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January 26, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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chemistry
A sample of nitrogen gas is confined in a 8.278 x 10-2 L container at 2.236 x 102 torr and 50 oC. How many moles of gas are present in the sample?
Monday, January 27, 2014 at 9:21pm

Chemistry
Trichloroethane, C2H3Cl3, is the active ingredient in aerosols that claim to stain-proof men's ties. Trichloroethane has a vapor pressure of 100.0 mm Hg at 20.0 C and boils at 74.1 C. An uncovered cup (1/2 pint) of trichloroethane (d=1.325 g/mL) is kept in an 18-ft3 ...
Monday, January 27, 2014 at 9:13pm

CHEMISTRY URGENT!!!!
An electron transition in a single H-atom from n=3 to n=2 results in the release of a single photon. What is the wavelength of this photon in nanometers? NEED ANSWER CUZ MINE ISNT WORKING
Monday, January 27, 2014 at 8:27pm

chemistry
if a coin with 3.0 cm diameter, 0.2 cm thickness weighs 10.377g, what are its volume and density?
Monday, January 27, 2014 at 8:25pm

Chemistry
I need help with naming two complex ions 1) [Fe(H2O)4C2O4]+ 2)[Fe(C2O4)3]3-
Monday, January 27, 2014 at 7:09pm

Chemistry
An electron transition in a single H-atom from n=3 to n=2 results in the release of a single photon. What is the wavelength of this photon in nanometers? How do I solve this?
Monday, January 27, 2014 at 7:06pm

Chemistry
1.A patient needs 2.10×10−2g of a sulfa drug. There are 8.00mg tablets in stock. How many tablets should be given? Really need help with this! :/ Thanks -MC
Monday, January 27, 2014 at 5:54pm

Chemistry
Given the reactant side of the total ionic equation for the neutralization reaction of ammonium hydroxide (NH4OH) with hydrochloric acid (HCl), write the total ionic equation (also known as the complete ionic equation) by entering both the reactant and the product species, ...
Monday, January 27, 2014 at 4:09pm

chemistry
why is it that protonated pyrone have a higher pKa than protonated acetone?
Monday, January 27, 2014 at 9:52am

chemistry
what is the freezing point depression of water, benzene, acetic acid, ethanol and clyclohexane?
Monday, January 27, 2014 at 7:19am

organic chemistry
why is it that protonated pyrone have a higher pKa than protonated acetone?
Monday, January 27, 2014 at 12:49am

Chemistry
Assume that the complete combustion of one mole of ethanol to carbon dioxide and water liberates 1370 kJ/mol (?G°\' = –1370 kJ/mol). If the energy generated by the combustion of ethanol is entirely converted to the synthesis of a hypothetical compound X, calculate...
Monday, January 27, 2014 at 12:46am

Chemistry
Water is composed of 11.2% hydrogen and 88.8% oxygen. what mass of water contains 50.0g of 0xygen?
Monday, January 27, 2014 at 12:13am

Chemistry
How much heat energy, in kilojoules, is required to convert 63.0g of ice at −18.0 ∘C to water at 25.0 ∘C ?
Sunday, January 26, 2014 at 11:23pm

chemistry
1. An 887.0 mg sample of a mixture containing only NaCl and KCl is dissolved in water, and excess AgNO3 is added to yield 1.913 g of AgCl. Compute the mass-% of each compound in the mixture.
Sunday, January 26, 2014 at 11:21pm

chemistry
which weighs more a 101cm ^3 of copper or 92.0cm^3 of iron show work
Sunday, January 26, 2014 at 10:47pm

Chemistry
A 1.250 g mass of standard aspirin is dissolved in approximately 20 mL of 1 M NaOH. This solution is added to a 250-mL volumetric flask and diluted to the mark with DI water. How many grams per mL of aspirin are in the resulting solution? (Note that a 250-mL volumetric flask ...
Sunday, January 26, 2014 at 8:39pm

chemistry
An unknown substance has a mass of 28.1 g. The temperature of the substance increases by 16.3 degrees Celsius when 176 J of heat is added to the substance. What is the most likely identity of the substance? The table lists the specific heat capacities of select substances.
Sunday, January 26, 2014 at 7:56pm

Chemistry - Posted for Rudy
Posted by Rudy on Sunday, January 26, 2014 at 7:24pm. Hydroxylapatite, Ca10(PO4)6(OH)2, has a solubility constant of Ksp = 2.34 × 10-59, and dissociates according to Ca10(PO4)6(OH)2(s) --> 10Ca2+(aq) + 6PO43-(aq) + 2OH-(aq) Solid hydroxylapatite is dissolved in water ...
Sunday, January 26, 2014 at 7:32pm

Chemistry
Assuming that gasoline is pure octane (d = 0.703 g/mL), how many metric tons of CO2 are released in a year by an SUV that gets 19 mpg and is driven 17500. miles?
Sunday, January 26, 2014 at 5:27pm

Chemistry
what would be a possible reason for the melting point of a purified sample to be the same as the literature value in a synthesis of salicyclic acid lab??
Sunday, January 26, 2014 at 4:44pm

chemistry
A patient receives 2900mL mL of an IV {\rm IV} solution containing 1g g of glucose per 100 mL. How much energy, in kilojoules, does the patient obtain from glucose, a carbohydrate?
Sunday, January 26, 2014 at 4:04pm

chemistry
a gas has a volume of 95 mL at a pressure of 930 torr. What volume will the gas occupy at standard temperature if pressure is held constant?
Sunday, January 26, 2014 at 3:48pm

Chemistry
Consider the reaction A+B->C+3D. A solution was prepared by mixing 50 ml of .001 M of A, 100 ml of .002 M of B, 10 ml of 1 M of C, and 75 ml of .0015 M of D. At equilibrium, the concentration of D was measured and found to be .0006 M. Calculate the equilibrium ...
Sunday, January 26, 2014 at 3:10pm

Chemistry
Consider 51.5 mL of a solution of weak acid HA (Ka = 1.00 10-6), which has a pH of 4.210. What volume of water must be added to make the pH = 5.000 I've tried everything but I am not getting the right answer!
Sunday, January 26, 2014 at 1:36pm

chemistry
if you dissolve 20mg of alcl3 into 2.0 of a 2.5 molal nacl solution (density 1.08kg/l), what would be the mass concentration (ppm(weight)) of al3+ in the resulting solution?
Sunday, January 26, 2014 at 1:10pm

Chemistry
If each balloon is filled with carbon dioxide at 20 deg. C and 1 atmosphere, calculate the mass and the number of moles of carbon dioxide in each balloon at maximum inflation.
Sunday, January 26, 2014 at 1:02pm

analytical chemistry
at elevated temperature, NaHCO3 (83.98g/mol) is converted quantitatively to Na2CO3 (105.98g/mol).Ignition of 0.3592g sample of an antacid tablet containing NaHCO3 and non volatile impurities yielded a residue weighing 0.2362g. Calculate the percent purity of the sample.
Sunday, January 26, 2014 at 7:17am

chemistry
calculate the expansion work done when 50 g of water is electrolyzed under constant pressure at 25 c...why i get 6.8kj
Sunday, January 26, 2014 at 6:25am

Chemistry
When a 3.00-g sample of KCN is dissolved in water in a calorimeter that has a total heat capacity of 1.123 kJ·K–1, the temperature decreases by 0.480 K. Calculate the molar heat of solution of KCN.
Sunday, January 26, 2014 at 12:02am

chemistry
Say you have two substances, A and B. A has a melting point of 300 degrees Celcius, while B has a melting point of 200 degrees Celcius. If you took a mixed melting point where the ratio of A is higher than B, what would the melting range look like? Would the melting point be ...
Saturday, January 25, 2014 at 8:45pm

Chemistry
Air Pollution: How do I use equations to describe the question "How is it formed?' for the air pollution?
Saturday, January 25, 2014 at 7:19pm

organi chemistry
Calicheamicin is an antitumor compound produced by a microorganism isolated in Texas soil. Below is the enediyne core of calicheamicin, which is responsible for its antitumor activity. (a) Mark the hybridization state of each carbon. Ignore the –R groups. (b) What are the...
Saturday, January 25, 2014 at 12:17pm

Chemistry
The gas phase decomposition of dinitrogen pentoxide at 335 K N2O5(g) 2 NO2(g) + ½ O2(g) is first order in N2O5. During one experiment it was found that when the initial concentration of N2O5 was 0.218 M, the concentration of N2O5 dropped to 2.96E-2 M after 282 s had ...
Friday, January 24, 2014 at 9:35pm

AP Chemistry
A 0.00100 M solution of a weak acid HX is 6% ionized. Calculate Ka for the acid.
Friday, January 24, 2014 at 8:14pm

AP Chemistry
A given weak acid HZ has a Ka=1.7×10−6. What is the H3O+ concentration of a solution of HZ that has a concentration of 0.78 mol/L? What is the pH of this solution of HZ? What is the percent ionization of HZ in this solution? Answer in units of %
Friday, January 24, 2014 at 6:21pm

AP Chemistry
What is the pH of a 0.41 M solution of pyridinium chloride (C5H5NH+Cl−)? (Kb for pyridine is 1.5×10−9.) Answer in units of pH
Friday, January 24, 2014 at 6:18pm

AP Chemistry
Consider the ionization constants cyanic acid (HOCN) : Ka= 3.5×10−4; ammonia (NH3): Kb= 1.8×10−5. A solution of ammonium cyanate (NH4OCN) is 1. acidic, because the cation and the anion hydrolyze to the same extent. 2. acidic, because the anion ...
Friday, January 24, 2014 at 6:12pm

Chemistry
The half-life of 131I is 8.021 days. What fraction of a sample of 131I remains after 24.063 days? 1/2 1/4 1/8 1/16 Please help. Thank you
Friday, January 24, 2014 at 6:03pm

AP Chemistry
Like all equilibrium constants, Kw varies somewhat with temperature. Given that Kw is 7.51×10−13 at some temperature, compute the pH of a neutral aqueous solution at that temperature.
Friday, January 24, 2014 at 5:53pm

chemistry
What is the concentration of a solution, in gsolute/100gsolvent, made using 2.29 g of KNO3 in 2.03 g of H2O?
Friday, January 24, 2014 at 4:02pm

Chemistry 1
Imagine that a hypothetical life form is discovered on our moon and transported to Earth. On a hot day, this life form begins to sweat, and it is determined that the heat of vaporization of its sweat is 215 cal/g. The scientist observing the extraterrestrial life form also ...
Friday, January 24, 2014 at 1:06pm

Chemistry
A student obtained a clean, dry glass- stoppered flask. She weighed the flask and stopper on an analytical balance and found the total mass to be 33.695 g. She then filled the flask with water and obtained a mass for the full stoppered flask of 64.356 g. From these data, and ...
Friday, January 24, 2014 at 11:05am

chemistry
You are analyzing a solid isolated from a reaction and find that its boiling point is over 1000 ∘C. You dissolve the compound in water solution and recrystallize it to produce some solid crystals that you use to determine that the compound is a crystalline solid. Which ...
Thursday, January 23, 2014 at 7:52pm

Chemistry
For the gas phase decomposition of chloroethane, CH3CH2Cl C2H4 + HCl the rate constant at 723 K is 1.75E-4 /s and the rate constant at 769 K is 2.19E-3 /s. The activation energy for the gas phase decomposition of chloroethane is
Thursday, January 23, 2014 at 7:16pm

chemistry
in a freezer, 150g of water at 0degrees celcius is placed in an ice cube tray. how much energy, in kilocalories, must be removed to form ice cubes at 0 degrees celsius
Thursday, January 23, 2014 at 3:32pm

chemistry
While you are at rest your brain gets 15% by volume of your blood. If your body contains 5.2 L of blood, how many liters of blood are in your brain at rest? and how many quarts?
Thursday, January 23, 2014 at 12:21pm

chemistry
How many grams of H2O (Mm = 18.0 g/mol) are produced in the combustion of 70.0 g of C4H10 (Mm = 58.1 g/mol)? 2C4H10 + 13O2 8CO2 + 10H2O
Thursday, January 23, 2014 at 12:10pm

Chemistry
Calculate the heat given off when 177 g of copper cools from 155.0 c to 22.0 c. The specific heat capacity of copper is 0.385 j/g c
Thursday, January 23, 2014 at 11:43am

Chemistry II
Determine the grams of solute required to prepare 0.5 m solution HC2H3O containing 750 g of water. Make sure to show your work. **(Thanks for helping by the way.)**
Wednesday, January 22, 2014 at 10:21pm

Chemistry - Thermodynamics
A piece of metal of mass 12 g at 104◦C is placed in a calorimeter containing 45.4 g of water at 22◦C. The final temperature of the mixture is 71.5 ◦C. What is the specific heat capacity of the metal? Assume that there is no energy lost to the ...
Wednesday, January 22, 2014 at 9:02pm

chemistry
What will be the average density for a sample of metal with a mass of 12.6 g and volume calculations of 7.8 mL and 8.3 cm3 ? Omit units in the answer and report answer to one decimal place.
Wednesday, January 22, 2014 at 7:12pm

chemistry
What will be the average density for a sample of metal with a mass of 12.6 g and volume calculations of 7.8 mL and 8.3 cm3 ? Omit units in the answer and report answer to one decimal place.
Wednesday, January 22, 2014 at 7:11pm

chemistry
The rate constant,K, for a given was determined at a number of temperatures. A graph of log K versus the reciprocal of the kelvin temperature yielded a straight line with a slope of -250 K. What is the activation energy of this reaction in Kj/mol? For this question I got 2....
Wednesday, January 22, 2014 at 3:59pm

Chemistry
Balance KCLO3 ---> KCl + O2
Wednesday, January 22, 2014 at 3:37pm

Chemistry
1. How do you that these react? If they do, what are the products? How do you do this? i.) F^- + Br2----> ii.) Br^- + Cl2-----> 2. Explain why boiling point increases from S to Se to Te.... 3. What is the electron configuration and arrangement of Fe^3+? How is this ...
Wednesday, January 22, 2014 at 1:09am

AP Chemistry
The pH of a solution of hydrochloric acid is 1.67. What is the molarity of the acid? Answer in units of mol/L
Tuesday, January 21, 2014 at 6:44pm

Chemistry Help Please!
An industrial chemist puts 1.00 mol each of H2(g) and CO2(g) in a 1.00-L container at 800oC. When equilibrium is established, 0.49 mol of CO(g) is in the container. Find Kc at 800 C for the following reaction: H2(g) + CO2(g) ⇌ H2O(g) + CO(g).
Tuesday, January 21, 2014 at 2:50pm

Chemistry Help Please!
SHOW WORK PLEASE SO I CAN DO THE REST OF MY HW BY LOOKING AT THIS QUESTION. The decomposition of hydrogen peroxide is catalyzed by iodide ion. The catalyzed reaction is thought to proceed by a two-step mechanism: 1. H2O2(aq) + I(aq) → H2O(l) + IO(aq) (slow)  &#...
Tuesday, January 21, 2014 at 2:01pm

Chemistry
Write chemical formula (complete with reactants), balance. ammonium sulfide + aluminum phosphate
Tuesday, January 21, 2014 at 4:55am

Chemistry
To neutralize a 0.5192 g organic acid, 44.0 mL NaOH solution (1.00 ml ~ 1.12 mL HCl ~ 0.0100 g CaCO3) is required. What is the equivalent weight of the organic acid?
Tuesday, January 21, 2014 at 4:17am

Chemistry
What will be the volume of concentrated H2SO4 that must be added to 155 mL of 0.1996 N H2SO4 in a 500 mL volumetric flask so that the resulting solution will be 6.5210 M? pls. explain.
Tuesday, January 21, 2014 at 4:07am

Chemistry
Over the years, the thermite reaction has been used for welding railroad rails, in incendiary bombs, and to ignite solid-fuel rocket motors. The reaction is the following. Cr2O3(s) + 2 Al(s) → 2 Cr(l) + Al2O3(s) What masses of chromium(III) oxide and aluminum must be ...
Tuesday, January 21, 2014 at 3:26am

Chemistry
Calculate the volume of 2.503 N HNO3 added to 100 mL of HCl in order to prepare 1.1251 N acid solution from the following data: 58.96 mL NaOH will neutralize 2.521g of potassium tetroxalate and 45.57 mL of HCl will neutralize 53.0 mL of the NaOH solution.
Tuesday, January 21, 2014 at 3:11am

chemistry
A mixture containing 50grams of carbon and 75 grams of oxygen is sealed in a flask. The total mass of the system is 225 grams. The flask is heated to cause the carbon and oxygen to react. The sealed flask is massed. What is the mass of the sealed flask? A) 125 grams B) 150 ...
Monday, January 20, 2014 at 8:29pm

chemistry
Which 2 types of steel appeared to have their properties combined in tempered steel
Monday, January 20, 2014 at 6:09pm

Chemistry
A sample of nitrogen gas is confined in a 8.494 L container at 2.643 x 102 torr and 50 oC. How many moles of gas are present in the sample? So I thought I set this problem up right and when I type the answer into CALM my answer is incorrect. This is what I did: PV=nRT (2.643 x...
Monday, January 20, 2014 at 4:50pm

chemistry
Diagram for the preparation of oxygen from potassium trioxochloric(v)
Monday, January 20, 2014 at 2:24pm

Chemistry
For example, when a question asks about two equivalents of bromine, does that mean Br2 OR 2Br2? Thanks
Monday, January 20, 2014 at 2:18pm

Chemistry
Calculate the % Na2CO3 and % BaCO3 in a 0.2005g sample which requires 28.0mL of 0.9990 N acid for complete neutralization.
Monday, January 20, 2014 at 2:36am

Chemistry
To what volume must 1580mL of 0.2005 N solution be diluted so that the resulting solution will be 0.1899 M? How much water will be needed in the dilution?
Monday, January 20, 2014 at 2:33am

Chemistry
I have been researching, but I find no reliable sources. I want to check with you if these are true.... Are we actually not touching the ground due to the repulsion of the electron clouds between our feet and the ground? Same with the clothes we wear and our body?? Are we not ...
Monday, January 20, 2014 at 12:51am

Chemistry
What is molecular mass of CuSO4(NH4)SO4.H2O
Sunday, January 19, 2014 at 11:01pm

AP Chemistry
What is the mass percent of acetic acid in 3.25 molality of CH3COOH?
Sunday, January 19, 2014 at 10:10pm

chemistry
In a combustion reaction, propane (C3H8) reacts with oxygen. How many moles of CO2 can be produced when 2.25 mol of C3H8 react? C3H8(g) + 5O2(g) -„³ƒn3CO2(g) + 4H2O(g)
Sunday, January 19, 2014 at 7:24pm

Chemistry
Calculate the pH of the solution formed by adding 15.0ml of 0.1M sodium hydroxide to 30.0ml of 0.1M propanoic acid.
Sunday, January 19, 2014 at 6:33pm

AP Chemistry
Why would .25 molality of CaCl2 have a larger effect on the freezing point of water than .25 molality of NaCl?
Sunday, January 19, 2014 at 5:50pm

Chemistry
A 0.2299 N acid is prepared by mixing 100 ml of 0.1234 N H2SO4 and 0.3200 N HCl. How much HCl is needed in the preparation of the solution?
Sunday, January 19, 2014 at 2:14am

chemistry who helps me for me
A 0.887g sample of a mixture of nacl and kcl is dissolved in water , and the solution is then treated with an excess of agn03 to yield 1.913g of agcl. Calculate the percent by mass of nacl in the mixture 1.913/143g/mol = 0.01337 who helps me
Saturday, January 18, 2014 at 11:46pm

chemistry Who clearlyexplain step by step
1g of mixture na2c03 and k2c03 was made upto 250ml is aqueous solution. 25ml of this solution was neutralized 20ml of hcl of unknown concentration. The neutralized solution requires 16.24ml of 0.1N agn03 for precipitation Calculate A) the k2c03 is mixture b) conc of hcl in g/L...
Saturday, January 18, 2014 at 11:11pm

chemistry Who helps step by step
0.887g sample of a mixture of nacl and kcl is dissolved in water. The solution is then treated with an excess agn03 to yield 1.1930of agn03. Calculate the percent by mass of each compound in the mixture agcl = 143g/mol 1.1930/143 = 0.001337 m agcl x/58g/mol + (0.8870g -x) + y/...
Saturday, January 18, 2014 at 1:20pm

Chemistry
Calculate the volume of oxygen at 27C and 740 mmHg which could be obtained by hesting 10g of potassium trioxochlorate (v)
Saturday, January 18, 2014 at 9:30am

chemistry
In a reaction A to products, ,4.40 min after the reaction is started concentration of A is 0.588M. The rate of reaction at this point is rate= -change in concentration of A/change in time=2.2x10^-2Mmin^-1. Assume that this rate remains constant for a short period of time. A. ...
Saturday, January 18, 2014 at 2:07am

Chemistry
Is esterification a condensation reaction?
Saturday, January 18, 2014 at 1:04am

Chemistry
Is esterification a condensation reaction?
Saturday, January 18, 2014 at 1:04am

Chemistry
Which gas diffuses most rapidly at STP? Ar, Kr, N2, or O2? Why?
Friday, January 17, 2014 at 9:39pm

Chemistry
Hey can anyone help me solve these questions 1. Balance K2Cr2O7 +H2C2O42H2O --> K[Cr(CrC2O4)2(H2O)2]2H2O +CO2+ H2O 2. Calculate the theoretical yield of the reaction mentioned above 3.What is the theoretical percentage by weight of Cr in the reaction mentioned above 4. Why ...
Friday, January 17, 2014 at 9:21pm

Chemistry
Which of the following must be the same before and after a chemical reaction? Answer: The sum of the masses of all substances involved and the number of atoms of each type involved. WHY?
Friday, January 17, 2014 at 3:06pm

Chemistry
Assume a baker of pure water has been boiling for 30 minutes. What is in the bubbles in the boiling water? Answer: water vapor. WHY?
Friday, January 17, 2014 at 3:05pm

Chemistry
Heat is given off when hydrogen burns in air according to the equation: 2H2 + O2 ---> 2H2) What is responsible for the heat? I know the answer is froming hydrogen-oxygen bonds gives off energy, but why?
Friday, January 17, 2014 at 3:00pm

Chemistry
Iron combines with oxygen and water from the air to form rust. If an iron nail were allowed to rust completely, one should find that the rust weighs: I know the answer is the rust should way more than the nail it came from but can someone explain why please!
Friday, January 17, 2014 at 2:44pm

chemistry
How many moles of protons are present in 7.54 grams of Rubidium? Report your answer to 3 significant figures.
Friday, January 17, 2014 at 1:32pm

Chemistry
If you add 4.6 g of sodium to water, how many molecules of H2 will be formed? (4points) 2Na(s)+2H2O(l)-->2NaOH(aq)+H2(g)
Friday, January 17, 2014 at 11:34am

Chemistry Check Please! ?Fixed
A solution is prepared by dissolving 3.44 g of sucrose, C12H22O11, in 118 g of water. a) What is the molality of the resulting solution? b) What is the mole fraction of water in this solution? B) moles of h2o=118g/18(g/mol)=6.548 mol moles of c12h22O11= 3.44g/342.3(g/mol)=0....
Friday, January 17, 2014 at 2:52am

chemistry
how many grams of CH4 (methane) must be burned to form 82.6g of H2O? equation: CH4+O2----> CO2+H2O
Thursday, January 16, 2014 at 11:33pm

chemistry
how many grams of CH4 (methane) must be burned to form 82.6g of H2O? equation: CH4+O2----> CO2+H2O
Thursday, January 16, 2014 at 9:13pm

chemistry
A sulfuric acid solution containing 571.8gg of H2SO4 per liter of solution has a density of 1.329 g/cm3 Calculate the mole fraction of H2SO4 in this solution.
Thursday, January 16, 2014 at 5:26pm

chemistry
The best means of personal protection from radiation for emergency responders is the implementation of three basic principles: time, distance and shielding. Please show your work when answering the following questions: a. Using the inverse square law of radiation, what Geiger ...
Thursday, January 16, 2014 at 4:53pm

chemistry
A student finds a rock on the way to school. In the laboratory he determines that the volume of the rock is 29.7 cm3, and the mass in 139.943 g. What is the density of the rock?
Thursday, January 16, 2014 at 9:41am

Chemistry Check Please!
A solution is prepared by dissolving 3.44 g of sucrose, C12H22O11, in 118 g of water. a) What is the molality of the resulting solution? b) What is the mole fraction of water in this solution? B) moles of h2o=118g/18(g/mol)=6.5556 mol moles of c12h22O11= 3.44g/342.3(g/mol)=0....
Thursday, January 16, 2014 at 1:19am

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