moles, but ...
Sunday, July 1, 2012 at 6:19pm

chemistry
what mass NaOH is required to react exactly with 25.0 ml of 3.0 M H2S04
Sunday, July 1, 2012 at 5:44pm

chemistry
3h2+n2 makes 2NH3's if I have 4 moles of H2 instead and 2 moles of N2 would I still just say I have 2.0 or 2.7?
Sunday, July 1, 2012 at 1:54pm

chemistry
What is the molality of a solution containing 7.8 g of MgCl2 in 725 g of water?
Sunday, July 1, 2012 at 1:19am

chemistry
How can you precipitate BaCrO4(s) from a solution of barium nitrate and potassium dichromate?
Saturday, June 30, 2012 at 11:27pm

chemistry
the ph of a 1.00*10^-2 M solution of cyanic acid (HOCN) is 2.77 at 25 C. Calculate Ka and pKa for HOCN from this result.
Saturday, June 30, 2012 at 10:02pm

chemistry
Naturally occurring cobalt consists of only one isotope Co59 whose relative atomic mass is 58.9332. A synthetic radioactive isotope of cobalt Co60, relative atomic mass 59.9338, is used in radiation therapy for cancer. A 1.8516 sample of cobalt has an apparent "atomic ...
Saturday, June 30, 2012 at 4:22pm

Chemistry
A 0.22-caliber handgun fires a 27-{\rm g} bullet at a velocity of 765 {\rm m}/{\rm s}. Part A Calculate the de Broglie wavelength of the bullet.
Saturday, June 30, 2012 at 2:37pm

chemistry
the dencity of 3 molal solution of NaOH is 1.110g/mL calculate the molarity of the solution
Saturday, June 30, 2012 at 6:20am

Chemistry
Calculate the volume at s.t.p. occupied by a gas 'Q' originally occupying 153.7cc at 287K and 750mm pressure [vapor pressure of at 287K is 12mm of Hg]
Saturday, June 30, 2012 at 3:38am

Chemistry
Calculate the volume at s.t.p. occupied by a dry gas 'Q' originally occupying 153.7cc at 287K and 750mm pressure [vapor pressure of gas 'Q'at 287K is 12mm of Hg]
Saturday, June 30, 2012 at 3:25am

chemistry
detail how to dilute a stock solution of nitric acid, 81 m HNO3, to prepare 675 ml of a 2.5 M solution
Friday, June 29, 2012 at 4:46pm

Chemistry
How would you find that water is more acidic than ammonia with out using pka values? would you use resonance effect, inductive effect, hybridization effect, or element effect?
Friday, June 29, 2012 at 10:04am

chemistry
How Many H bonds in Oblate Polyhedra?
Friday, June 29, 2012 at 3:43am

Chemistry
Calculate the molarity and normality of a solution containing 9.8 g of H2SO4 on 250 cm cube of the solutiom
Friday, June 29, 2012 at 2:06am

Chemistry
Calculate the volume at s.t.p. occupied by a gas 'Q' originally occupying 153.7cc at 287K and 750mm pressure [vapor pressure of gas 'Q'at 287K is 12mm of Hg]
Friday, June 29, 2012 at 12:36am

Chemistry
3.30 mL of vinegar needs 40.0 mL of 0.150M NaOH to reach the equivalence point in a titration, how many grams of acetic acid are in a 1.10 qt sample of this vinegar?
Thursday, June 28, 2012 at 11:24pm

chemistry
An experiment is set up in which a copper surface is irradiated with high-intensity photons with a wavelength of 15.0nm. Electrons ejected from the surface are found to have a velocity of .548% of c. What is the binding energy of copper's most weakly bound electrons? What ...
Thursday, June 28, 2012 at 11:00pm

chemistry
In the macy's thanksgivingday parade, 2000, there was a new float, the cheerios'bee, buzbee. the jar of honey it was holding contained 36,763L of helium. the honey jar was 1/10 of the body size. What is the volume of the entire float?
Thursday, June 28, 2012 at 3:39pm

chemistry
0.44 gram of a colorless oxide of nitrogen occurs 224 ml at stp. write the molecular formula of the compound
Thursday, June 28, 2012 at 12:54pm

chemistry
Hvap 40.65 kJ/mol Hf -285.83 kJ/mol Hfusion 6.03 kJ/mol specific heat 4.186 J/gC molar mass 18.02 g How much energy is consumed by thawing 4.3 g ice?
Thursday, June 28, 2012 at 11:18am

chemistry
Hvap 40.65 kJ/mol Hf -285.83 kJ/mol Hfusion 6.03 kJ/mol specific heat 4.186 J/gC molar mass 18.02 g How much energy is consumed by thawing 4.3 g ice?
Thursday, June 28, 2012 at 11:18am

chemistry
how many grams of H2O will be produced if 32.0 grams N2O are produced in the reaction ?
Thursday, June 28, 2012 at 10:40am

chemistry
How many molecules are in 15.6 g NO2? Answer in units of molecules
Thursday, June 28, 2012 at 10:09am

chemistry
the volume at s.t.p. occupied by a gas q originally occupying 153.7 cc at 287 k and 750mm pressure, vapour pressure of gas q at 287k is 12 mm of hg
Thursday, June 28, 2012 at 2:58am

Chemistry 2
Chlorine atoms contribute to the destruction of the earth's ozone layer by the following sequence of reactions: Cl + O3 --> ClO + O2 ClO + O --> Cl + O2 Where the O atoms in the second step come from the decomposition of ozone by sunlight: O3 --> O + O2 What is ...
Thursday, June 28, 2012 at 2:28am

Chemistry
Nitrogen Oxides, NOx (mixture of NO and NO2). The NOx in the atmosphere is slowly broken down to N2 and O2 in a first-order reaction. The average half-life of NOx in the smokestack emissions in a large city during daylight is 3.9 hours. (a) Starting with 1.50 mg in an ...
Thursday, June 28, 2012 at 2:26am

chemistry
calculate the volume occupied by 10^22 molecules of a gas 300 k and 760 mm pressure. please help me please...................
Wednesday, June 27, 2012 at 10:29am

chemistry
calculate the volume occupied by 10^22moleculesof a gas 300k and 760mm pressure
Wednesday, June 27, 2012 at 9:36am

chemistry
A compressed gas cylinder of H2 containing 25 l at 200,000 kPa of pressure is emptied due a leak in a gas chromatography laboratory, with the following dimensions: 5 m long, 4 meters wide and 2.5 m height. Calculate the % oxygen and hydrogen in the atmosphere of the laboratory...
Wednesday, June 27, 2012 at 7:33am

chemistry
If a sample of MgCl2 is known to contain 0.100 moles of Mg ions, how many moles of Cl ions are in the salt sample?
Tuesday, June 26, 2012 at 9:16pm

Chemistry
Tube worms that survive near geothermal vents of hydrogen sulfide rely on bacteria living inside them to obtain energy by the oxidation of H2S to SO4^2-. What is the overall change in the oxidation number of sulfur for this reaction?
Tuesday, June 26, 2012 at 8:01pm

Chemistry
When the oxidation-reduction reaction shown here is balanced, how many electrons are transferred for each atom of copper that reacts? Ag^+ + Cu = Ag + Cu^2+
Tuesday, June 26, 2012 at 7:55pm

Chemistry
An impure sample of substance X melts at about 113 degress. Which of the substances could be X and state y Resorcinal 111 degrees Catechol 105 Nitrophenol 114 Butanamide 115 I think it is either catechol or resorcinol because as stated the higher the percentage of impurity the...
Tuesday, June 26, 2012 at 7:41pm

Chemistry
Write the net ionic equation for the reaction that takes place between a solution of magnesium chloride and a solution of sodium hydroxide.
Tuesday, June 26, 2012 at 7:11pm

Chemistry
How would I figure out what is produced during a chemical reaction between 0.5 grams of sodium bicarbonate and 3 grams of citric acid? I know that it produces carbon dioxide and water but my professor said I am missing something from my equation.
Tuesday, June 26, 2012 at 6:49pm

Chemistry
What is the molar concentration of sodium in a 200ml solution prepared from 1.223g of sodium phosphate?
Tuesday, June 26, 2012 at 6:24pm

Chemistry
Silver nitrite, AgNO2 (47.8 mg), was dissolved in water to make 10.00 mL of solution. Then 3.00 mL of that solution was used to make a new solution with a total volume of 1.000 L. What was the concentration of the silver ion in the final solution?
Tuesday, June 26, 2012 at 6:02pm

Chemistry
Silver nitrite, AgNO2 (47.8 mg), was dissolved in water to make 10.00 mL of solution. Then 3.00 mL of that solution was used to make a new solution with a total volume of 1.000 L. What was the concentration of the silver ion in the final solution?
Tuesday, June 26, 2012 at 5:57pm

Organic Chemistry
A lower yield of phosphonium salt is obtained in refluxing benzene than in xylene. Look up the boiling points for these solvents, and explain why the difference in boiling points might influence the yield. I'm not sure how to answer this question. I see that benzene has a ...
Tuesday, June 26, 2012 at 4:24pm

chemistry
determination of the oxalate content in k2 cu(c2o4)2 .2h2o, during standardization of permanganate solution using sodium oxalate, can the titration between Mno4- and C2o42- at 25degree celcius be perform?
Tuesday, June 26, 2012 at 10:52am

Chemistry
How many grams of calcium phosphate are theoretically produced if we start with 10.3 moles of Ca(NO3)2 and 7.6 moles of Li3PO4?
Tuesday, June 26, 2012 at 7:46am

Chemistry
Which of the following metals would be expected to have the most unstable salts? a) sodium b) zinc c) tin d) silver Please define for me what 'unstable salts' are please?
Tuesday, June 26, 2012 at 3:30am

Chemistry
We did a lab to find the atomic mass of Magnesium. We used an eudiometer and HCL and a mg ribbon. Explain in terms of moles, limiting reactants and experimental feasibility, why we use concentrated HCl (12M) instead of 1M or 6M?? Would the calculated atomic mass be higher, ...
Monday, June 25, 2012 at 10:20pm

chemistry
5.0g of magnesium metal reacted with 1000cm3 of 4.5M of HCl solution to produce hydrogen gas. Calculate the amount of HCl left and the number of hydrogen molecules produced
Monday, June 25, 2012 at 4:31pm

chemistry
5.0g of magnesium metal reacted with 1000cm3 of 4.5M of HCl solution to produce hydrogen gas. Calculate the amount of HCl left and the number of hydrogen molecules produced
Monday, June 25, 2012 at 4:17pm

chemistry
What is the percentage purity of sample if 3.92g of mohr's salt react completely with 50 ml N/10 Kmno4 solution
Monday, June 25, 2012 at 3:34am

chemistry
What is the molarity of a saline solution that contains 0.900 g NaCl (58.44 g/mol) dissolved in 100.0 ml of a solution?
Sunday, June 24, 2012 at 10:49pm

chemistry
how do i convert 2.23*10 22 formula units to moles?
Sunday, June 24, 2012 at 10:29am

scince,chemistry
How grams of NACL are present in a 250-g solution containing 9% NACL?
Sunday, June 24, 2012 at 2:29am

College Chemistry
What are the concentrations of Pb2+ and Cu2+ when the cell potential falls to 0.370 V? Given: A voltaic cell consists of a Pb/Pb2+ half-cell and a Cu/Cu2+ half-cell at 25degrees C . The initial concentrations of Pb2+ and Cu2+ are 5.30×10−2 M and 1.60 M, ...
Saturday, June 23, 2012 at 2:45pm

chemistry
Titration of 50.00 mL of 0.0521 M sodium oxalate, Na2C2O4, required 38.71 mL of a potassium permanganate solution: 5 C2O42- + 2MnO4- + 16H+ = 2Mn2+ + 10 CO2 + 8H2O Calculate the molarity of the potassium permanganate solution.
Saturday, June 23, 2012 at 1:03pm

chemistry
A 0.8378 g sample of calcium oxalate is heated to 1000oC, CaC2O4 = CaO + CO + CO2 Calculate (a) the moles of CaO remaining after ignition (b) the mmoles of CO evolved (c) the weight of CO2 produced.
Saturday, June 23, 2012 at 12:49pm

chemistry HELP!
How much of a 0.10 M H2SO4 solution is required to neutralise 1g of NaOH? Express your answer in cm3.
Saturday, June 23, 2012 at 12:39pm

chemistry
a sample of methane contain 4.5x10 the power of24 h atom.calculate the mass methane
Saturday, June 23, 2012 at 2:19am

Chemistry(check)
Please check for me. 1. For the reaction CH3COOH--->CH3COO + H+, which of the following statements is true? CH3COOH is a Brønsted-Lowry acid.<--- CH3COO is an Arrhenius base. CH3COO is a Lewis base. CH3COOH is a Brønsted-Lowry base. 2. Of the metals Pb, Mg...
Friday, June 22, 2012 at 5:29pm

Chemistry
When a mixture of 10 moles of SO2 and 15 moles of O2 was passed over a catalyst, 10 moles of SO3 was formed. how many moles of SO2 and O2 did not enter into combination?
Friday, June 22, 2012 at 11:36am

Chemistry(explain Please)
How would i find the following? I just need an explanation. I'm stuck. I have many other questions like this and i need to know how to do them. The specfic heat of ice is 2.05 J/g. In a calorimeter, 10.0 g of ice melts at 0oC. The enthalpy of fusion of the ice is 334 J/g. ...
Friday, June 22, 2012 at 10:56am

Chemistry
Calculate the pressure, in atmospheres, of 2.80 moles helium gas in a 18.0 liters container at 24 degrees celcius.
Thursday, June 21, 2012 at 9:54pm

chemistry
An 80.0-gram sample of a gas was heated from 25 °C to 225 °C. During this process, 346 J of work was done by the system and its internal energy increased by 8905 J. What is the specific heat of the gas?
Thursday, June 21, 2012 at 9:02pm

Chemistry
A calorimeter contains 30.0 mL of water at 11.0 degrees C. When 1.50 g of X (a substance with a molar mass of 65.0 g/mol) is added, it dissolves via the reaction: X (s)+H2O (l) ---> X (aq) and the temperature of the solution increases to 26.0 degrees C. Calculate the ...
Thursday, June 21, 2012 at 9:00pm

Chemistry
In the following experiment, a coffee-cup calorimeter containing 100. mL of H2O is used. The initial temperature of the calorimeter is 23.0 degrees C. If 3.80 g of CaCl2 is added to the calorimeter, what will be the final temperature of the solution in the calorimeter? The ...
Thursday, June 21, 2012 at 6:56pm

Chemistry (1Question)
This is really confusing. I know how to do the equilibrium which also has to do with reaction rates but they didb't give it to me as a choice. Please Please help me. I post other questions that i answered already but no one answered me. I just needed someone to check them ...
Thursday, June 21, 2012 at 2:58pm

Chemistry
An ice cube of mass 10g at -10C is added to the beaker containing 150mL of water at 88.5C. Assuming no heat is lost to the surrounding; calculate the equilibrium temperature for the liquid after the ice melts.(Heat of fusion for H2O = 6.01 kJ/mol. Heat of vaporization 40.67kJ/...
Thursday, June 21, 2012 at 1:54pm

Chemistry
How would you go about solving an equation like this when all they give you is a equilibrium equation?: Given the standard free energies of formation in Appendix B in the textbook, what is the value of E ^\circ for the cell reaction?
Thursday, June 21, 2012 at 1:00pm

Chemistry
How would you go about solving an equation like this when all they give you is a equilibrium equation?: Given the standard free energies of formation in Appendix B in the textbook, what is the value of E ^\circ for the cell reaction?
Thursday, June 21, 2012 at 12:42pm

chemistry
why the increasing in substrate concentration increase in the rate of reaction of enzymes.
Thursday, June 21, 2012 at 11:51am

Chemistry
Iron (III) oxide is formed when iron combines with oxygen in the air. How many grams of Fe2O3 are formed when 16.7 g of Fe reacts completely with oxygen? a. 12.0g b. 23.9g c. 47.8g d. 95.6g
Thursday, June 21, 2012 at 11:09am

chemistry
a 230.0ml sample of a 0.275 molarity solution is left on a hot plate over night the folowing morning the solution is 1.5 molarity. what volume of solvent has evaportated from the 0.275 molarity solution?
Thursday, June 21, 2012 at 9:16am

chemistry
a 230.0ml sample of a 0.275 molarity solution is left on a hot plate over night the folowing morning the solution is 1.5 molarity. what volume of solvent has evaportated from the 0.275 molarity solution?
Thursday, June 21, 2012 at 9:16am

chemistry
a 230.0ml sample of a 0.275 molarity solution is left on a hot plate over night the folowing morning the solution is 1.5 molarity. what volume of solvent has evaportated from the 0.275 molarity solution?
Thursday, June 21, 2012 at 9:16am

Chemistry(Please Respond)
Willsomeone, please check my answers? (<-----) indicates my answer. 1.A student increases the temperature of a 556 cm³ balloon from 278 K to 308 K. Assuming constant pressure, what should the new volume of the balloon be? 320 cm3 501 cm3 1232 cm3 616 cm3<------ 2. ...
Thursday, June 21, 2012 at 8:10am

Chemistry-please help!
What is the meaning of combining power of elements and radicals?
Thursday, June 21, 2012 at 4:45am

Chemistry-please help!
What is the chemical formula for alluminium hydroxide?
Thursday, June 21, 2012 at 4:45am

Chemistry-please help!
What is the chemical formula for alluminium hydroxide?
Thursday, June 21, 2012 at 4:41am

Chemistry-please help!
What is the meaning of combining power of elements and radicals?
Thursday, June 21, 2012 at 4:37am

Chemistry
If 2.80 kJ of heat is needed to raise the temperature of a sample of metal from 10.°C to 27°C, how many kilojoules of heat will be required to raise the temperature of the same sample of metal from 40.°C to 58°C?
Thursday, June 21, 2012 at 3:34am

Chemistry
If I have storage tank containing 3.8 X 10E5 liters of water that is contaminated with NaOH and has a pH of 10.82. What volume of 0.1 M HCl is required to bring the pH= 7.0?
Thursday, June 21, 2012 at 2:31am

chemistry
An ice cube of mass 10g at -10C is added to the beaker containing 150mL of water at 88.5C. Assuming no heat is lost to the surrounding; calculate the equilibrium temperature for the liquid after the ice melts.(Heat of fusion for H2O = 6.01 kJ/mol. Heat of vaporization 40.67kJ/...
Thursday, June 21, 2012 at 1:44am

chemistry
I have my exam in a little over 7 hours...can anyone help explain how to draw atoms in the Bohr Rutherford and Lewis Dot methods, as well as how to draw them as compounds and ions? My friends are no help, nor is the internet. Please!
Thursday, June 21, 2012 at 12:52am

Grade 9 Chemistry (2)
What is one way in which Noble Gases are different from other elements? a. Noble Gases have low boiling points b. Noble gases have high melting points c. Noble gases have extremely high densities d. Noble gases have unusually high atomic masses Also, what is a 'valence ...
Wednesday, June 20, 2012 at 9:02pm

chemistry
What is the final temperature of 15.0 g water initialy at 5.5 degrees celcius when 1140 J is added?
Wednesday, June 20, 2012 at 4:49pm

chemistry
A plastic cylinder full of acetylene (C2H2) has a rigid volume of 2.92 L and a pressure of 1.80 atm at 20 °C. The cylinder can only withstand a pressure of 5 atm. Left inside a hot car where the temperature can reach 50 °C, is there danger of the cylinder rupturing? If...
Wednesday, June 20, 2012 at 4:47pm

chemistry
If the atmosphere can support a column of mercury 760 mm high at sea level, what hright of a hypothetical liquid whose density is 1.40 times the density of mercy could be supported?
Wednesday, June 20, 2012 at 4:29pm

General Chemistry
A container holds 3 gases: oxygen, carbon dioxide, and helium. The partial pressure of the three gases are 2.00atm, 3.00atm, and 4.00atm, respectively. What is the total pressure inside the container?
Wednesday, June 20, 2012 at 1:06pm

General Chemistry
A gas is collected and found to fill 2.85L at 25.0 degrees Celsius. What will be its volume at standard temperature?
Wednesday, June 20, 2012 at 1:03pm

General Chemistry
A cylinder with a movable piston contains 2.00g of helium,He, at room temperature. More helium was added to the cylinder and the volume was adjusted so that the gas pressure remained the same. How many grams of helium were added to the cylinder if the volume was chanded from 2...
Wednesday, June 20, 2012 at 1:02pm

General Chemistry
A tank of oxygen is under a pressure of about 4.00 x 10^3 kPa. Express this pressure in millimeters of mercury.
Wednesday, June 20, 2012 at 12:58pm

General Chemistry
At STP, a 5.00L flask filled with air has a mass of 543.251g. The air in the flask is replaced with another gas and the mass of the flask is 566.107g. The density of air is 1.29g/L. What is the gas that replaced the air?
Wednesday, June 20, 2012 at 12:57pm

General Chemistry
A 230.0mL sample of a 0.275 M solution is left on a hot plate overnight; the following morning the solution is 1.50M. What volume of solvent has evaporated from the 0.275 M solution? a)42.2 mL b)63.3 mL c)187.8 mL d)230 mL e)272.2 mL
Wednesday, June 20, 2012 at 12:54pm

General Chemistry
If a 14.05g sample of a gas occupies 10.0L at STP, what is the molar mass of the gas at 125 degrees Celsius?
Wednesday, June 20, 2012 at 12:50pm

General Chemistry
What volume of oxygen gas at STP is needed to react with 5.06 mol of C2H4, according to the following equation C2H4 + 3O2 ----> 2CO2 + 2H2O
Wednesday, June 20, 2012 at 12:45pm

chemistry
An unknown sample with a molecular mass of 180.0g is analyzed to yield 40% C, 6.7% H, and 53.3% O. What is the empirical formula and the molecular formula of this compound?
Wednesday, June 20, 2012 at 11:31am

Chemistry
The molar mass of Cl is 35.45 g/mol. What is the mass of the chloride atom in grams.?
Wednesday, June 20, 2012 at 7:16am

Chemistry
Ag2S is an insoluable black solid. Would more solid dissolve, or precipitate once the following are added to the solution. 1. KS-----I know [S] increases, shift to reactants side, precipitate 2. HClO 3. LiOH 4. NH4OH
Wednesday, June 20, 2012 at 2:25am

chemistry
find the specific heat of lead using 200 g of pb at o degrees celcius and placing it in 200 g of water at 60 degrees celcius
Tuesday, June 19, 2012 at 11:36pm

Chemistry
While heating two different samples of water at sea level, one boils at 102°C and one boils at 99.2°C. Calculate the percent error for each sample from the theoretical 100.0°C.
Tuesday, June 19, 2012 at 10:15pm

Chemistry
Methanol(MM=32.04g/mole) is sometimes used as fuel for race cars, since methanol fires are easily extinguished with water. the energy content o methanol is investigated in a high-quality calorimeter for which the heat capacity is known to be 4.5Kj/C. When 17.62g of liquid of ...
Tuesday, June 19, 2012 at 5:28pm

Chemistry
600cm3 of a gas has a pressure of 1200mmHg find its volume if the pressure is reduced to 1001mmHg
Tuesday, June 19, 2012 at 5:21pm

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