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March 5, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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chemistry
What is ΔH in the equation ΔG = ΔH - TΔS? A. The change in specific heat between the products and the reactants B. The change in enthalpy between products and reactants in a reaction C. The change in entropy between products and reactants in a reaction D. ...
Tuesday, November 25, 2014 at 5:34pm

chemistry
What would cause entropy to increase in a reaction? A. The products forming a more rigid structure B. The products forming an ordered pattern C. The products becoming more spread out D. The products forming fewer molecules I think the answer is c or d
Tuesday, November 25, 2014 at 5:13pm

Chemistry help drbob222
Which of the following processes would result in a negative entropy change? A. Leaves falling off a tree B. A deck of cards falling on the floor C. A piece of cake crumbling as it is cut D. A student filing papers I think d
Tuesday, November 25, 2014 at 4:17pm

Chemistry
If the student collected 3.46g of acetone and the theoretical yield is 3.67 g, what is the percent yield?
Tuesday, November 25, 2014 at 3:49pm

Chemistry
How many grams of oxygen gas must react to give 2.80g of ZnO? 2Zn(s)+O2(g)→2ZnO(s)
Tuesday, November 25, 2014 at 3:47pm

Chemistry
How many grams of oxygen gas must react to give 2.80g of ZnO?
Tuesday, November 25, 2014 at 3:43pm

Chemistry
Given the molar concentration of hydroxide ion, calculate the concentration of hydrogen ion. [OH-]=0.0010 Can someone please help me with this process. Thanks
Tuesday, November 25, 2014 at 3:23pm

Chemistry
Determine the acid and base that were neutralized to produce each of the following salts. Li2CO3 (aq). I don't understand how to solve this.
Tuesday, November 25, 2014 at 2:41pm

Chemistry
If 45.5 g of calcium carbonate is reacted with phosphoric acid, how many grams of carbon dioxide will be produced if the reaction yield is 85.0 %?
Tuesday, November 25, 2014 at 2:40pm

Chemistry
Given the molar concentration of hydrogen ion, calculate the concentration of hydroxide ion [H+]=7.9*10-7
Tuesday, November 25, 2014 at 2:39pm

Please Help Me With This Chemistry HW Question!
Should 25 ml of 0.15 M HCL solution be added to 250 mL of buffer solution containing 0.25M HF Ka-7.1 x 10, and 0.40 M NaF at a pH of 3.15 what is the new pH?
Tuesday, November 25, 2014 at 2:27pm

Chemistry
How many grams of CO2 could be produced from the combustion of 0.0713 mol. of C2H4 in the presence of 0.156 mol. of O2?
Tuesday, November 25, 2014 at 2:19pm

Chemistry
Calculate how much acetylene (C2H2) can be produced from 358 g of H2O and an excess of CaC2 if the percent yield for this reaction is 94.5%. CaC2 + 2H2O -> C2H2 + Ca(OH)2
Tuesday, November 25, 2014 at 12:29pm

Chemistry
3NO2 + H2O -> 2HNO3 + NO Calculate the percent yield for the following reaction if 76.8 g of H2O reacted and 125 g of NO were produced.
Tuesday, November 25, 2014 at 12:25pm

Chemistry
68.0g of solute were dissolved in 393 mL of benzene. The solution froze at -0.50°C. The normal freezing point of benzene is 5.5°C and the molar freezing point constant is 5.12°C kg/mol. The density of benzene is .879 g/mol. Calculate the molar mass of the solute.
Tuesday, November 25, 2014 at 11:03am

Chemistry
In a routine laboratory analysis, a solution of sodium chromate with a chromium concentration of 175.0 ppm is required. Calculate the molarity of this solution.
Tuesday, November 25, 2014 at 10:59am

chemistry
how many grams of BaCl2 are present in 150 g of H20 if the concentration is 0.3 m?
Tuesday, November 25, 2014 at 10:38am

chemistry
how many moles of BaCl2 are in 300 g of H2O if the molality is 0.2 m?
Tuesday, November 25, 2014 at 10:37am

chemistry
what is the molality of 18 g NaCl in 200 g of H2O?
Tuesday, November 25, 2014 at 10:36am

chemistry
3moles KI in 500 g of H2O equals what molality?
Tuesday, November 25, 2014 at 10:35am

chemistry
how many ml of 0.5 M BaCl2 are needed to have 75 g of BaCl2?
Tuesday, November 25, 2014 at 10:34am

chemistry
what volume of 0.5 BaCl2 is needed to have 0.1 moles of BaCl2?
Tuesday, November 25, 2014 at 10:33am

chemistry
how many moles of Kl are present in 500 ml of a 0.2 M solution?
Tuesday, November 25, 2014 at 10:32am

chemistry
calculate the molarity of a g NaCl in 250 ml solution.
Tuesday, November 25, 2014 at 10:32am

chemistry
3 moles C6H12O6 in 100 ml equals what molarity?
Tuesday, November 25, 2014 at 10:31am

Chemistry
How do I balance CuSO4 + NH3 + H2O = (NH4)2SO4 + Cu(NH3)4(OH)2 Thank you!!!
Monday, November 24, 2014 at 11:32pm

chemistry 2
A certain laser uses a gas mixture consisting of 9.0 grams of Hydrogen chloride, 2.0 grams Hydrogen gas, and 165.0 grams of Neon. What pressure is exerted by the mixture in a 75.0 liter tank at 22 degree Celsius? Which gas has the smallest partial pressure?
Monday, November 24, 2014 at 10:45pm

Chemistry
In 250 mL of a 0.35 M solution of NaOH, there are how many grams of NaOH?
Monday, November 24, 2014 at 10:41pm

Chemistry
how many Kj of heat are evolved when 6g of pure carbon is completely burned? how many grams of carbon must be burned to furnish 39.3 kJ of heat. enthalpy of combustion of carbon is -393.5
Monday, November 24, 2014 at 10:40pm

Chemistry
The equilibrium constant for the reaction H2 + I2 --> 2HI, is 54 at 425 degrees C. If the equilibrium mixture contains 0.030 M HI and 0.015 M I2, calculate the equilibrium concentration of H2.
Monday, November 24, 2014 at 10:40pm

chemistry-naming
How do I name the following- C3H8? (the numbers are supposed to be subscripts) KCl?
Monday, November 24, 2014 at 9:58pm

Chemistry
What is the concentration of sodium phosphate contains 0.60 M Na+? I'm not sure what to do and how to figure how to do this question.
Monday, November 24, 2014 at 9:57pm

Chemistry
2 ml of stock antibiotic (64 mg/ml) was diluted into a test tube containing 2 ml of broth (final volume is 4). A series of 2-fold SERIAL DILUTIONS were performed by transferring 2 ml to three other tubes, consecutively (final volumes now 2 ml in each tube). The final ...
Monday, November 24, 2014 at 9:26pm

Chemistry
A sample of lithium sulfate, Li2SO4, contains 6.78 x 10^23 formula units. a) How many moles of Li+ ions are there in the sample? b) How many moles of ions are there in the sample? My work. I think a) is 2.26 is that correct?
Monday, November 24, 2014 at 7:25pm

Chemistry
Provide the name(s) for the branched constitutional isomer(s) with the molecular formula C7H16 that have three methyl groups.
Monday, November 24, 2014 at 7:00pm

Chemistry
A sample of toluene, C7H8 has a mass of 74.5 g. How many carbon atoms does it contain? How many hydrogen atoms does it contain? My work: I get 3.41 x 10^24 for carbon atoms And 3.90 x 10^24 for hydrogen atoms. Is this correct?
Monday, November 24, 2014 at 6:44pm

chemistry
What mass of AuCl3 contains 160.9 g of gold? My work i got 104.6 g is that correct
Monday, November 24, 2014 at 6:21pm

Chemistry
A sample of toluene, C7H8 has a mass of 74.5 g. a) how many molecules does the sample contain? b) How many carbon atoms does it contain? How many hydrogen atoms does it contain? My work For b would it be 7 carbon atoms and 8 hydrogen atoms
Monday, November 24, 2014 at 6:00pm

PLEASE HELP CHEMISTRY
What mass of pure silver would you obtain from 85.0 g of AgNO3? I got 53.55 g is that correct?
Monday, November 24, 2014 at 5:47pm

chemistry
I just need a definitive answer because I've searched everywhere and it's made me second guess my original answer. How many valence electrons does copper have? I thought it was one but now I'm unsure. I know it's electron configuration is [Ar]4s1 3d10, so that...
Monday, November 24, 2014 at 5:46pm

Chemistry
A sample of lithium sulfate, LiSO4, contains 6.78 x 10^23 formula units. a) How many moles of Li+ ions are there in the sample? b) How many moles of ions are there in the sample? My work: I think a) is 2.26 moles And b i am not sure
Monday, November 24, 2014 at 5:36pm

chemistry physics
A car is traveling toward you at 40.0 mi/h. The car horn produces a sound at a frequency of 480 Hz. What frequency do you hear? Assume that the sound velocity in air is 1090 ft/s. Do I need to convert ft/s to m/s?
Monday, November 24, 2014 at 5:19pm

Chemistry Physics
What frequency is heard by an observer who hears the 450 Hz siren on a police car traveling at 35 m/s away from her? Assume that the velocity of sound in air is 345 m/s. Is this the correct? 450*345/(345+35) =408Hz
Monday, November 24, 2014 at 5:10pm

Chemistry Homework Help Please!
1.) Quantify the pH for a solution prepared by dissolving 0.050 moles of Acetic Acid (CH3COOH) and 0.20 moles of Sodium Acetate (CH3COONa) in water and adjusting the volume to 500 mL. The pka for Acetic Acid (CH3COOH) is 4.75. 2.) Should 0.010 moles of NaOH be added to this ...
Monday, November 24, 2014 at 4:16pm

Chemistry
A sample of lithium sulfate, Li2SO4, contains 6.78 x 10^23 formula units a) How many moles of Li+ ions are there in the sample b) How many moles of ions are there in the sample
Monday, November 24, 2014 at 4:13pm

Chemistry
Should 25 ml of 0.15 M HCL solution be added to 250 mL of buffer solution containing 0.25M HF Ka-7.1 x 10, and 0.40 M NaF at a pH of 3.15 what is the new pH?
Monday, November 24, 2014 at 3:37pm

Chemistry Homework Help
d 25 ml of 0.15 M HCL solution be added to 250 mL of buffer solution containing 0.25M HF Ka-7.1 x 10, and 0.40 M NaF at a pH of 3.15 what is the new pH?
Monday, November 24, 2014 at 3:36pm

chemistry
If you need to multiply the following reaction by 2 to be an intermediate reaction in a Hess's law problem, what would be the final value for the enthalpy of reaction you use for this intermediate reaction? C2H4 + 3 O2 2 CO2 + 2 H2O, H = -1410 kJ
Monday, November 24, 2014 at 2:38pm

Chemistry Physics
What is the wavelength in metres of an electromagnetic wave with a frequency of 10^14/s?
Monday, November 24, 2014 at 2:23pm

Chemistry
What is the pressure in a 22.1-L cylinder filled with 16.3g of oxygen gas at a temperature of 329K?
Monday, November 24, 2014 at 2:18pm

Chemistry Physics
What is the wavelength of an electromagnetic wave with frequency 50.0 MHz? Am I starting this problem like this? 3.00*10^8/50*10^6 =6*10^12
Monday, November 24, 2014 at 2:00pm

Chemistry
Calculate the S(univ) for the following phase change at 25 deg celcius. The boiling point of heptane is 98.0 Celcius and has a Delta Hvap= +21.6kj/mol. C7H16(l)--> C7H16(g) Delta S= +79.0j/k I know that the equation is Delta Suniv= DSsys + DSsurr PLEASE SOMEONE HELP ME WITH...
Monday, November 24, 2014 at 11:38am

chemistry
0.195 m of ca oh 2 solution to neutralize 750 ML of a 0.235 m of hno3 and balance it
Monday, November 24, 2014 at 11:19am

Chemistry 211
Which of the following statements is a reasonable explanation for why a percent yield may be less than 100% for the synthesis of the alum, select all that apply. a) The aluminium foil did not completely react b) Some alum sample remained in the beaker and was not transferred ...
Monday, November 24, 2014 at 10:09am

Chemistry
For the reaction CaCO3(s)+ 2HCl(aq)= CaCl2(aq)+ CO2(g)+ H2O(l) how many grams of CaCl2 can be obtained if 14.6 g HCl is allowed in CaCO3?
Monday, November 24, 2014 at 1:47am

Chemistry
Provide the name(s) for the branched constitutional isomer(s) with the molecular formula C7H16 that have three methyl groups.
Monday, November 24, 2014 at 12:54am

Chemistry
If 35.0 mL of 0.210 M HCl reacts with excess Mg, how many mL of hydrogen gas are produced at STP? Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g) Is the answer 0.8176 L Convert moles of HCl: 2.10 x 0.035= 0.00735 mol of HCl Convert to moles of H2: 0.0735 x 1 mol H2/ 2 mols HCl= 0....
Monday, November 24, 2014 at 12:40am

Chemistry
How many mL of a stock 2.50M HCl solution are required to prepare 25.0 mL of a 0.15M HCl solution?
Sunday, November 23, 2014 at 11:14pm

Chemistry
A certain reaction has an equilibrium constant of 0.65. Calculate the constant for the reverse reaction.
Sunday, November 23, 2014 at 11:11pm

chemistry
Use the Henderson-Hasselbalch equation to calculate the pH of a solution that is 0.140M in propanoic acid and 0.120M in potassium propanoate
Sunday, November 23, 2014 at 11:03pm

Chemistry
Calculate the energy (kJ) required to raise the temperature of 22g of water from 12 C to 90 C.
Sunday, November 23, 2014 at 10:02pm

Chemistry
If 120. grams of KClO3 reacts, how many grams of oxygen are produced?
Sunday, November 23, 2014 at 8:34pm

chemistry
Calculate the vapor pressure of a solution containing 28.7g of glycerin (C3H8O3) in 136mL of water at 30.0 ∘C. The vapor pressure of pure water at this temperature is 31.8 torr. Assume that glycerin is not volatile and dissolves molecularly (i.e., it is not ionic) and ...
Sunday, November 23, 2014 at 8:32pm

Chemistry - Heat of Fusion of Ice
I need help with these questions since the lab report needs to be completed like...NOW >_< We were supposed to experimentally determine the heat of fusion of ice and compare it to the accepted value as listed in your reference table.Please help me: Does the value depend ...
Sunday, November 23, 2014 at 8:10pm

chemistry
What mass of rhodium contains as many atoms as there are zirconium atoms in 23 g of zirconium?
Sunday, November 23, 2014 at 6:45pm

Chemistry
The thermite reaction was used to weld rail ties together. If 15.0 grams of aluminum were used, how many grams of ferric oxide would be required? How many grams of molten iron would forma?
Sunday, November 23, 2014 at 6:04pm

Chemistry
Draw all of the possible alkyne isomers of CH≡CCH2CH2CH2CH3.
Sunday, November 23, 2014 at 5:10pm

Chemistry
What volume will 823 mL of SO3 gas at 11 degrees celsius and 720 mm Hg occupy when the pressure is raised to 1.55atm and the temperature is raised to 81 degrees celsius?
Sunday, November 23, 2014 at 4:28pm

chemistry
How many milliliters of 0.413 M NaC2H3O2 are needed to supply 27.3 g NaC2H3O2?
Sunday, November 23, 2014 at 4:01pm

Chemistry
An excess of Al and 7.9 Mole of Br2 are reacted according to the question 2Al+3 Br2 equals 2AlBr3
Sunday, November 23, 2014 at 3:46pm

Chemistry
What mass of AuCl3 contains 160.9 g of gold? My work i got 104.6 g Am i right?
Sunday, November 23, 2014 at 3:18pm

Chemistry
Calculate the pH of a 1.19M sodium formate, HCOONa, solution.
Sunday, November 23, 2014 at 3:17pm

Chemistry
What mass of pure silver would you obtain from 85.0 g of AgNO3? My work The answer i got is 53.55 g Am i right?
Sunday, November 23, 2014 at 3:17pm

Chemistry
Calculate the pH of a buffer solution made by mixing 231 mL of a 1.04M trimethylamine (CH3)3N solution with 176 mL of a 1.38M trimethylammonia chloride, (CH3)3NHCl solution. Enter your answer to TWO decimal places. DO NOT use scientific notation.
Sunday, November 23, 2014 at 2:18pm

chemistry
50ml of 20.8% bacl2 and 100ml of 9.8% h2s04 solutions are mixed. Molarity of cl ions in the resulting solution wt of ba =137 I do not still understand step by step clearly Thank a lot
Sunday, November 23, 2014 at 1:53pm

Chemistry
How many grams of nitric acid (HNO3) must be dissolved in 590 ml of water to make a solution with a pOH = 10.1? Select one: a. 2.9 x 10-9 g b. 7.9 x 10-3 g c. 4.7 x 10-3 g d. 7.9 x 10-6 g e. 7.4 x 10-5 g
Sunday, November 23, 2014 at 1:23pm

chemistry
I have to calculate the ΔV= final volume-initial volume For the first trial the final volume was .005mL the initial volume was .03mL, which equaled to -.025mL. The volume was negative because it was exothermic reaction. For the second trial the final volume was 0.015 and ...
Sunday, November 23, 2014 at 1:10pm

chemistry
The National Institute of Science and Technology (NIST) kinetics database lists the rate constant, k, of a particular gaseous reaction as 8.56× 10–10 cm3·molecule–1·s –1 at 298 K. convert to units of M-1 s-1. convert rate constant to units of...
Sunday, November 23, 2014 at 12:43pm

Chemistry
Calculate the S(univ) for the following phase change at 25 deg celcius. The boiling point of heptane is 98.0 Celcius and has a Delta Hvap= +21.6kj/mol. C7H16(l)--> C7H16(g) Delta S= +79.0j/k I know that the equation is Delta Suniv= DSsys + DSsurr PLEASE SHOW ME HOW TO DO IT...
Sunday, November 23, 2014 at 12:12pm

Chemistry
What is the mole fraction of O2 in a mixture of 15.1g of O2, 8.16g of N2, and 2.46g of H2? (PLEASE EXPLAIN WHAT YOU DO!) Thanks
Sunday, November 23, 2014 at 11:33am

Chemistry
How do you set up this problem? Calculate the volume , in ml of a 0.150 M NaOH soulution needed to neutralize 25.0ml of a 0.288 M HCl solution?
Sunday, November 23, 2014 at 10:46am

Chemistry
In the reaction 2A+B2 to 2AB if 0.5 moles of A and an excess of B are combined and the reaction goes to %100 completion, then how many moles of C are formed?
Sunday, November 23, 2014 at 10:10am

chemistry
2Al (s) + 3Cl2 (g)  2 AlCl3 (s) i)obtain the limiting reagent. when 2.00 mole of Cl2 (g) is reacted with 54.3 g of Al (p). ANSWER : Cl is limiting reagant. 54.3gAl(p)/27 = 2.01AI(P) Initial = 2.01 mol 2 mol divied = 2.01/2 2/3 = 1.005 =0.67 cl is smaller than al . can ...
Sunday, November 23, 2014 at 9:03am

Chemistry
The rusting of iron is represented by the equation 4Fe+3O2=2Fe2O. A 1.45-mol sample of iron, how many moles of Fe2O3 will there be after rusting has completed.
Sunday, November 23, 2014 at 2:23am

Chemistry
Calculate Ecell for reaction for the given info below.. O2(g)+2H2O(l)+4Ag(s)--> 4OH-(aq)+4Ag+(aq Ag+(aq)+ 1e ---> Ag(s) Ered= 0.80v O2(g)+2H2O(l) + 4e ---> 4OH- Ered= 0.40v My confusion is I have done problems similar to this when the Ered was negatives, but two ...
Sunday, November 23, 2014 at 12:43am

chemistry
Draw the three alkenes, each of formula C5H10, that will form 2-methylbutane upon hydrogenation.
Saturday, November 22, 2014 at 11:44pm

chemistry
Poly(methyl methacrylate) (PMMA), more commonly known as acrylic glass.Draw the monomer, given that this polymer forms by addition polymerization. Include all H atoms.
Saturday, November 22, 2014 at 11:44pm

Chemistry
A student was given a 2.45 g of impure potassium sulfate (K2SO4) sample. He dissolved this sample in 100 mL of water first and then added some barium chloride (BaCl2) solution. A 2.15 g of BaSO4 precipitate was obtained at the end of the reaction. What is the percent purity of...
Saturday, November 22, 2014 at 10:41pm

Chemistry
I have an assignment. It has two boxes to model the particles of the same gas at different temperature (18 and 45 degrees Celsius). I have to write two or three sentences relating the temperature, the average kinetic energy, and the motion of the particles in the two boxes. ...
Saturday, November 22, 2014 at 10:27pm

Chemistry
If I had a question about complex ions and the problem had a "mixture" of two compounds, how would I know if one of the products formed is going to be a solid or liquid? I know there are solubility rules, but is there something else you can use to tell?
Saturday, November 22, 2014 at 10:22pm

Chemistry
What is the mass of a sample of (NH4)2SO4 that contains 8.01 x 10^24 atoms of oxygen
Saturday, November 22, 2014 at 10:01pm

Chemistry
Calculate the volume of concentrated reagent required to prepare the diluted solution 17 M H3PO4 to prepare 939 mL of 6.7 M H3PO4
Saturday, November 22, 2014 at 9:53pm

physical chemistry
Please prepare 0.5L of 1.2M HCl in 50% (v/v) aqueous methanol. The details of HCl are as follows: Hydrochloric acid: Purity : 36%-38% Density : 1.18g/mL Physical state : liquid Molecular weight : 36.42 g/mol Describe the procedures and apparatus you need to use for the ...
Saturday, November 22, 2014 at 8:50pm

Chemistry
Which of the following chemical reactions is an example of an endothermic reaction? A. Making ice cubes from liquid water B. Burning a candle C. The evaporation of water D. The combustion of gasoline I think c
Saturday, November 22, 2014 at 7:41pm

chemistry
What is the purpose of a calorimeter? A. To determine the temperature of a chemical reaction B. To determine the energy changes of a chemical reaction C. To identify the specific temperature of an unknown substance I think the answer might be c
Saturday, November 22, 2014 at 7:35pm

Chemistry
Rates of Reactions I am conducting a experiment on increasing the rate of a reaction by increasing the surface area. For this I am reacting hydrochloric acid and marble chips. Variables:- -Independent: the mass of marble chips -Dependent: The volume of gas -Controlled: Temp of...
Saturday, November 22, 2014 at 6:13pm

Chemistry
Rates of Reactions I am conducting a experiment on increasing the rate of a reaction by increasing the surface area. For this I am reacting hydrochloric acid and marble chips. Variables:- -Independent: the mass of marble chips -Dependent: The volume of gas -Controlled: Temp of...
Saturday, November 22, 2014 at 5:09pm

Chemistry
An unknown metal with a mass of 260 g has a heat capacity of 100 J/oC. What is the specific heat of the metal? I am stuck finding the right equation, knowing that the mass is 260 g and heat is 100 J per Celsius. Thus, going with the equation, q=msT, the equation should fit in ...
Saturday, November 22, 2014 at 5:01pm

Chemistry
A volume of 725 mL of a gas is collected at 105 degrees celcius and 746 torr. The gas sample wights 1.92 grams. What is this gas?
Saturday, November 22, 2014 at 4:56pm

chemistry
Which of the following contains more thermal energy? A. Water at 100°C B. Ice at 0°C C. Water at 0°C D. Steam at 100°C I think d
Saturday, November 22, 2014 at 3:53pm

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