Thursday
July 30, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Chemistry
What is the percent by mass of NaHCO3 and KCl in the mixture.
Sunday, February 15, 2015 by Kc

Chemistry
Can someone please explain to me what was John Dalton's experiment that led to his atomic theory? I know it's the electrolysis of water, but I'd appreciate if someone could explain in detail.
Sunday, February 15, 2015 by Lucina

Chemistry
how many grams of ammonium chloride are needed to raise the ammonia level 5 ppm in a 300 gallon system?
Sunday, February 15, 2015 by Cyndy

Organic Chemistry
Gas Chromatography: The internal standard technique is used. A volatile component which does not interfere with the GC analysis (i.e. it gives a separate peak) is added to the sample which is then analyzed. For example, 10.0 mg of D was added to 50.0 mg of the mixture of A, B...
Sunday, February 15, 2015 by Courtney

chemistry
suppose 0.0139g of HNO3 is dissolved in 625 mL of aqueous solution. what is the pH
Sunday, February 15, 2015 by joseph

Chemistry
Why is the gas oils fraction more viscous than the kerosene fraction
Sunday, February 15, 2015 by Victoria

Chemistry
Calculate the molar extinction coefficients for carotene and chlorophyll using the peaks of highest absorption and Beer’s law.Show your calculations.basically solve for e A = ebc Carotene (Yellow) = Highest peak 450 nm and 0.455 absorption A = ebc 0.455 = e*1cm*c? 0.455...
Sunday, February 15, 2015 by John

chemistry
Two-stroke motor boat engines emit a large amount of partially burned fuel into the water. One of the more common chemicals is phenanthrene . The degradation half-life of phenanthrene is about 7.30 days in clear surface waters. If a motor boat emits 97.0 g of phenanthrene ...
Sunday, February 15, 2015 by danny

chemistry
Based on reaction kinetics, which of the following pairs of reactions and reaction rate equations represent elementary reactions? You may choose more than one reaction. Ti + 2Cl2 = TiCl4 Rate = k[Ti][Cl2] 2SO2 + O2 = 2SO3 Rate = k[O2][SO2]2 Na2S + CuSO4 = CuS + Na2SO4 Rate = k...
Saturday, February 14, 2015 by danny

chemistry
The activation energy of a reaction is typically determined by calculating the rate constant for the reaction at two temperatures and then manipulating the Arrhenius equation. If you determine the reaction rate constants for a particular reaction to be 0.0650 /s at 25.0 C and ...
Saturday, February 14, 2015 by danny

chemistry
Suppose 100 moles of a chemical is spilled into a lake. After 15.0 days, the total amount of the chemical in the lake 3.50 moles. Assuming that the reaction followed first order kinetics and no chemical was lost due to advection or volatilization, then what is the rate ...
Saturday, February 14, 2015 by danny

chemistry
Radioactive waste is difficult to dispose of due to the long time periods needed before the radiation effectively disappears. The US protocol is to store the waste for 10 half-lives of the material after which the waste is no longer considered radioactive. After this time, ...
Saturday, February 14, 2015 by danny

Chemistry
1.2048g sample of impure Na2CO3 is dissolved and allowed to react with a solution of CaCl2 resulting CaCO3 after precipitation, filtaration and drying was found to weight 1.0362g. calculate the percentage purity of Na2CO3
Saturday, February 14, 2015 by Ana

Chemistry
6 mol sample of Cu2S is roasted in excess O2 to yield Cu metal and SO2. Calculate the mass of Cu metal produced
Saturday, February 14, 2015 by Ana

chemistry
In which of the following reactions is ΔE closest in value to ΔH? HNO3(aq) + Na2(CO3)(aq) = NaNO3(aq) + H2O(l) + CO2(g) KClO3(s) = KCl(s) + (3/2)O2(g) HCl(aq) + NaOH(aq) = H2O(l) + NaCl(aq) Na(s) + H2O(l) = NaOH(aq) + (1/2)H2(g)
Saturday, February 14, 2015 by danny

chemistry
If the breakdown half-life of a pesticide applied to a farmer’s field is 3.50 days, then what is the rate constant for this reaction? Assume the degradation reaction follows first order kinetics. The units are 1/d.
Saturday, February 14, 2015 by danny

chemistry
Ethylene gas (C2H2) can be formed from the reaction of calcium carbide (CaC2) with water. What is the reaction rate if 14.2 grams of ethylene gas are produced over 4.00 seconds? The units are mol/s.
Saturday, February 14, 2015 by danny

chemistry
Skim milk has a density of 1.028 g/mL. How many grams are needed to get 0.786L?
Saturday, February 14, 2015 by ako

chemistry
A student measured the mass of a solid sample and recorded the mass on his data sheet as 20.587 grams. He recorded his initial volume as 7.9 mL and his final volume as 11.1 mL. Calculate the density of the sample.
Saturday, February 14, 2015 by ako

chemistry
How do I find the initial rate of reaction for 4.)? 2NO(g)+Cl2(g) ---> 2NOCl(g) [NO] (mol/L) [Cl2] (mol/L) Initial Rate (mol/L * min) 1.) 0.20 1.) 0.10 1.) 0.63 2.) 0.20 2.) 0.30 2.) 1.92 3.) 0.80 3.) 0.10 3.) 2.58 4.) 0.50 4.) 0.50 4.) ???
Saturday, February 14, 2015 by mar

Chemistry
75.0 mL of a 1.20 M solution is diluted to a total volume of 248 mL. A 124-mL portion of that solution is diluted by adding 111 mL of water. What is the final concentration? Assume the volumes are additive.
Friday, February 13, 2015 by Daric

chemistry
Upon decomposition, one sample of magnesium fluoride produced 1.66kg of magnesium and 2.56kg of fluorine. A second sample produced 1.29kg of magnesium. How much fluorine (in grams) did the second sample produce?
Friday, February 13, 2015 by sam smith

Chemistry
Helium was heated in a sealed container from 18°C to 36°C. The original pressure of helium was 0.84 atm. Find the new pressure assuming V and n remain the same. I put 0.84 over 18 and set it equal to x over 36. I got 1.7 atm but it says its wrong?
Friday, February 13, 2015 by Jocelyn

Chemistry
75.0 mL of a 1.20 M solution is diluted to a total volume of 248 mL. A 124-mL portion of that solution is diluted by adding 111 mL of water. What is the final concentration? Assume the volumes are additive.
Friday, February 13, 2015 by Daric

Chemistry
1.How much energy is emitted by 1 mol of sodium ions emitting light at this wavelength? Answer in units of kJ. This is what I did for this problem, but my answer is wrong 45.8 mg = 0.0458 g 0.0458 g / (23.0 g/mol) = 0.001991 mol Na 0.001991 mol x (6.02214 x 10^23) = 1.199 x 10...
Friday, February 13, 2015 by Anna

chemistry
While in Europe, if you drive 125km per day, how much money would you spend on gas in one week if gas costs 1.10 euros per liter and your car's gas mileage is 26.0mi/gal ? Assume that 1euro=1.26dollars.
Friday, February 13, 2015 by Lindsey

chemistry
At 29.6 degrees C, pure water has a vapor pressure of 31.1 torr. A solution is prepared by adding 86.7 g of "L" a nonvolatile nonelectrolyte to 390.0 g of water. The vapor pressure of the resulting solution is 27.6 torr. Calculate the molar mass of "L"
Friday, February 13, 2015 by J

chemistry
In Europe, gasoline efficiency is measured in km/L. If your car's gas mileage is 38.0mi/gal , how many liters of gasoline would you need to buy to complete a 142-km trip in Europe? Use the following conversions: 1km=0.6214mi and 1gal=3.78L.
Friday, February 13, 2015 by Lindsey

chemistry
the gases contain 10^22 and 10^23 molecules present in different vessels at the same temperature. the ratio of their average K.E is the correct answer is 1:1 i think please give explanation
Friday, February 13, 2015 by please............

Chemistry
Methanol ---> Normal BP: 64.6°C --> dHvap: 35.3kJ/mol iso-Propanol ---> Normal BP: 82.3°C --> dHvap: 45.4kJ/mol Cyclohexane ---> Normal BP: 80.7°C --> dHvap: 33.1kJ/mol Question: Ethanol has a normal BP of 78.3°C. Why is the normal BP higher ...
Friday, February 13, 2015 by May

Chemistry
The equation for the best fit line was y = -4058.7x + 16.10. Using the equation of the best fit line, calculate the heat of vaporization (delta H) and the NORMAL BOILING POINT (in Celsius) of this volatile liquid. Calculated: dHvap = 33.7kJ/mol ----> I'm really confused...
Friday, February 13, 2015 by May

AP Chemistry
2 Questions (Multi-choice and T/F, though not sure if they're right, and these 2 questions have no correspondence to each other) 1.) a.) Consider the following system at equilibrium where Kc = 1.20E-2 and H° = 87.9 kJ/mol at 500 K. PCl5 (g) <=> PCl3 (g) + Cl2 (g...
Thursday, February 12, 2015 by Ian

AP Chemistry
Consider the following reaction: 2NOBr(g) 2NO(g) + Br2(g) If 0.332 moles of NOBr, 0.377 moles of NO, and 0.375 moles of Br2 are at equilibrium in a 14.6 L container at 429 K, the value of the equilibrium constant, Kp, is ___. [NOBr] = .332mol/14.6 L = .0227 M [NO] = .377mol/14...
Thursday, February 12, 2015 by Ian

Chemistry!!!!
1. For a reaction mechanism to be plausible, what 2 criteria must be met? 2. The reaction between CO and NO2 to produce NO and CO2 is thought to occur in 2 steps. NO2 + NO2 ====> NO + NO3 NO3 + CO =====> NO2 + CO2 The experimental rate law is, R=k[NO2]2 Write the ...
Thursday, February 12, 2015 by Michelle

chemistry
If 0.130 g of p-aminophenol is allowed to react with excess acetic anhydridre , what is the theoretical yield of acetaminophen in moles ?In grams?
Thursday, February 12, 2015 by reem

chemistry
2) why should you use a minimum amount of water to rinse the conical vial while transferring the purified acetaminpophen to the hirsch funnel?
Thursday, February 12, 2015 by reem

Chemistry
What happens when sulphur reacts with iron? Does it make any colours before it turns dark grey? Does it do anything significant that I should need to know? I know that it is an exothermic reaction but is that it? Please help, Thanks.
Thursday, February 12, 2015 by Alice

Chemistry!!!!
1. For a reaction mechanism to be plausible, what 2 criteria must be met? 2. The reaction between CO and NO2 to produce NO and CO2 is thought to occur in 2 steps. NO2 + NO2 ====> NO + NO3 NO3 + CO =====> NO2 + CO2 The experimental rate law is, R=k[NO2]2 Write the ...
Thursday, February 12, 2015 by Michelle

chemistry
I need to identify two terms that can be applied to electrons
Thursday, February 12, 2015 by Victoria

chemistry
I need to identify the two experments that could be used to investigate the effect of the temperature on the rate of reaction
Thursday, February 12, 2015 by Victoria

Chemistry
Given that the initial rate constant is 0.0190s−1 at an initial temperature of 22 ∘C , what would the rate constant be at a temperature of 190 ∘C for the same reaction described in Part A? Activation Energy 32.4kJ/mol
Thursday, February 12, 2015 by Anonymous

Chemistry
Given that the initial rate constant is 0.0190s^-1 at an initial temperature of 20 degrees Celsius, what would the rate constant be at a temperature of 170 degrees Celsius? Activation energy is 32.4kJ/mol
Thursday, February 12, 2015 by Greg

chemistry
Write both Kc and kp for the following reversible reactions: (wdp pg. 738) 2SO2(g) + O2(g) ↔ 2SO3(g) 2NH3(g) + H2SO4(l) ↔ (NH4)2SO4(s) S(s) + H2SO3(aq) ↔ H2S2O3(aq)
Thursday, February 12, 2015 by shalom

chemistry
formic acid is a weak acid with a ka value of 1.8x10^-4 at 25 celsius a solution with a concentration of .424M formic acid is prepared in a laboratory. 1) Write the ionization equation for an aqeous solution of formic acid 2)determine the ph of the solution prepared above. i ...
Thursday, February 12, 2015 by zack

chemistry
Methanol burns in oxygen to produce carbon (iv) oxide and water if 9 grams of methanol are used in the combustion process what mass of water is produced
Thursday, February 12, 2015 by Regina

Chemistry
Please help!! If the density of fresh water at 4 degrees Celsius is 1.00g/mL, determine if the following objects will sink or float in water. 1.) A 200 feet (61m) tall pine tree that weighs 11,200 pounds (5,080 kg) and has a density of 0.88g/mL 2.) One gram of lead that has a ...
Thursday, February 12, 2015 by Tasha

Chemistry 2
Calculate the molality, molarity, and mole fraction of FeCl3 in a 25.7 mass % aqueous solution (d = 1.204 g/mL).
Thursday, February 12, 2015 by Anonymous

Chemistry
The Haber process is used to synthesize ammonia (NH3) from N2 and H2. The change in standard Gibbs free energy is ΔG°rxn = -16 kJ/mol A. Calculate the equilibrium constant for this reaction B. Calculate the ΔGrxn when you have 2 atm of NH3 (g), 2 atm of H2 (g), ...
Thursday, February 12, 2015 by N

Chemistry
name all the possible isomers of methyl nitrobenzoate and nitroacetanilide which can be formed
Wednesday, February 11, 2015 by Ryan

Chemistry
A flexible balloon containing 1.5 mol of... ideal gas at constant pressure of 1.5 at... 100 °C. Calculate the change in intern...‡ (ΔE) of the gas.
Wednesday, February 11, 2015 by N

CHEMISTRY
the grams of sugar (carbohydrate) in a can of cola that has 150Cal and no fat and no protein Express your answer to two significant figures and include the appropriate u
Wednesday, February 11, 2015 by BREE

chemistry
A moon rock collected by a U.S. Apollo mission is estimated to be 4.50 billion years old by uranium/lead dating. Assuming that the rock did not contain any lead when it was formed, what is the current mass of 206Pb per 1.150 g of 238U in the rock? The half-life of 238U is t1/2...
Wednesday, February 11, 2015 by alice

Organic Chemistry
Why does the carotene elute from the column before the chlorophylls?
Wednesday, February 11, 2015 by Ryan

Chemistry
Why does the carotene elute from the column before the chlorophylls?
Wednesday, February 11, 2015 by Ryan

Chemistry
A solution of NaOH(aq) contains 7.7 grams of NaOH in 93 mL of solution. Calculate the pH at 25◦C. ---- 7.7 grams x (1 mol/39.997 grams) = 0.19 mol 0.19 mol/0.093 L = 2.07 M pOH = -log(2.07) = -0.316 ---- Am I doing anything wrong? Why am I getting a negative pOH/pH ...
Wednesday, February 11, 2015 by Edwin

Chemistry
The freezing point of benzene is 5.5°C. What is the freezing point of a solution of 8.30 g of naphthalene (C10H8) in 320. g of benzene (Kf of benzene = 4.90°C/m)?
Wednesday, February 11, 2015 by Anonymous

Chemistry
Why does the carotene elute from the column before the chlorophylls?
Wednesday, February 11, 2015 by Ryan

Chemistry 2
If a gaseous sample contains 74% N2 by volume, what is the solubility of N2 in water at 25°C and 1.0 atm (kH in H2O at 25°C = 7.0 10-4 mol/Latm)?
Wednesday, February 11, 2015 by Priya

Chemistry
A biochemical engineer isolates a bacterial gene fragment and dissolves a 15.1 mg sample of the material in enough water to make 32.7 mL of solution. The osmotic pressure of the solution is 0.340 torr at 25°C. a) What is the molar mass of the gene fragment? b) If the ...
Wednesday, February 11, 2015 by Pooja

chemistry
If 6.20 mol of calcium carbide (CaC2) reacts with an excess of water, how many moles of acetylene (C2H2), a gas used in welding, will be produced? CaC2(s) + 2 H2O(l) Ca(OH)2(aq) + C2H2(g)
Wednesday, February 11, 2015 by nina

Chemistry
N2+3H2-> 2NH3 how many moles of hydrogen are needed to completely react with 2.6 moles of nitrogen?
Wednesday, February 11, 2015 by Kaitlyn

Chemistry
A 35.00 mL sample of water at 30.0°C is placed in an open container with an external pressure of 1.00 atm. 30.0 kJ of heat is added to the water sample. The density of water is 1 g/mL. (a) How many grams of liquid water remain at the end of the process? Like, the equation ...
Wednesday, February 11, 2015 by N

chemistry
what mass of Silver oxide would be required to produce 100.0 g. of silver.
Wednesday, February 11, 2015 by Shannon

Chemistry
Why does the carotene elute from the column before the chlorophylls?
Wednesday, February 11, 2015 by Ryan

Chemistry
A solution of 4-methyl-3-penten-2-one in ethanol shows an absorbance of 0.52 at 236 nm in a cell with a 1-cm light path. Its molar absorptivity in ethanol at that wavelength is 12,600 M^-1 cm^-1. What is the concentration of the compound?
Wednesday, February 11, 2015 by Ryan

Chemistry
What is the (simplified) meaning of Zn(s) + 2MnO2(s) ZnO(s) + Mn2O3(s) [e° = 1.43 V]? Please answer soon, because I will not be in class too much longer and I have no internet access at home. Thank you in advance!
Wednesday, February 11, 2015 by Ani

chemistry
at a given temperature and pressure 20ml of the gas diffuses through a porous membrane in 5 seconds. calculate the volume o carbon dioxide which diffuses in 10 seconds if the vapour density of the gas is 11 a)10√(2) b)20/√(2) c)40√(2) d)10/√(2) correct ...
Wednesday, February 11, 2015 by please............

Chemistry
A solution of 4-methyl-3-penten-2-one in ethanol shows an absorbance of 0.52 at 236 nm in a cell with a 1-cm light path. Its molar absorptivity in ethanol at that wavelength is 12,600 M^-1 cm^-1. What is the concentration of the compound?
Wednesday, February 11, 2015 by Ryan

Chemistry
Why does the carotene elute from the column before the chlorophylls?
Wednesday, February 11, 2015 by Ryan

Chemistry
Why should a mixture to be separated by column chromatography be introduced onto the column in a minimum amount of solvent?
Wednesday, February 11, 2015 by Ryan

Chemistry
I need to make an Orbital diagram for Li2O. Could you help me find a helpful website or something?
Wednesday, February 11, 2015 by Morgan

Chemistry
Calculate the amount of heat (in calories) absorbed when 50.0g of water at 20C spreads over your skin and warms to body temperature, 37C. I don't understand how to figure this out - which number is the specific heat number? 20C or 37C? I know delta temp will be 17C and ...
Wednesday, February 11, 2015 by HighHopes

Chemistry
calculate the density of NH3 at S650mm of Hg
Wednesday, February 11, 2015 by Bill

chemistry
The specific heat of iron is 0.498 J/g °C. If 341 J of heat is added to 154.1 g of iron at 25.0 °C, what is the new temperature of the iron?
Wednesday, February 11, 2015 by paige

chemistry
How can Coulomb's law explain the distribution of electrons.
Tuesday, February 10, 2015 by Morgan

Chemistry
lets say you have an F atom and an Ne+ ion. Which is more stable
Tuesday, February 10, 2015 by Morgan

chemistry
Electrolysis is carried out for 2.00 h in the following cell. The platinum cathode which has a mass of 25.0782 g, weighs 25.8639g after the electrolysis. The platinum anode weighs the same before and after the electrolysis. there is H2SO4(aq) on the anode side and AgNO3(aq) on...
Tuesday, February 10, 2015 by Anonymous

chemistry
How many water molecules would be produced from the dehydration reactions associated with making a protein that has a primary structure consisting of 378 amino acids, and that has a quaternary structure consisting of 2 identical subunits?
Tuesday, February 10, 2015 by kales

chemistry
how do I write the rate of the reaction for the following: Cl(g)+O3(g)-> ClO(g)+O2(g)
Tuesday, February 10, 2015 by mar

chemistry
the half-life of the reaction, at 34 degrees celsius and Ppan=13.2 torr, is 164.0hr. Calculate the rate constant for the reaction. confused on what to do here
Tuesday, February 10, 2015 by mar

Chemistry
If 22 mol of benzene are completely reacted with molecular oxygen, how many moles of carbon dioxide will be produced?
Tuesday, February 10, 2015 by Ellie

Chemistry
If 20.2 mL of base are required to neutralize 29.3 mL of the acid, what is the molarity of the nitric acid solution?
Tuesday, February 10, 2015 by Rachel

chemistry
If the intial rate of the reaction produces 2 moles of water vapor, H2O, per second, what is the rate at which oxygen, O2, is consumed initially?
Tuesday, February 10, 2015 by Bob

chemistry
when it absorbed energy from a 79.4 g sample of water whose initial temperature was 70.1 °C. What is the specific heat of the metal in J/g·°C? How do i get the final temperature of water
Tuesday, February 10, 2015 by lace

chemistry
i want to neutralize a 10 ml 3 molar sulfuric acid using calcium carbonate but don't know how to do the math the explanation confused me. (also i have to use sig fig and uncertainty)
Tuesday, February 10, 2015 by william

chemistry
How many grams of calcium carbonate would it take to neutralize if i have 10ml 3 molar sulfuric acid? (can this be explained in detail?)
Tuesday, February 10, 2015 by william

Chemistry
what mass of lead(II)nitrate can be formed from reaction of 25.0ml of .100M sodium sulfate and 40.0ml of .200M lead(II)nitrate solutions?
Tuesday, February 10, 2015 by Styllista

chemistry
how many grams of calcium bicarbonate would it take to reach a ph of 7 if i have 10ml 3 molar sulfuric acid?
Tuesday, February 10, 2015 by joe

chemistry
I have 120 ml of a 2M NAOH solution. If Ionly use 10 ml the molarity of the 10 ml is stil 2M, correct?
Tuesday, February 10, 2015 by anonymous

chemistry
Considering the reaction i2 h2=2hi energy change =( tive) and give reasons how "HI" will be produced
Tuesday, February 10, 2015 by idiani

chemistry
equal masses of so2 and o2 are kept in a vessel at 27 degrees celcius. the total pressure of the mixture is 2.1atm. the partial pressure of so2 is
Tuesday, February 10, 2015 by please............

chemistry
at 22°C the equilibrium constant, Kc, for the following reaction is 4.66 x 10-3. (1) If 0.800 mol of N2O4 were injected into a closed 1.00-L container at 22°C, how many moles of each gas would be present at equilibrium? (b) If the volume were halved (to 0.500L) at ...
Tuesday, February 10, 2015 by shalom

Chemistry
Determine the Final state and temperature of 100g of water originally at 25 degree C after 50 kJ of heat have been added to it.
Tuesday, February 10, 2015 by Rishi

chemistry
Prove : Gr degree = 383 kj
Tuesday, February 10, 2015 by Anonymous

chemistry
Calculate mole fraction of HCl in a solution containing 24.8% HCl by mass
Tuesday, February 10, 2015 by sahil

chemistry
Ammonium hydrogen phosphate, a common fertilizer, is made from reacting phosphoric acid with ammonia (NH3). If 10.00g of ammonia react, how many grams of fertilizer will be produced?
Tuesday, February 10, 2015 by SAn

chemistry
How much work is done when 2.0 liters of CH4(g) undergoes combustion in excess oxygen at 0 degrees Celsius and 1.00 bar (assuming the volume of water formed is negligible)?
Monday, February 9, 2015 by Anonymous

Chemistry AP
Alright, this time, I know I have not mistyped my answer. Find the initial concentration of the weak acid or base in an aqueous solution of hydrazine (NH2NH2) with a pH of 10.16. Kb = 1.70 ×10−6 Answer in M I've tried going from 10^-pH then using that (as my x...
Monday, February 9, 2015 by Ethan

chemistry
If ∆G˚= -190.60 kJ of the reaction H2+Cl2 <--> 2HCl , what is the ∆G at -10.5˚C of the system if the pressure of H2=3.2atm and the pressure of Cl2=9.7atm and the pressure of HCl= 7.65atm ?
Monday, February 9, 2015 by Cole

Chemistry
For the following reaction 2NO2 -> 2NO +O2 is second order reaction. If the initial concentration of NO2 is 0.098M and the initial rate of disappearance is 2.72e-3 M/sec , what is the value of the rate constant?
Monday, February 9, 2015 by Cole

  1. Pages:
  2. <<Prev
  3. 15
  4. 16
  5. 17
  6. 18
  7. 19
  8. 20
  9. 21
  10. 22
  11. 23
  12. 24
  13. 25
  14. 26
  15. 27
  16. 28
  17. 29
  18. Next>>

Homework Help: Science

Members