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December 20, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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chemistry
qualitative organic analysis lab 1. Why is it important to have clean test tubes before running a test? Before which tests should acetone not be used to clean the test tubes? 2. Why run solubility tests before running the functional group classification tests? 3. Determine ...
Thursday, October 30, 2014 at 1:06am

chemistry
Calculate the concentrations of all species in a 1.22 M Na2SO3 (sodium sulfite) solution. The ionization constants for sulfurous acid are Ka1 = 1.4× 10–2 M and Ka2 = 6.3× 10–8 M.
Thursday, October 30, 2014 at 12:42am

chemistry
Calculate the number of GRAMS of carbon dioxide (CO2) produced when 100 grams of methane (CH4) are completely burned in oxygen (O2).
Wednesday, October 29, 2014 at 11:25pm

Chemistry
Consider the following reaction: 4NH3(g) +5O2(g) -->4NO(g) +6H2O(g) Suppose we have two flasks connected by a stopcock. In one flask, we have 2.0L of NH3(g) at a pressure of .500 atm. In the other flask, we have 1.00L of O2(g) at a pressure of 1.5atm. When the stopcock is ...
Wednesday, October 29, 2014 at 11:20pm

Chemistry
The solubility of aluminum sulfate in water at 20degrees Celcius is 26.7g/100L. Calculate its molarity?
Wednesday, October 29, 2014 at 11:05pm

Chemistry
A student reacted 0.500g of Pb(NO3)2 with 0.750g of KI according to the reaction, Pb(NO3)2(aq) + 2KI(aq)=PbI2(s) + 2KNO3(aq) A) How many moles of Pb(NO3)2 were used? B) How many moles of KI were used? C) How many moles of PbI2 would form, based on the moles of Pb(NO3)2 used? D...
Wednesday, October 29, 2014 at 10:52pm

CHEMISTRY
A student combusted 0.500g of purified aluminum power with excess oxygen in an oxygen atmosphere according to the reaction, 4Al(s) + 3O2(g)= 2Al2O3(s) A) What is the limiting reactant? B) How many moles of Al were used? C) How many moles of Al2O3 would form, based on the moles...
Wednesday, October 29, 2014 at 10:40pm

Chemistry (urgent)
1.Using Nerst, find the E of the cell for the dicromate redox system: A.under standard conditions. B.under neutral solutions instead of acid solutions. 2.Use Nerst and the hydrogen half equation to obtain an expression for pH.
Wednesday, October 29, 2014 at 10:10pm

chemistry
Calculate the theoretical percentage of water present in cobalt (II) chloride hexahydrate, given that the molar mass is 237.93 g/mol and the molar mass of water in the compound is 108.12 g/mol. Question 8 options: 220% 50.5% 6% 45.4%
Wednesday, October 29, 2014 at 9:54pm

chemistry
The solubility of sodium chloride (NaCl) was determined experimentally to be 35.7 g/ 100 g of water (H2O) at 200 C. How many grams of NaCl would dissolve in 50g of H2O at 200 C?
Wednesday, October 29, 2014 at 9:51pm

Chemistry
Calculate the enthalpy change for: C2H4(g) + H2 --> C2H6(g) delta Hrxn: H2(g) + 1/2O2 --> H2O (l) C2H4(g) + 3O2 --> 2H20(l) + 2CO2(g) C2H6(g) + 7/2O2(g) --> 3H20(l) + 2CO2(g) I know I have to flip the third reaction but I dont know what to do next
Wednesday, October 29, 2014 at 8:18pm

chemistry
If you have 22.46 mLs of a gas at STP, how many moles of gas do you have?
Wednesday, October 29, 2014 at 8:15pm

Chemistry
1.Using Nerst, find the E of the cell for the dicromate redox system: A.under standard conditions. B.under neutral solutions instead of acid solutions. 2.Use Nerst and the hydrogen half equation to obtain an expression for pH.
Wednesday, October 29, 2014 at 6:53pm

Chemistry
Explain what would happen to the color of a dilute solution containing FeCl4- if you added a solution of sodium chloride, NaCl.
Wednesday, October 29, 2014 at 5:05pm

Chemistry
A sample of methane (CH4) gas contains a small amount of helium. Calculate the volume percentage of helium if the density of the sample is 0.70902 g/L t 273K and 1.00 atm. I know that the sample is at STP and that the 1 mole of gas under these conditions occupies 22.4L, but ...
Wednesday, October 29, 2014 at 3:42pm

chemistry
2CH3OH(g)→2CH4(g)+O2(g)ΔH=+25​2.8kJ For a given sample of CH3OH, the enthalpy change during the reaction is 82.2kJ . How many grams of methane gas are produced?
Wednesday, October 29, 2014 at 2:57pm

Chemistry
How much heat is required to raise the temperature of 68.0 g of AIF3 from 25 degrees celsius to 80.0 degrees celsius
Wednesday, October 29, 2014 at 2:01pm

chemistry
500g urea aq. Sol. Has mole fraction 0.2 what is molality of sol.
Wednesday, October 29, 2014 at 10:13am

chemistry
At what temperature will the following reaction happen spontaneously, given that ΔH=8.91×103J and ΔS= –219.20 J/K? CaSO4(s) + 2HCl(g) → CaCl2(s) + H2SO4(l)
Wednesday, October 29, 2014 at 10:13am

Analytical Chemistry
Suggest a range of sample masses for the indicated primary standard if it is desired to use between 35 and 45mL of titrant: (a) 0.175 M HClO4 titrated against Na2CO3(CO2 product) (b) 0.085 M HCl titrated against Na2C2O4 Na2C2O4-->Na2CO3+CO CO3(2-)+2H(+)-->H2O+CO2 (c) 0....
Wednesday, October 29, 2014 at 5:41am

Chemistry
By what factor does the volume increase when An ideal gas is allowed to expand from 3.80 L to 32.3 L at constant temperature
Wednesday, October 29, 2014 at 1:52am

Chemistry 400/ Chem 1A
Assuming that the resolution of an electron microscope is equal to the deBroglie wavelength of the electrons used, what is the resolution of an electron microscope (in nm) when the electrons are accelerated to a speed of (5.60x10^5) m/s?
Wednesday, October 29, 2014 at 12:31am

Chemistry
Silver carbonate [AgCar] has a density of 6.077 g/cm3. Calculate the mass (in fg) of carbon atoms [C] present in a AgCar crystal that has a volume of 457.6 Å3.
Tuesday, October 28, 2014 at 11:29pm

Chemistry
If a sample of ammonium sulfate contains 1.75 grams of nitrogen [N] atoms, calculate the mass (in grams) it contains of sulfur atoms [S].
Tuesday, October 28, 2014 at 7:35pm

Chemistry
If you used 2.0mL of 1.0M H2SO4 and 3.0g of NaHCO3 how many moles of CO2 would be produced?
Tuesday, October 28, 2014 at 7:22pm

Chemistry
When you have 50ml of a 0.25M solution of KI in water. What should the final volume be is you want to reduce the concentration to .10M
Tuesday, October 28, 2014 at 7:20pm

Chemistry
Hello. On the homework for my middle school chemistry class, one of the questions asks me to identify "the four classifications of substances". I am having difficulties with this problem.
Tuesday, October 28, 2014 at 7:05pm

Chemistry
The combustion of octane produces carbon dioxide and water. If you start with 10.0 mol of octane, what mass of water (in grams) would you expect to produce?
Tuesday, October 28, 2014 at 6:43pm

chemistry
1. A gas cylinder contains 0.722 mL of hydrogen gas at a pressure of 10.6 atm. If the gas is used to fill a balloon at a pressure of 0.960 atm, what is the volume of the filled balloon?
Tuesday, October 28, 2014 at 5:21pm

chemistry
Why is it important to make sure that the volume of water and the starting temperature are the same in each trial ?
Tuesday, October 28, 2014 at 5:20pm

Chemistry
need the answers to the formulas for the Ionic Compound: DiAmmonium Chromate Also I need the name of the following formula Sr(MnO4)2
Tuesday, October 28, 2014 at 5:01pm

Chemistry
How many atoms of aluminum [Al] are present in a sample of aluminum carbonate [AlCar] weighing 3.45E6 amu?
Tuesday, October 28, 2014 at 4:36pm

chemistry
Calculate the volume of concentrated NaOH solution (which contains 500.00g of NaOH per liter of solution) that you will need to make 1.00L of a 0.100M NaOH solution
Tuesday, October 28, 2014 at 4:26pm

chemistry
Calculate the mass of KHP which will result in an endpoint of 20.00mL when titrated against 0.097M NaOH
Tuesday, October 28, 2014 at 4:26pm

chemistry
Calculate the volume of 0.102M NaOH necessary to react with 22.00mL of 0.10M HCl.
Tuesday, October 28, 2014 at 4:26pm

Chemistry
the solubility of aluminum sulfate in water at 20 degrees celcius is 26.7 g/100mL Calculate the molarity?
Tuesday, October 28, 2014 at 4:14pm

chemistry
A titration of 15.75mL HCL of an unknown molarity requires 20.35mL of 0.0903M NaOH solution. What is the molarity of the HCl solution?
Tuesday, October 28, 2014 at 3:53pm

chemistry
A student adds 25.00mL of distilled water to a 10.00mL sample of HCl of an unknown molarity and titrates this against a 0.085M NaOH solution. Will the addition of the water interfere with the determination of the molarity of the HCl sample? Why or why not?
Tuesday, October 28, 2014 at 3:52pm

Chemistry
Calculate the molarity of the HCl solution if 25.00ml of the acid are required to neutralize 1.00g of each of the following 1) KOH 2)Ca(OH)2 I calculated the molar mass of KOH which was 56.11 Then I took 1.00g/56.11 = 0.0178mol To find out the molarity I did 0.0178/0.025=0....
Tuesday, October 28, 2014 at 3:36pm

Chemistry
What are the products for KMnO4 + FeSO4 + NaOH? What is the net ionic equation? I am pretty sure one of the products in MnO2, because I got a muddy brown parcipitate, but I've been getting a variety of answers.
Tuesday, October 28, 2014 at 2:15pm

Chemistry
The density of ethanol is 0.789g/cm3 at 20 degreesC. What volume of ethanol has a mass of 15.5 grams?
Tuesday, October 28, 2014 at 1:57pm

chemistry
When a 3.10g sample of liquid octane (C8H18) is burned in a bomb calorimeter, the temperature of the calorimeter rises by 26.8∘C. The heat capacity of the calorimeter, measured in a separate experiment, is 6.30kJ/∘C . Determine ΔErxn for the combustion of ...
Tuesday, October 28, 2014 at 12:47pm

chemistry
A ballon is filled with 54.8 g of CO2. The gas is at STP. Calculate the volume of the CO2 gas in liters?
Tuesday, October 28, 2014 at 12:18pm

Chemistry
Q1. A 0.5 g mixture of Cu2O and CuO contain 0.425 g Cu. What is the mass of CuO in the mixture? Q2. A chemist wants to prepare 0.5 M HCl. The label of a commercial hydrochloric acid shows that S.G. =1.18 and concentration of HCl was 37%. Calculate the volume of commercial ...
Tuesday, October 28, 2014 at 11:20am

Chemistry
The reaction of iron and water vapor results in an equilibrium reaction, 3 Fe(s) + 4 H2O(g) ¡ê Fe3O4(s) + 4 H2(g) and an equilibrium constant of 4.6 at 850¡ÆC. What is the concentration of Hydrogen present at equilibrium if the reaction is initiated ...
Tuesday, October 28, 2014 at 2:28am

AP Chemistry
if the energy to break bonds is greater than the energy to form the bonds, is it exothermic?
Tuesday, October 28, 2014 at 1:39am

Chemistry lab
based on the qualitative organic analysis 1. Why is it important to have clean test tubes before running a test? Before which tests should acetone not be used to clean the test tubes? 2. Why run solubility tests before running the functional group classification tests? ...
Monday, October 27, 2014 at 11:46pm

Chemistry
Ammonia, NH3, reacts with Phosphoric acid to produce Ammonium hydrogenphosphate, (NH4)2HPO4. What mass (in grams) of ammonia will react with 2.800E3 kg of Phosphoric acid?
Monday, October 27, 2014 at 10:38pm

chemistry
Use the molar mass of the following in order to calculate the number of moles from the given masses. Watch the significant figures a) 0.025 g of oxygen b)0.657 g og copper c) 0.7 g of chlorine I know how to calculate with finding the molar mass but not this way. thank you so ...
Monday, October 27, 2014 at 10:25pm

Organic Chemistry
In lab, we purified acetanilide through recrystallization. We did not have have time to test the melting point to check the purification, so we put the recovered crystals in a 50ml beaker, covered the top with parafilm with a few holes poked in the top, and left them for the ...
Monday, October 27, 2014 at 10:22pm

Science 10
Need examples of food for Chemistry Reactions 1. Synthesis 2. Decomposition 3.Single Replacement 3. Double Replacement So for synthesis ( A + B --> AB ) I did, Macaroni + Cheese --> Mac n Cheese For Decomposition ( AB --> A + B ) I did, Dough --> Wheat + Water ...
Monday, October 27, 2014 at 8:49pm

chemistry
The balanced equation is shown below. 2 HCl(aq) +CaCO3(s)=CaCl2(aq) +H2O(l) +CO2(g) 2.00 dm3 of a 3.00 M hydrochloric acid solution is added to the kettle (this is an excess). During the reaction 1.20 dm3 of CO2 is produced (assume 250C and 1 atmosphere) How many moles of CO2 ...
Monday, October 27, 2014 at 6:39pm

chemistry
Is this correct? 3.84 mol(2 H2O/7.68)????
Monday, October 27, 2014 at 6:36pm

chemistry
Find the mass of water (H2O) needed to react with 150 grams of potassium (K) 2K(s) + 2 H2O (g)-2KOH +H2(g) How do I get the number of moles in H2O? Desperate to understand this. I got K= 150g./39.0983=3.84 mols of K. Then would it be 3.84(2mols H2O/7.68) How do I get the ...
Monday, October 27, 2014 at 6:20pm

Chemistry
Find the mass of water (H2O) needed to react with 150 grams of potassium (K) 2K(s) + 2 H2O (g)-2KOH +H2(g) How do I get the number of moles in H2O? Desperate to understand this. I got K= 150g./39.0983=3.84 mols of K. Then would it be 3.84(2mols H2O/7.68) How do I get the ...
Monday, October 27, 2014 at 5:51pm

chemistry
Find the mass of water (H2O) needed to react with 150 grams of potassium (K) 2K(s) + 2 H2O (g)-2KOH +H2(g) How do I get the number of moles in H2O?
Monday, October 27, 2014 at 5:34pm

Chemistry
A 10.0 gram sample of a mixture of CH4 and C2H4 reacts with oxygen at 25°C and 1 atm to product carbon dioxide gas and liquid water. If the reaction produces 520 kJ of heat, what is the mass percentage of CH4 in the mixture? I am all out of tries on the homework, but I ...
Monday, October 27, 2014 at 4:56pm

chemistry
find the mass of water(H2O) needed to react with 150 grams of potassium(K)
Monday, October 27, 2014 at 4:45pm

Chemistry
I have 3 Fe (s) + 4 (H2O) (g) reacts with FeO4 (s) + 4 H2 (g) How many g of steam and iron must react to produce 375 g of magnetic oxide Fe3O4 ? I need help trying to figure out how to write the equation please
Monday, October 27, 2014 at 4:04pm

chemistry
1/10^-8 in scientific notation
Monday, October 27, 2014 at 3:34pm

chemistry
1/10^-8 in scientific notation. I need help please.
Monday, October 27, 2014 at 3:21pm

chemistry
1/0.000015 in scientific notation. Please explain how to do this.
Monday, October 27, 2014 at 3:11pm

Chemistry
1/10e-8 in scientific notation. How do I solve this please.
Monday, October 27, 2014 at 2:59pm

Chemistry
If 525J of energy are added to a 75.5g piece of iron at 22.2 degrees celcius what is the final temperature?
Monday, October 27, 2014 at 1:33pm

Chemistry
How much energy is required to raise the temperature of a 34.4g Al bar from 20.0 to 35.5 degrees celcius?
Monday, October 27, 2014 at 1:13pm

Chemistry
How many atoms of nitrogen are in 3.00g of N2O5?
Monday, October 27, 2014 at 12:34pm

chemistry phyics HELP PLEASE STUCK
A 20.0 L tank contains helium at a pressure of 100 atm and a temperature of 30 degrees Celsius. A) what is the mass of the helium inside the tank?(HINT: the molar mas of He is 4.0 g/mol B) what would the mass of nitrogen (N2) be under the same conditions?
Monday, October 27, 2014 at 3:19am

Chemistry
how to multiply 2.45 mol x 6.02x10^23
Sunday, October 26, 2014 at 10:42pm

Chemistry
1kpa to mmhg
Sunday, October 26, 2014 at 10:08pm

Chemistry
explain how to 1kpa to atm
Sunday, October 26, 2014 at 10:07pm

Chemistry
explain how to convert 814.510 torr to atm
Sunday, October 26, 2014 at 9:27pm

chemistry
To identify a diatomic gas (X2), a researcher carried out the following experiment: She weighed an empty 3.4-L bulb, then filled it with the gas at 1.40atm and 25.0 ∘C and weighed it again. The difference in mass was 5.5g . Identify the gas.
Sunday, October 26, 2014 at 9:21pm

chemistry
Predict the number of atoms of each element that would be needed to form a molecule of cadmium sulfide?
Sunday, October 26, 2014 at 8:35pm

chemistry
A molecule of sodium nitride would control how many sodium ions? Why?
Sunday, October 26, 2014 at 8:33pm

Chemistry
In the combustion of natural gas according to the equation CH4 + 2 O2 -> CO2 +2 H20, how many grams of water are formed during the combustion of 0.264 mole of CH4?
Sunday, October 26, 2014 at 8:31pm

Chemistry
what mass of precipitate will form if 1.5L of concentrated pb(clo3)2 is mixed with .55L of.190 M NaI
Sunday, October 26, 2014 at 8:31pm

Chemistry
convert 58.8 atm to kPa
Sunday, October 26, 2014 at 8:31pm

Chemistry
A student weights 1.700 g of succinic acid and dissolves it in water in a 250.0 mL volumetric flask. A 25.00 mL sample of this solution is withdrawn and placed in a 125 mL Erlenmeyer flask, to which 5 drops of the acid-base indicator phenolphthalein is added. This solution is ...
Sunday, October 26, 2014 at 8:31pm

chemistry
Li+Cl=>LiCl ionic bonding atoms valence electrons electron transfer from/ to each atom and ions formed in the product??
Sunday, October 26, 2014 at 8:28pm

Chemistry
define pressure how many mm Hg are in 875.1kPa
Sunday, October 26, 2014 at 7:57pm

General Chemistry
If the pressure is 748 mmHg, and if h= 35mm, what is the pressure of the gas, expressed in atm, If the substance in the tube is oil having a density of 0.788 g/mL? The density of mercury is 13.6 g/mL.
Sunday, October 26, 2014 at 6:13pm

Chemistry
Element X consists of two major isotopes with the following percent abundances and atomic masses: 35.0% and 85.0 amu; and 65.0% and 84.0 amu. Calculate the average atomic mass of element X.
Sunday, October 26, 2014 at 6:11pm

chemistry
which unit is used to express the pressure of gas?
Sunday, October 26, 2014 at 5:57pm

Chemistry
A 10.0 gram sample of a mixture of CH4 and C2H4 reacts with oxygen at 25°C and 1 atm to product carbon dioxide gas and liquid water. If the reaction produces 520 kJ of heat, what is the mass percentage of CH4 in the mixture? PLEASE HELP! I do not know where to even start!
Sunday, October 26, 2014 at 5:36pm

Chemistry
Calculate the molarity of the H3PO4 solution?This the question Answer has to be: MH3PO4 = ? mol/L but I don't know how to calculate it. Thanks for help so far
Sunday, October 26, 2014 at 5:18pm

CHEMISTRY
As you may well know, placing metal objects inside a microwave oven can generate sparks. Two of your friends are arguing over the cause of the sparking, with one stating that the microwaves "herd" electrons into "pointy" areas of the metal object, from ...
Sunday, October 26, 2014 at 4:52pm

General Chemistry
We mix 112 grams of oxygen gas with 118 grams of argon gas in a volume of 1752 mL at 74 degrees celsius. What will be the final pressure of the gas mixture? First, I converted the grams into moles. 112g O2 * (1mol O2/ 32g O2) = 3.5 moles O2 118g Ar * (1mol Ar/ 40g Ar) = 2.95 ...
Sunday, October 26, 2014 at 4:45pm

chemistry
2.) If you pass 10.0mL of a 50.0mL solution of [Co(en)2Cl2]Cl that has been reduced with Zn through a cation exchange column, you will obtain a solution that has three H+ ions for every Co3+ ion that was originally present in the sample. These H+ ions are titrated with 0.10-M ...
Sunday, October 26, 2014 at 3:08pm

chemistry
If you pass 10.0mL of a 50.0mL solution of [Co(en)2Cl2]Cl that has been reduced with Zn through a cation exchange column, you will obtain a solution that has three H+ ions for every Co3+ ion that was originally present in the sample. These H+ ions are titrated with 0.10-M NaOH...
Sunday, October 26, 2014 at 3:08pm

chemistry
2.) If you pass 10.0mL of a 50.0mL solution of [Co(en)2Cl2]Cl that has been reduced with Zn through a cation exchange column, you will obtain a solution that has three H+ ions for every Co3+ ion that was originally present in the sample. These H+ ions are titrated with 0.10-M ...
Sunday, October 26, 2014 at 3:07pm

chemistry
2.) If you pass 10.0mL of a 50.0mL solution of [Co(en)2Cl2]Cl that has been reduced with Zn through a cation exchange column, you will obtain a solution that has three H+ ions for every Co3+ ion that was originally present in the sample. These H+ ions are titrated with 0.10-M ...
Sunday, October 26, 2014 at 3:07pm

chemistry
If you pass 10.0mL of a 50.0mL solution of [Co(en)2Cl2]Cl that has been reduced with Zn through a cation exchange column, you will obtain a solution that has three H+ ions for every Co3+ ion that was originally present in the sample. These H+ ions are titrated with 0.10-M ...
Sunday, October 26, 2014 at 3:05pm

chemistry
If you pass 10.0mL of a 50.0mL solution of [Co(en)2Cl2]Cl that has been reduced with Zn through a cation exchange column, you will obtain a solution that has three H+ ions for every Co3+ ion that was originally present in the sample. These H+ ions are titrated with 0.10-M ...
Sunday, October 26, 2014 at 3:04pm

chemistry
2.) If you pass 10.0mL of a 50.0mL solution of [Co(en)2Cl2]Cl that has been reduced with Zn through a cation exchange column, you will obtain a solution that has three H+ ions for every Co3+ ion that was originally present in the sample. These H+ ions are titrated with 0.10-M ...
Sunday, October 26, 2014 at 3:02pm

Chemistry
The combustion of propane and oxygen produces carbon dioxide and water. What mass of water is produced from the combustion of 10.4g of propane, C3H8
Sunday, October 26, 2014 at 2:34pm

chemistry
A 100 L flask contains a mixture of methane and argon gasses at 25 degree C . The mass of argon present is 228 g and the mole fraction of methane in the mixture is 0.650 . calculate the total kinetic energy of gaseous mixture
Sunday, October 26, 2014 at 2:07pm

Chemistry
Calculate the mass in grams of the undiluted bleach that was in the sample of bleach titrated. Given: Density of undiluted bleach unkown is 1.042 g/mL. 14.44 mL of .100 M Na2S2O3. .0537 grams of NaClO. Each sample should conain 1/5 of the original undiluted bleach. Since 5mL ...
Sunday, October 26, 2014 at 1:08pm

Chemistry
In a constant-pressure calorimeter, 60.0 mL of 0.310 M Ba(OH)2 was added to 60.0 mL of 0.620 M HCl. The reaction caused the temperature of the solution to rise from 22.19 °C to 26.41 °C. If the solution has the same density and specific heat as water, what is ΔH ...
Sunday, October 26, 2014 at 12:44pm

chemistry
A compressed gas cylinder contains 1.00 into 1000 g argon gas . the pressure inside the cylinder is 2050 psi at a temp of 18 degree . how much gas remains in the cylinder if the pressure is decreased to 650 psi at a temperature of 26 degree of 26 degree c
Sunday, October 26, 2014 at 11:01am

Chemistry
Find the enthalpy change of the following reactions 2C+2H2O---> CO2+CH4 Using the following reactions with their change in H values. C+H2O---->CO+H2 H=+131.1kjmol-1 Co+H2O---->CO2+H2. H=-41.2kjmol-1 CH4+H2O--->CO+3H2 H=15.3
Sunday, October 26, 2014 at 10:47am

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