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July 7, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

general chemistry
Copper crystallizes in a face-centered cubic unit cell with an edge length of 362 pm. What is the radius of a Cu atom in pm? What equation do you use?
Tuesday, December 9, 2014 by Anonymous

general chemistry
Methanol has a ΔHvap = 35.3 kJ/mol CH3OH. Calculate the change in heat, q, when 50.0 g methanol condenses? Caution! Is q + or -?
Tuesday, December 9, 2014 by Anonymous

chemistry
How to prepare 250.0 mL of 0.076M NaOH?
Tuesday, December 9, 2014 by Sara

chemistry
What is the entropy change associated with the chemical reaction that occurs when iron oxide is converted to its metal form? Fe2O3(s) + 3CO(g) → 2Fe(s) + 3CO2(g) A. Zero B. Positive C. Negative D. Cannot be determined I think the answer is b or c.
Tuesday, December 9, 2014 by Morgan

chemistry
The enthalpy of formation of C2H5OH is -238.7 kJ/mol. What information does this reveal about the bonds in the molecule? A. Bond formation in C2H5OH from its elements only occurs in cold temperatures. B. Bond formation in C2H5OH from its elements does not occur. C. Bond ...
Tuesday, December 9, 2014 by Morgan

chemistry
The pressure of a gas sample in a rigid container is 810.0 mmHg at 22 oC. What is the pressure, in mmHg, at 50 oC? I have a rough idea on how to solve, but which equation do I use?
Tuesday, December 9, 2014 by adrian

Chemistry
How many liters of stomach acid (pH = 4.000) will be neutralized by a 1.50 g tablet of "Bicar", a commercial tablet which is 50% flavored and 50% NaHCO3? Note that: NaHCO3(s) --> Na+(aq) + HCO3-(aq) and: H+(aq) + HCO3-(aq) --> H20(l) + CO2(g) So far I've ...
Tuesday, December 9, 2014 by John

Chemistry
What is the address of the 11 th electron of magnesium? And how do you determine this?
Tuesday, December 9, 2014 by Kelley

Chemistry
What are some cons of becoming a pharmacologist?
Tuesday, December 9, 2014 by anonymous

chemistry
Suppose a gas sample has a density of 3.68 g/L at STP. What is its density at 25 oC and 19.0 atm?
Tuesday, December 9, 2014 by adrian

Chemistry
How much heat energy, in kilojoules, is required to convert 48.0g of ice at −18.0 ∘C to water at 25.0 ∘C ? Please show all steps. i don't know where to start
Tuesday, December 9, 2014 by Anna

chemistry
Suppose a gas sample occupies 14.9 L at STP. What is its volume at 400 K and 0.87 atm? which equation would you use for this?
Tuesday, December 9, 2014 by adrian

chemistry
The total phosphate concentration in a blood sample is determined by spectrophotometry to be 3.0×10−3 M. The pH of the blood sample is 7.45, What are the concentrations of H2PO4− and HPO42- in the blood? Pka for the phosphate system is 7.198
Tuesday, December 9, 2014 by India

Analytical Chemistry
Calculate the ppm of the sodium ions when 2.91 g of sodium triphosphate are added to 2.33 L of solution. I earnestly have no idea how to solve this...
Tuesday, December 9, 2014 by Ryan

Chemistry
The rate constant for a second-order reaction is 0.54 M-1s-1. What is the half-life of this reaction if the initial concentration is 0.27 M
Tuesday, December 9, 2014 by anonymous.

chemistry
Using the following thermochemical data, what is the change in enthalpy for the following reaction? 2H¿(g) + 2C(s) + O¿(g) d C¿HÂOH(l)? C2H5OH(l) + 2O2(g) d 2CO2(g) + 2H2O(l),  DH = -875 kJ C(s) + O¿(g) d CO¿(g),  DH = -394.51...
Tuesday, December 9, 2014 by caleb

Organic Chemistry
Cu++ forms a blue-green complex with tetraphenylporphin in a 1:1 ratio. Say you have 100 mL of a 2.0 x 10^-4 solution of the Tetraphenylporphin. Exactly what weight of CuCl2 must be added to the solution to insure complete complexation without any excess cupric chloride ...
Tuesday, December 9, 2014 by Jessica

Chemistry
Dinitrogen tetraoxide decomposes to give nitrogen dioxide. Calculate the equilibrium concentration of NO2 at 100oC if the equilibrium constant is 0.200 and [N2O4] = 0.800M. N2O4(g) ¡ê 2 NO2(g)
Tuesday, December 9, 2014 by Gail

Chemistry
A liquid has a delta(Hvap) of 35.5 kJ/mol and a boiling point of 122 C at 1.00atm. What is its vapor pressure at 113 C?
Tuesday, December 9, 2014 by Bruce

Chemistry
At a given temperature and pressure how does the magnitude of the heat of vaporization of a substance compare with that of its heat of condensation?
Tuesday, December 9, 2014 by Bruce

Chemistry - University
Pentane (C5H12) and hexane (C6H14) form an ideal solution. The vapour pressure of pentane at 25oC is 511 mmHg and that for hexane is 150 mmHg. A solution is prepared by mixing pentane (density = 0.63 g/mL) and hexane (density = 0.66 g/mL). The mole fraction of hexane in the ...
Tuesday, December 9, 2014 by Gab

chemistry
Why an atom is electrically neutral ?
Tuesday, December 9, 2014 by Haseeb raja

Chemistry
Which solution has the lower freezing point? 11.0 g of methanol in 100. g of water OR 22.0 g of ethanol in 200. g of water?
Monday, December 8, 2014 by Bruce

Chemistry
Is the boiling point of 0.01 m potassium fluoride solution higher or lower than that of 0.01 m glucose solution? Explain
Monday, December 8, 2014 by Sean

chemistry
When HgO is heated, it decomposes into elemental mercury and molecular oxygen gas. If 66.0 g of Hg is obtained from 82.0 g of the oxide, what is the percent yield of the reaction?
Monday, December 8, 2014 by MINITRON

chemistry
Iron and oxygen gas can react to form the magnetic oxide of iron Fe3O4. How many grams of Fe3O4 can be made from 13.2 g of O2?
Monday, December 8, 2014 by dave

Chemistry
Which ion in the pair has greater charge density? Explain Choice. Magnesium ion or Barium ion
Monday, December 8, 2014 by guy

Chemistry
Argon makes up 0.93% by volume of air. Calculate its solubility in water a 20 C and 1.0 atm. The henry's law constant for argon under these conditions is 0.0015 mol/L*atm
Monday, December 8, 2014 by guy

chemistry
2C2H6(g)+7O2(g)--> 4Co2 (g)+6H2O(l) A) if 3.00 moles of C2H6 and 9.00 moles of O2 are introducedinto an empty container at 32.0 degree C and then ignited tointiate the above reaction calculate the mass of water that isproduced. B) if the container volume is 675 what mass of...
Monday, December 8, 2014 by Anonymous

chemistry
2C2H6(g)+7O2(g)--> 4Co2 (g)+6H2O(l) A) if 3.00 moles of C2H6 and 9.00 moles of O2 are introducedinto an empty container at 32.0 degree C and then ignited tointiate the above reaction calculate the mass of water that isproduced. B) if the container volume is 675 what mass of...
Monday, December 8, 2014 by Anonymous

Chemistry
I am soo lost on this one, I don't even know where to begin! I have read the chapter and it's just not clicking! If you start your reaction with 0.083 g of salicylic acid, what theoretical yield of acetylsalicylic acid would you predict? If your experimental yield of ...
Monday, December 8, 2014 by anonymous

Chemistry
The LD50 for oxalic acid in rats is 375 milligrams oxalic acid/kilogram of body weight. Assume that the LD50 for oxalic acid in humans is the same and calculate the oxalic acid LD50 dose for a 160lb human? My calculations: 375mg/kg•1kg/2.20lb • 160lb/1 = 27,272.73 mg
Monday, December 8, 2014 by anonymous

Chemistry
To determine the amount of oxalic acid in rhubarb, you chop up and extract 85.2 grams of homogenized rhubarb with hot water. The extract is treated with calcium hydroxide and you isolate 0.6914 grams of solid CaC2O4•H2O. How many grams of oxalic acid were present in the ...
Monday, December 8, 2014 by anonymous

Chemistry
When HgO is heated, it decomposes into elemental mercury and molecular oxygen gas. If 64.0 g of Hg is obtained from 85.0 g of the oxide, what is the percent yield of the reaction? The balanced equation is 2HgO > 2Hg + 02.
Monday, December 8, 2014 by Anonymous

Chemistry
A mixture of gases contains 2.41 moles of O2, 1.24 moles of H2 and 1.92 moles of C. Calculate the partial pressure of gases if the total pressure is 3.0 atm
Monday, December 8, 2014 by Shayne

chemistry
calculate the oh- and h3o+ concentration of a solution that as ph of 12.11. is the soluion acidic, basic or neutral. report you answer to 2 significant figure
Monday, December 8, 2014 by franny

Chemistry
You read a reversible reaction from left to right in the forward direction. This direction shows which of these occurring? a) the reactants forming a product b) the product decomposing to form reactants c) both a and b occurring d) b occurring, followed by a e) none of the ...
Monday, December 8, 2014 by Jennifer

general chemistry
what is the % acid (eq wt=173.8) if 20.07 mL of .1100 N base were required to neutralize .7231 g of sample?
Monday, December 8, 2014 by alysia

Chemistry
50.0 mL of a 0.20 mol/L HCl reacts with 60.0 mL of 0.15 mol/L NaOH. What is the pH of the final solution? I tried writing out the equation: HCl + NaOH = Cl + NaH2O Now, I am not sure of NaH2O is the right product or not.. However, I am still confused on how I can ifnd the ...
Monday, December 8, 2014 by Chachu

Chemistry Help!!
Types of Reactions Worksheet Balance the following equations and indicate the type of reaction taking place: 1) 2 NH3 + 3 I2  N2I6 + 3 H2 Type of reaction: ____________________ 2) 3 Ca(OH)2 + Al2(SO4)3  3 Ca(SO4) + 2 Al(OH)3 Type of reaction: ...
Monday, December 8, 2014 by Theresa

chemistry
What is the value of A in the following nuclear reaction? 212/84Po→208/82Pb+A/ZX
Monday, December 8, 2014 by Ciara

Organic Chemistry
Write out two step-by-step mechanisms for the addition of HI to C7H12. Make sure to include all necessary curved arrows to depict electron pair movement.
Monday, December 8, 2014 by Anonymous

chemistry
63.0 mL of a 1.30 M solution is diluted to a total volume of 248 mL. A 124-mL portion of that solution is diluted by adding 173 mL of water. What is the final concentration? Assume the volumes are additive.
Sunday, December 7, 2014 by Anonymous

chemistry
100.0 mL of a dilute NaCl(aq) solution is heated in an open beaker. After 15 minutes the burner is turned off. Which of the following is true of the resulting solution? a more concentrated than the initial solution b less saturated than the initial solution c less concentrated...
Sunday, December 7, 2014 by jepow

Chemistry
The tomato is dropped. What is the velocity, v, of the tomato when it hits the ground? Assume 94.7% of the work done in Part A is transferred to kinetic energy, E, by the time the tomato hits the ground.
Sunday, December 7, 2014 by Caitlin

Chemistry; stoichiometry
Determine the theoretical yield of silver that is produced if the other product is Copper(II) Nitrate. Copper that reacted: 0.3180 This is what I had: 0.3180g Cu x 1mol Cu/63.5g Cu x 2mol Ag/1mol Cu x 107.87g Ag/1mol Ag = 1.079g Ag (Set up in factor label method)
Sunday, December 7, 2014 by John

chemistry
a radioisotope is called a tracer when it is used to
Sunday, December 7, 2014 by mia

Chemistry
A 500 mL flask has a measured volume of 586.0 mL. A 0.608g sample of an unknown vapor occupies the flask at 373K at a pressure of 0.981atm. Assume the vapor behaves ideally. What is the molecular weight of the unknown vapor?
Sunday, December 7, 2014 by Caroline

Chemistry
A student analyzing 2.000g of Epsom Salt found that it contained 39.0% by mass water. What is the hydration number for this sample?
Sunday, December 7, 2014 by Caroline

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 by Caroline

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 by Rose

chemistry
What is the mass of 4.3 × 10 to the power of15 atoms of nickel (Ni)?
Sunday, December 7, 2014 by danny

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 by Magaly

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 by Rose

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 by Anon

chemistry
What is the volume of solution prepared when 6g of acetic acid is dissolved to prepare 0.25M solution
Sunday, December 7, 2014 by Ahmad ali

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 by Abdul

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 by Mahnoor

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 by Anonymous

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 by Micky

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 by MINNIE

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 by Angel

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 by Anonymous

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 by Anon

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 by Anon

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 by Morgan

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

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 by Paula

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 by Jessica

chemistry
Sodium chloride has properties that are very similar to those of sodium. True or False
Saturday, December 6, 2014 by Jessica

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 by Rachel

chemistry
A metal oxide will form an acid when it is dissolved in water. T/F
Saturday, December 6, 2014 by Rachel

chemistry
When an acid and a base react in a neutralization reaction, the products will be acidic. T/F
Saturday, December 6, 2014 by Rachel

Chemistry
Temperature is a measure of the amount of heat an object contains. T/F
Saturday, December 6, 2014 by Rachel

chemistry
Most alcohols are very safe to ingest. True or False
Saturday, December 6, 2014 by Sarah

Chemistry
As the number of carbons increases, the boiling point of alkanes decrease True or False
Saturday, December 6, 2014 by Sarah

Chemistry
Excited state electrons lose energy when they move to the ground state.
Saturday, December 6, 2014 by Sarah

chemistry
The Arrhenius theory explains why ammonia, NH3, is basic, but the Bronsted-Lowry theory does not. True or False
Saturday, December 6, 2014 by Meghan

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 by Amy

chemistry
Calculate the number of moles in 74.1 g Pb(C2H3O2)2.
Saturday, December 6, 2014 by Meghan

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 by xx

chemistry
The mass of an atom is distributed evenly throughout the atom.
Saturday, December 6, 2014 by Meghan

chemistry
Naturally occurring reactions of oxygen (O2) are always desirable. True or False
Saturday, December 6, 2014 by Taylor

chemistry
When the following equation is balanced, what is the coefficient for Ta? H2 + Ta2O3 → Ta + H2O
Saturday, December 6, 2014 by Taylor

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 by Teresa

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 by Anonymous

chemistry
All polymers made from polyethylene will have the same density.
Saturday, December 6, 2014 by Anonymous

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 by Anon

chemistry
what else could you use the Volhard method in Chemistry for? like is it used in a certain context?
Saturday, December 6, 2014 by xx

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 by David

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 by Rose

chemistry
Can somebody please answer my question.
Saturday, December 6, 2014 by Teresa

chemistry
Why vaporization is a cooling process ?
Saturday, December 6, 2014 by Haseeb

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 by David

Chemistry
'calculate the mass in amu of 2.879 1023 xenon atoms'
Saturday, December 6, 2014 by Teresa

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 by airman

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 by airman

Chemistry
What precipitates form when CuSO4 and H3PO4 added together?
Saturday, December 6, 2014 by Manali

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 by Jenn

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 by Srm

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