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March 31, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Chemistry
A student was isolating copper metal from a copper salt. If the student started with 1.255g of copper (II) sulfate how many grams of copper solid would you expect them to recover?
Sunday, December 7, 2014 at 5:52pm

chemistry. please help drbob222
One of the reactions involved in the smelting of copper sulfide ores involves copper (I) oxide and copper (I) sulfide: 2Cu2O2 + Cu2S ---> 6Cu + SO2 Assuming that 35.00 g of copper (I) oxide is heated with 25.00 g of copper (I) sulfide A) determine which reagent is present ...
Sunday, December 7, 2014 at 5:24pm

chemistry
What is the mass of 4.3 × 10 to the power of15 atoms of nickel (Ni)?
Sunday, December 7, 2014 at 4:26pm

Chemistry
The titration reaction of a solution containing 1.00 g mixture of Na2CO3 and K2CO3 with HCl shows that there are 8.50x10^-3 moles of C03-2. Find the weight percent of Na2CO3 and K2CO3 in the mixture. Please Help!!
Sunday, December 7, 2014 at 2:50pm

chemistry check if my answers are right. drbobzz
Acetylene gas(c2h2) is used in welding. During one job a welder burns 48.0 g of acetylene. Using a balanced equation for the complete combustion of acetylene calculate the following. Equation 2C2H2 + 5O2 ---> 4CO2 + 2H2O A) the mass of oxygen used B) the mass of carbon ...
Sunday, December 7, 2014 at 2:36pm

Chemistry
estimate Delta H for the following reaction C2H4 (g)+3O2(g)→2 CO2(g)+2 H2O(g) So we have (4) C-H bonds and (1) C=C bond or (H = 4*414 + 615= 2271) For oxygen, (3) O=O bonds or (H = 3*502=1506) 2CO2 is (2) O=C=O (H=730*4=2920) 2H2O is (2) H-O-H or (H=4*464=1856) Delta H...
Sunday, December 7, 2014 at 1:04pm

chemistry
What is the volume of solution prepared when 6g of acetic acid is dissolved to prepare 0.25M solution
Sunday, December 7, 2014 at 1:41am

Chemistry
Vitamin K is involved in normal blood clotting. When 2.32 g of vitamin K is dissolved in 25.0 g of camphor, the freezing point of the solution is lowered by 7.78 °C. The freezing point and Kf constant for camphor can be found here. Calculate the molar mass of vitamin K.
Sunday, December 7, 2014 at 12:27am

Chemistry
estimate Delta H for the following reaction C2H4 (g)+3O2(g)→2 CO2(g)+2 H2O(g) So we have (4) C-H bonds and (1) C=C bond or (H = 4*414 + 615= 2271) For oxygen, (3) O=O bonds or (H = 3*502=1506) 2CO2 is (2) O=C=O (H=730*4=2920) 2H2O is (2) H-O-H or (H=4*464=1856) Delta H...
Sunday, December 7, 2014 at 12:03am

chemistry
One of the reactions involved in the smelting of copper sulfide ores involves copper(I) oxide and copper (I) sulfide: 2Cu2O(solid) + Cu2S(solid) ---> 6Cu(solid) + SO2(gas) Assuming that 35.00 g of copper (I) oxide is heated with 25.00 g of copper (I) sulfide. a) Determine ...
Saturday, December 6, 2014 at 9:55pm

chemistry
What mass of carbon dioxide will be produced when 0.250 mol of propane(C3H8) reacts with 25.0 g of oxygen? Write a balanced equation first.
Saturday, December 6, 2014 at 9:43pm

chemistry PLEASE HELP!!!
Acetylene gas (C2H2) is used in welding. During one job, a welder burns 48.0 g of acetylene. Using a balanced equation for the complete combustion of acetylene, calculate the following: What is the balanced equation. The mass of oxygen used? The mass of carbon dioxide produced...
Saturday, December 6, 2014 at 9:37pm

Organic Chemistry
Label the following reaction components as weaker acid, conjugate base and the species that predominate at equilibrium (two may be present for this one) ethylamine + acetone (equilibrium arrows) ethylammonium + acetone enolate Please help!
Saturday, December 6, 2014 at 9:21pm

chemistry
A 5.00 liter vessel contains carbon monoxide, carbon dioxide, hydrogen and water vapor at equilibrium at 980C. The equilibrium partial pressures are 300. torr, 300. torr, 90. torr, and 150 torr respectively. Carbon monoxide is then pumped into the system until the equilibrium ...
Saturday, December 6, 2014 at 8:11pm

chemistry
6. Ligands approaching in a square planar pattern cause some orbitals to be raised in energy. How many orbitals are on the highest energy level? a. A) 1 b. B) 2 c. C) 3 d. D) 4 e. E) 5
Saturday, December 6, 2014 at 7:58pm

chemistry
Conductivity experiments indicate that tetraamminedichloropalladium (IV) chloride is composed of 3 moles of ions per mole of compound. When silver nitrate solution is added to a solution of the palladium compound, 2 moles of silver chloride per mole of compound are ...
Saturday, December 6, 2014 at 7:56pm

Chemistry
If ammonia is manufactured at 356 K, is the reaction spontaneous, given that the enthalpy and entropy change for the reaction are -93 kJ/mol and -198 J/mol K, respectively? A. Yes, the ΔG is -92 kJ/mol. B. No, the ΔG is 92 kJ/mol. C. No, the ΔG is 22.5 kJ/mol. D...
Saturday, December 6, 2014 at 6:59pm

chemistry
The destructive power generated by an explosive mixture results from the rapid expansion of gaseous products. True or False
Saturday, December 6, 2014 at 6:13pm

Chemistry
A sample of oxygen gas occupies a volume of 3.84 L at 269. K. What volume will the sample occupy at 486. K?
Saturday, December 6, 2014 at 6:12pm

chemistry
A sample of oxygen gas occupies a volume of 3.84 L at 269. K. What volume will the sample occupy at 486. K?
Saturday, December 6, 2014 at 6:11pm

chemistry
Sodium chloride has properties that are very similar to those of sodium. True or False
Saturday, December 6, 2014 at 6:03pm

chemistry
The number of protons in an anion must always be ________ the number of electrons. the same as We can’t tell. less than greater than
Saturday, December 6, 2014 at 5:58pm

chemistry
A metal oxide will form an acid when it is dissolved in water. T/F
Saturday, December 6, 2014 at 5:52pm

chemistry
When an acid and a base react in a neutralization reaction, the products will be acidic. T/F
Saturday, December 6, 2014 at 5:49pm

Chemistry
Temperature is a measure of the amount of heat an object contains. T/F
Saturday, December 6, 2014 at 5:48pm

chemistry
Most alcohols are very safe to ingest. True or False
Saturday, December 6, 2014 at 5:44pm

Chemistry
As the number of carbons increases, the boiling point of alkanes decrease True or False
Saturday, December 6, 2014 at 5:43pm

Chemistry
Excited state electrons lose energy when they move to the ground state.
Saturday, December 6, 2014 at 5:27pm

chemistry
The Arrhenius theory explains why ammonia, NH3, is basic, but the Bronsted-Lowry theory does not. True or False
Saturday, December 6, 2014 at 5:21pm

Chemistry
Gaseous methane (CH4) reacts with gaseous oxygen gas (O2) to produce gaseous carbon dioxide (CO2) and gaseous water (H2o) . What is the theoretical yield of carbon dioxide formed from the reaction of 0.16g of methane and 0.83g of oxygen gas?
Saturday, December 6, 2014 at 5:20pm

chemistry
Calculate the number of moles in 74.1 g Pb(C2H3O2)2.
Saturday, December 6, 2014 at 5:12pm

chemistry
How would I calculate the number of moles of AgNO3? I have .0025L but dont I need the Molarity? I have no idea how to find that.
Saturday, December 6, 2014 at 5:02pm

chemistry
The mass of an atom is distributed evenly throughout the atom.
Saturday, December 6, 2014 at 4:55pm

chemistry
Naturally occurring reactions of oxygen (O2) are always desirable. True or False
Saturday, December 6, 2014 at 4:52pm

chemistry
When the following equation is balanced, what is the coefficient for Ta? H2 + Ta2O3 → Ta + H2O
Saturday, December 6, 2014 at 4:46pm

Chemistry
According to his prelaboratory theoretical yield calculations, a student's experiment should have produced 1.41 g of magnesium oxide. When he weighed his product after reaction, only 1.33 g of magnesium oxide was present. What is the student's percent yield?
Saturday, December 6, 2014 at 4:44pm

chemistry
How many grams of CO(g) are in 0.944 L of the gas at 2.26 atm and 257. K?
Saturday, December 6, 2014 at 4:41pm

chemistry
All polymers made from polyethylene will have the same density.
Saturday, December 6, 2014 at 4:39pm

Chemistry
Consider the following data. DeltaHf (Na2O (s))=-414kJ/mol Delta H sublimation(Na)=109 kJ/mol I.E. (Na)=495 kJ/mol Bond Energy (O2) = 495 kJ/mol E.A. (O) = -141 kJ/mol E.A. (O -) = 878 kJ/mol Use this information to calculate the lattice energy of Na2O (s). So, we have the ...
Saturday, December 6, 2014 at 3:47pm

chemistry
what else could you use the Volhard method in Chemistry for? like is it used in a certain context?
Saturday, December 6, 2014 at 2:34pm

AP Chemistry
What percent (by mass) of granulated sugar is fructose, and what percent of it is sucrose? Background: We are doing a colligative properties lab in my class where we are to add 20 grams, 40 grams, 60 grams, and 80 grams of sugar to 100 grams of water, and use the change in the...
Saturday, December 6, 2014 at 12:04pm

chemistry
Acettlene gas (C2H2) is used in welding. During one job, a welder burns 48.0 g of acetylene. Using a balanced equation for the complete combustion of acetylene, calculate the following: Balanced Equation a) the mass of oxygen used b) the mass if carbon dioxide produced c) the ...
Saturday, December 6, 2014 at 11:34am

chemistry
Can somebody please answer my question.
Saturday, December 6, 2014 at 11:21am

chemistry
Why vaporization is a cooling process ?
Saturday, December 6, 2014 at 11:18am

AP Chemistry
What is the Van't Hoff Factor of MgSO4*7H2O? We're doing a colligative properties lab at my school where we dissolve various amounts of MgSO4 in 100 grams of water. What value/range of values should I expect the Van't Hoff Factor to be?
Saturday, December 6, 2014 at 10:41am

Chemistry
'calculate the mass in amu of 2.879 1023 xenon atoms'
Saturday, December 6, 2014 at 10:28am

chemistry
What mass of solid sodium acetate, NaCH3COO, must be added to 2.50 L of an aqueous solution of 0.55 M acetic acid, CH3COOH, in order to make a buffer solution whose pH is 4.50 ? Assume that adding the solid does not change the volume of the solution. Use the simultaneous ...
Saturday, December 6, 2014 at 5:28am

chemistry
At 35°C, Kc = 1.6 X 10-5 M for the reaction 2NOCI(g) 2NO(g) + Cl2 (g)' Calculate the concentrations of all species at equilibrium for each of the following systems. Note any simplifying assumptions made in the calculations. 3.0 mol NO(g) and 1.0 mol ofCl2(g) in a 1.0 L...
Saturday, December 6, 2014 at 5:27am

Chemistry
What precipitates form when CuSO4 and H3PO4 added together?
Saturday, December 6, 2014 at 2:21am

Chemistry
What is the freezing point of a solution that contains 21.1g of urea, CO(NH2)2, in 305mL water, H2O? Assume a density of water of 1.00 g/mL.
Saturday, December 6, 2014 at 1:39am

chemistry
the number of moles is 0.11 moles and the difference in the mass is 3.1 grams.....identify the gas
Saturday, December 6, 2014 at 1:35am

Chemistry
At a total atmospheric pressure of 1.00 atm, the partial pressure of CO2 in air is approximately 4.0×10−4 atm. If at 20 ∘C and a partial pressure of 760 mmHg, the solubility of CO2 in water is 0.169 g/100mL, what is the solubility of CO2 in an open bottle of ...
Friday, December 5, 2014 at 11:09pm

Chemistry
What is the osmolarity of a typical oral rehydration solution (ORS) for infants that contains 95mEq/LNa+ , 25mEq/LK+ , 115mEq/LCl− , and 2.5% glucose? The molecular weight of glucose is 180 amu.
Friday, December 5, 2014 at 11:07pm

Chemistry
A pickling solution is prepared by dissolving 250g of NaCl in 4.0L of water. Calculate the osmolarity of the solution.
Friday, December 5, 2014 at 11:06pm

Chemistry
Ringer's solution, used in the treatment of burns and wounds, is prepared by dissolving 8.6 g of NaCl, 0.30 g of KCl, and 0.33 g of CaCl2 in water and diluting to a volume of 1.00 L. What is the osmolarity of Ringer’s solution?
Friday, December 5, 2014 at 11:04pm

Chemistry
Complete the Bronsted- Lowry reaction, placing each product by its appropriate label. HCO3^-+HNO2 (double arrows) need a spot for acid and for base.
Friday, December 5, 2014 at 10:15pm

Chemistry
The ΔH of the reaction below is -575.13 kJ. Is this reaction spontaneous? 2ZnS + 3O2 + C → 2SO2 + 2Zn + CO2 A. It is not because the ΔH of the reaction is negative. B. It is because the ΔH of the reaction is negative. C. It depends on the temperature ...
Friday, December 5, 2014 at 9:42pm

Chemistry
Oxygen gas may be prepared by decomposing hydrogen peroxide, h2o2, using manganese (IV) oxide catalyst: 2H2O2(liquid) ----> 2H2O(liquid) + O2(gas) Calculate the amount of oxygen that will be produced from 1.35 moles of H2O2 Determine the mass of oxygen gas that can be ...
Friday, December 5, 2014 at 9:40pm

chemistry
Determine the number of bonding electrons and the number of nonbonding electrons in the structure of SeCl2 and SiO2.
Friday, December 5, 2014 at 8:20pm

chemistry
sodium hydroxide and carbonic acid net ionic equation
Friday, December 5, 2014 at 8:00pm

chemistry
potassium hydroxide and perchloric acid net ionic question
Friday, December 5, 2014 at 7:46pm

chemistry
the half-life of a positron is very short. it reacts with an electron, and the masses of both are converted to two gamma-ray photons:
Friday, December 5, 2014 at 7:34pm

chemistry
Consider the reaction: 2H2S(g)⇌2H2(g)+S2(g) An equilibrium mixture of this reaction at a certain temperature was found to have [H2S]= 0.542M , [H2]= 2.64×10−2M , and [S2]= 7.54×10−3M . What is the value of the equilibrium constant at this ...
Friday, December 5, 2014 at 6:04pm

Chemistry
An archeological artifact was subjected to radiocarbon dating. The artifact showed a carbon-14 decay rate of 13.8 disintegrations/ min per gram of carbon. Carbon-14 has a half-life of 5715 years, and currently living organisms decay at the rate of 15.3 disintegrations/ min per...
Friday, December 5, 2014 at 4:45pm

Chemistry
In the reaction between bromine and sodium, a bromine atom gains an electron. What ion is formed? Is the bromine oxidized, or is it reduced?
Friday, December 5, 2014 at 1:49pm

chemistry
How many bonds can each atom make without hybridization? B,N, and O
Friday, December 5, 2014 at 1:47pm

Chemistry (Electrochemistry)
The standard potential for the following galvanic cell is 1.72V : Be(s)|Be2+(aq)||Pb2+(aq)|Pb(s) The standard reduction potential for the Pb2+/Pb half-cell: E = -.13V Calculate the standard reduction potential for the Be2+/Be half-cell. What I know: Be is the anode Pb is the ...
Friday, December 5, 2014 at 11:57am

Chemistry
The solutions of both Ag+ and Zn2+ ions have no color. What does this suggest about their electron configurations?
Friday, December 5, 2014 at 11:35am

chemistry
EDTA: 292.2 1. How would you make 250ml's of a 15% EDTA solution 2.How much of solution 1(above)should be used to make 500ml's of a .1% EDTA solution.
Friday, December 5, 2014 at 10:37am

Chemistry
Merchants usually sell small nuts, washers, and bolts by weight (like jelly beans!) rather than by individually counting the items. Suppose a particular type of washer weighs 0.128 g on the average. What would 130. such washers weigh?
Friday, December 5, 2014 at 9:53am

chemistry
for the reaction A + B C the concentrations of AB, and C are 0.2M, 0.4M and0.)M respectively at 0 minutes. After 30 minutes the concentrations of A and B drop to ).080mM and 0.280M respectively, while the concentration of C rises to 0.120M. Calculate the rate of this reaction.
Friday, December 5, 2014 at 9:17am

chemistry
The reaction for the complete combustion of acetylene is shown below. C2H2(g) + 5/2 O2(g) -----------> 2 CO2(g) + H2O(l) ΔH = -1299 kJ Use this reaction and the data below to calculate the heat of formation for acetylene. ΔHf[H2O(l)] = -285.8 kJ/mol &#...
Friday, December 5, 2014 at 8:09am

chemistry
Why the vapour pressure of water and ethanol is 760 mm of Hg at 100 C and 78.5 C ?
Friday, December 5, 2014 at 7:57am

Chemistry
In the following reaction, how many liters of carbon dioxide will be produced if 250 liters of oxygen is used in the combustion of sucrose given that both gases are at STP? C12H22O11 + 1202 -> 12CO2 + 11H2O I have had other ones in my homework that were very easy but this ...
Friday, December 5, 2014 at 7:41am

chemistry
) Indicate how each of the following errors would affect(increase, decrease, or no change) your calculated value for the molar volume of O2 at STP (assuming that you complete the expiriment otherwise correctly). In each case, explain your answer. A. Your sample was not ...
Friday, December 5, 2014 at 2:14am

Chemistry
Rank these from lowest boiling point to highest. CH4 CH3CH2CO2CH2CH3 CH3(CH2)2C=ONH2 CH3COOH
Friday, December 5, 2014 at 1:29am

Chemistry
How do I do the empirical formula for 37.01% carbon, 2.22% hydrogen, 18.50% nitrogen, and 42.27% oxygen? My teacher gave me the answer (C7H5N3O6), but I can never get that answer.
Friday, December 5, 2014 at 1:23am

chemistry
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 I don't this it is A. I thought it might be c.
Thursday, December 4, 2014 at 11:37pm

chemistry
How many milliliters of 0.50M NaOH solution are required to titrate 20.0mL of a 0.20M H2SO4 solution to an end point?
Thursday, December 4, 2014 at 11:27pm

chemistry
What is the final volume of NaOH solution prepared from 200.0mL of 0.500M NaOH if you wanted the final concentration to be 0.200M ?
Thursday, December 4, 2014 at 11:24pm

chemistry
a balloon is filled with 15 L of an ideal gas of 20C. at this temperature the pressure of the gas is 1520 mm Hg. Suppose that the volume of the gas is reduced to 5 L at 290 K. what is the new pressure of the gas in atmospheres?
Thursday, December 4, 2014 at 9:56pm

Chemistry honors
20 grams magnesium metal react with excess oxygen and 28 grams of magnesium oxide are produced in lab what is percent yield? If 99.8 g of aluminum nitrate are reacted with excess sulfuric acid what would be the theoretical yield in grams of aluminum sulfate? i have done both ...
Thursday, December 4, 2014 at 7:41pm

Chemistry
Given the equation N2(g)+3H2(g)→2NH3(g), what is the total number of moles of NH3 produced when 10 mol of H2 reacts completely with N2? 1. 2.0 mol 2. 3.0 mol 3. 6.7 mol 4. 15 mol
Thursday, December 4, 2014 at 7:36pm

Chemistry
According to the reaction 2Al+3H2SO4→3H2+Al2(SO4)3, the total number of moles of H2SO4 needed to react completely with 5.0 mol of AL is 1. 2.5 mol 2. 5.0 mol 3. 7.5 mol 4. 9.0 mol
Thursday, December 4, 2014 at 7:32pm

chemistry
grams of potassium permanganate are in 2.58 moles i dont get it ? help
Thursday, December 4, 2014 at 7:02pm

chemistry
A sample of 0.250 g of nickel complex was titrated with 0.150 M EDTA. If the titration of the nickel sample required 7.5 mL of EDTA to reach the equivalence point, what is the percent nickel in the sample?
Thursday, December 4, 2014 at 6:50pm

Chemistry
The Ksp of calcium hydroxide, Ca(OH)2, is 4.68 x 10-6 at 289.15K. Calculate the pH of a saturated solution. Here's my work: 4.68 x 10-6= 4s^3 s= 0.0105 -log(0.0105)= 1.98 14-1.98=12.02 The answer is supposed to be 12.324, but I'm not sure what I'm doing wrong. Is ...
Thursday, December 4, 2014 at 6:32pm

chemistry
9.0 g of KCl was dissolved in 300 mL of water in a calorimeter. Calculate the heat of solution in kJ/mol if the temperature dropped by 2.53 K on dissolution. The specific heat of water is 4.184 J/g K
Thursday, December 4, 2014 at 10:52am

chemistry
the number of electrons present in 18 ml of water at 4 degrees celsius? a)6.023*10^24 b)6.023*10^23 c)4.76*10^21 d)4.76*10^20
Thursday, December 4, 2014 at 10:04am

Chemistry
My chemistry is bad. I know these are very easy but I cannot solve them . 1. a) Prepare 200 ml of 2 M HCl solution from stock bottle containing 37% w/w HCl and d = 1.2 (g/ml). MWHCl = 36.5 g b) Calculate M of 37% w/w HCl solution? d= 1.2, then solve the above problem 2. a) ...
Thursday, December 4, 2014 at 4:13am

chemistry
how many milligrams of calcium is in 1.229-g of calcium carbonate?
Thursday, December 4, 2014 at 3:48am

chemistry
what is the mass (by difference) of a sample if the initial mass of the sample in the bottle was 29.89-g and the final mass of the bottle and sample was 22.01-g ?
Thursday, December 4, 2014 at 1:55am

Chemistry
What is the ppm of 4.50mg of ddt in 10kg of seal fat Please show how
Wednesday, December 3, 2014 at 11:34pm

Chemistry
A sample of gas in a cylinder of volume 3.78 L at 318 K and 3.3 atm expands to 6.76 L by two different pathways. Path A is an isothermal, reversible expansion. Calculate the work for Path A. Answer in units of J
Wednesday, December 3, 2014 at 11:30pm

chemistry
Write an equilibrium expression for each chemical equation involving one or more solid or liquid reactants or products. HCHO2(aq)+H2O(l)⇌H3O+(aq)+CHOͨ​2;2(aq) Use A for [HCHO2], B for [H2O], C for [H3O+], D for [CHO−2].
Wednesday, December 3, 2014 at 11:23pm

Chemistry
In the carbon diselenide, CSe2, identify the number of σ and π bonds, the necessary hybridization scheme and the orbital overlap. Thanks
Wednesday, December 3, 2014 at 8:52pm

physical chemistry
A solution is prepared by adding 1g of sugar mannitol (MW 182.2g/g-mole) in 100g of water at 20◦C. (a) Assuming that mannitol and water form an ideal solution, what is the equilibrium vapor pressure of solution? The vapor pressure of pure water is 17.54mmHg at 20◦C
Wednesday, December 3, 2014 at 8:32pm

CHEMISTRY
A solution with a pH of 7 has a [OH1-] of? 0M or 7M???????????????????
Wednesday, December 3, 2014 at 7:41pm

Chemistry
If 325mL of a 0.58 M solution of a propanoic acid (a fatty acid) was mixed with excess glycerol what is, the maximum number of molecules of fat or oil that could result?(you will need Avogadros number = 6.022 X 10 to the 23rd power)....I need to show all work and im completely...
Wednesday, December 3, 2014 at 7:17pm

Chemistry
E=hv E=energy h= Planck's constant =6.626 x 10^-34 v= frequency 1. What is the energy of light having a frequency of 2.28 x 10^12? ( I do have an answer for this but I'm not so sure about it.) 2.What is the energy of light with a wavelength of 2.18 x 10^-5? 3. A photon...
Wednesday, December 3, 2014 at 7:07pm

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