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September 26, 2016

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Physical Chemistry
If the n = 3 to n = 4 transition for a certain particle-in-a-box system occurs at 4.00 x 10^13 s -1 , find the frequency of the n =6 to n =9 transition in this system.
Tuesday, December 1, 2015 by Lorin

Chemistry
30.0 mL of 0.0200 mol/L NaOH are added to 70.0 mL of 0.0100 mol/L HCI. Calculate the [H3O+] and [OH─] of the resulting solution My answer: [OH-] = 1.00x10^-10 M; [H3O+] = 1.00x10^-4 M Teacher's answer: [OH-] = 1.00x10^-11 M; [H3O+] = 1.00x10^-3 M Am I missing ...
Tuesday, December 1, 2015 by Sam

chemistry
Approximately how many joules of heat are needed to raise the temperature of a 4.0-gram sample of water to 8.0C? that is all of the information that was provided
Tuesday, December 1, 2015 by Caroline

Chemistry
In which of the following substances does sharing of electrons between two atoms occur? He Nal PO43– Ag
Tuesday, December 1, 2015 by Sara

Chemistry
Which of the following elements is least likely to form a cation that will then form an ionic bond with an ion of a Group 7A element? S K Rb Fr
Tuesday, December 1, 2015 by Sara

oscotech
chemistry: is the formula to be used @ 25 degree c is E=Eo -(0.059/n(log a)) or Eo+(0.059/n)(log a)
Tuesday, December 1, 2015 by olagunju

Chemistry
Which of the following is a bond in which a metal transfers one or more electrons to a nonmetal? ionic bond hydrogen bond metallic bond covalent bond
Tuesday, December 1, 2015 by Sara

Chemistry
A 0.600 m aqueous solution of KBr has a total mass of 69.0 g. What masses of solute and solvent are present?
Tuesday, December 1, 2015 by Troy

chemistry
make 100ml of 0.50mol/L CuSO4 by diluting part of the 0.100 mol/L
Tuesday, December 1, 2015 by Anonymous

Organic Chemistry
Which is more polar trans-methyl cinnamate or trans-chalcone?
Tuesday, December 1, 2015 by Bianca

Chemistry
If you place 1.26 g of solid silicon in a 6.54 L flask that contains CH3Cl with a pressure of 634 mm Hg at 25°C, what mass of dimethyldichlorosilane, (CH3)2SiCl2(g), can be formed?
Tuesday, December 1, 2015 by Julian

Chemistry
The ionization energies (kJ/mol) of hydrogen (H), nitrogen (N), sodium (Na), and oxygen (O) are 1,312, 1,402, 1,681, and 1,314, respectively. Which element combination is least likely? OH– NO3– NH4+ NaO–
Tuesday, December 1, 2015 by Sara

Chemistry
Which of the following is a monatomic cation? Br NH4+ SO42– Fr+
Tuesday, December 1, 2015 by Sara

Chemistry
The population ratio between two energy levels separated by 1.4 ✕ 10−22 J is 0.69. What is the temperature of the system?
Tuesday, December 1, 2015 by Anonymous

Chemistry
Which of the following elements is most likely to form an ion that will then form an ionic bond with an ion of a Group 1A element? Pt I Fr Be
Tuesday, December 1, 2015 by Sara

Chemistry
How many grams of water are needed to make at least 50.0g of C2H2 in this reaction? CaC2 + 2H2O = Ca(OH)2 + C2H2 The numbers inside are suppose to be small but you can't do that on a laptop... Thanks
Tuesday, December 1, 2015 by Jake

Chemistry
The population ratio between two energy levels separated by 1.4 ✕ 10−22 J is 0.69. What is the temperature of the system?
Tuesday, December 1, 2015 by Anonymous

Chemistry
Calculate the hydronium and hydroxide concentration of a solution made by mixing 100 mL 0.020 mol/L NaOH and 25.0 mL of 0.040 mol/L HCl. I'm having trouble knowing where to start with this question.
Tuesday, December 1, 2015 by Hal

Chemistry
50 Ltr. Of a certain liquid is confined in a piston system at the extenal pressure 100 atm this pressure suddenly released and liquid is expanded against a contant atm pressure , vol. Of liquid increases by 1 Ltr and the final pressure of the liquid is 10 atm. Find the work done.
Tuesday, December 1, 2015 by Sam

algebra
in a class of 30 students , there are 22 students who study chemistry but not physics, 4 who study physics but not chemistry and who study neighter chemistry nor physics. how many students in the class study physics
Tuesday, December 1, 2015 by judith

Chemistry
A buffer solution contains 0.052 M HC2H3O2 and 0.025 M NaC2H3O2. The pH of this solution is _____. Ka for HC2H3O2 is 1.8x10-5.
Tuesday, December 1, 2015 by Morgan

Chemistry
A substance undergoes a first-order decomposition. After 40.0 min at 500 degrees C, only 12.5% of the original sample remains. What is the half-life of the decomposition? If the original sample weighted 243 g, how much would remain after 2 hours?
Monday, November 30, 2015 by Bob

Miami trace
Chemistry. AN UNKNOwn gas has a pressure of 2.0, a volume of 15.0 L and a temperature of 348 Kelvin. The sample weighs 4.20 grams. What is its molecular weight. I am trying to find formula
Monday, November 30, 2015 by corey

Chemistry
How many molecules of silicon triiodide are present given 450.0 grams of the compound?
Monday, November 30, 2015 by Bigrol111

Chemistry
An aqueous antifreeze solution is 40.0% ethylene glycol (C2H6O2) by mass. The density of the solution is 1.05 g/cm3. Calculate the molality, molarity, and mole fraction of the ethylene glycol. molality I actually can do this whole problem EXCEPT for one part I'm stuck on. ...
Monday, November 30, 2015 by Kyle

Chemistry
A piece of copper alloy with a mass of 73.0 g is heated from 23.0◦C to 44.0◦C. In the process, it absorbs 558 J of energy as heat. What is the specific heat of this copper alloy?
Monday, November 30, 2015 by Sam

Chemistry
Calculate the heat released when 1.00L of Cl2 (g) with a density of 1.88g/L reacts with an excess of sodium metal at 25 degrees C and 1 atm to form sodium chloride.
Monday, November 30, 2015 by Emily

chemistry
If 150.0 g of copper at 100.0 C and 125.0g of liquid water at 35.0 C are mixed in an insulated container, what is the final temperature of the mixture? Ccu= .39 J/g C Cwater= 4.184 J/g C Did i do this correct: 150.0 x 100.0 x .39 = 250 J 125.0 x 35.0 x 4.184 = 18300 J 18300 + ...
Monday, November 30, 2015 by miyabi

Chemistry
Approximately how many joules of heat are needed to raise the temperature of a 4.0-gram sample of water to 8.0C?
Monday, November 30, 2015 by Caroline

chemistry
If 150.0 g of Zinc at 100.0 C and 250.0g of liquid water at 10.0 C are mixed in an insulated container, what is the final temperature of the mixture? Czn= .39J/g C Cwater= 4.184J/g C Are we looking for the delta T? If we are, how do you find Q (joules) Thank you!
Monday, November 30, 2015 by miyabi

Chemistry
I wrote the balanced equation for cream of tartar and baking soda: NaHCO3+KHC4H4O6->KNaC4H4)6+H2CO3 I identified the conjugate acid base pairs: NaHCO3 and H2CO3, KHC4H4O6 and KNaC4H4O6 I wrote a balanced equation for carbon dioxide gas and water: H2CO3->H2O+CO2 I ...
Monday, November 30, 2015 by Bridget

chemistry
Two substance have the same mass and are both initially at 15.0 C. They both absorb 110 J energy. Which substance will have the higher temperature, the one with the higher or lower specific heat? Explain
Monday, November 30, 2015 by miyabi

chemistry
calculatat400 would you expect the reaction to be more or less product oriented that at 350c?explain
Monday, November 30, 2015 by anonymous

Chemistry
Are the following True or False? If false, explain why. (I put what I think the answers are below each question) 1) Iron metal will reduce Fe3+ to Fe2+ (False because Fe3+ is more stable than Fe2+?) 2) Copper metal will dissolve in nitric acid, liberating NO gas (True) 3) ...
Monday, November 30, 2015 by Anonymous

chemistry
How do you work out the pKa of a substance from the titration curve that has two equivalence points?
Monday, November 30, 2015 by Adam

chemistry
0.443g of silver metal was obtained wen 0.784g of silver nitrate decomposes. What is the percentage yield of the reaction
Monday, November 30, 2015 by David soye

chemistry please help me understand this
What is the charge on Pd when it is coordinated with triphenylphosphine? PPh3. Pd(PPh3)4 .... Google tells me the PPh3 is a neutral ligand, how can this be if the metal has to have a charge associated with it?
Monday, November 30, 2015 by paul

chemistry
Which response has both answers correct? Will a precipitate form when 250 mL of 0.33 M Na2CrO4 are added to 250 mL of 0.12 M AgNO3? [Ksp(Ag2CrO4) = 1.1 „e 10¡V12] What is the concentration of the silver ion remaining in solution?
Monday, November 30, 2015 by farahn

Chemistry Dr BOB
A voltaic cell has one half-cell with a Cu bar in a 1.00 M Cu2+ salt and the other half-cell with a Cd bar in the same volume of a 1.00 M Cd2+ salt. Report your answers to the correct number of significant figures. a)Find E degree cell, delta G degree , and K. b)As the cell ...
Sunday, November 29, 2015 by Patrick

Chemistry
How to find the mass of a solid formed when: 45.00ml solution of 0.003 800 mol/L lead (II) nitrate is mine dish a 30.00 mL solution of 0.08800 mol/L strontium iodide
Sunday, November 29, 2015 by Sam

chemistry Dr. BOB
A voltaic cell has one half-cell with a Cu bar in a 1.00 M Cu2+ salt and the other half-cell with a Cd bar in the same volume of a 1.00 M Cd2+ salt. Report your answers to the correct number of significant figures. a)Find E degree cell, delta G degree , and K. b)As the cell ...
Sunday, November 29, 2015 by Patrick

Chemistry
what mass of barium carbonate will dissolve in a 2.50L solutions of 0.0500 molar sodium carbonate
Sunday, November 29, 2015 by Sam

Chemistry
Determine the number of moles of N2 that are required to produce 12 mol of NH3 using the equation, N2 + 3H2 --> 2NH3. 12 mol NH3 x 1 mol N2/2 mol NH3 = 6 moles of N2.
Sunday, November 29, 2015 by Beth

Chemistry Dr Bob
A voltaic cell has one half-cell with a Cu bar in a 1.00 M Cu2+ salt and the other half-cell with a Cd bar in the same volume of a 1.00 M Cd2+ salt. Report your answers to the correct number of significant figures. a)Find E degree cell, delta G degree , and K. b)As the cell ...
Sunday, November 29, 2015 by Patrick

Chemistry
Which solution will have the lowest pH? a. 0.10 M HClO2, pKa = 1.96 b. 0.10 M HCN, pKa = 9.21 c. 0.10 M HF, pKa = 3.19 d. 0.10 M HClO, pKa = 7.538 e. 0.00010 M HCl Does the lower the pka stronger the acid, means the lower the ph, so the answer is A?
Sunday, November 29, 2015 by Anonymous

Chemistry
If you want to prepare 2.0 liters of a .25 M solution of NH4Cl, how many grams of the salt should you weigh out?
Sunday, November 29, 2015 by J

Chemistry
Sulfuric acid is produced commercially by the reactions indicated below at the appropriate percent yields for each step. The second step utilizes air as a source of oxygen and heats it to 4000C in the presence of vanadium (V) oxide, a catalyst. Assuming air is 21% oxygen by ...
Sunday, November 29, 2015 by Adam

Chemistry
If 5.026g chromium is combined with 3.04L of chlorine gas at 0.955atm and 220C, what mass of chromium (III) chloride is produced?
Sunday, November 29, 2015 by Adam

Chemistry Dr BOB
A voltaic cell has one half-cell with a Cu bar in a 1.00 M Cu2+ salt and the other half-cell with a Cd bar in the same volume of a 1.00 M Cd2+ salt. Report your answers to the correct number of significant figures. a)Find E degree cell, delta G degree , and K. b)As the cell ...
Sunday, November 29, 2015 by Patrick

chemistry
In the preparation of ammonia, why should the mixture of ammonium chloride and calcium hydroxide be a paste, not dry powder?
Sunday, November 29, 2015 by clive

Chemistry
The population ratio between two energy levels separated by 1.4 ✕ 10−22 J is 0.69. What is the temperature of the system?
Sunday, November 29, 2015 by Anonymous

Chemistry- Dr.Bob
Why is cis-PCl3F2 polar and trans-PCl3F2 nonpolar?
Saturday, November 28, 2015 by Sanaya

Math
In chemistry class, each of the 82 students needs 72 mL of base. How many one- liter bottles of base need to be available? Help?
Saturday, November 28, 2015 by kristine

CHEMISTRY URGENT HELP
How to draw line graph for showing changes in test tubes while showing that exhaled air contains more carbon dioxide than inhaled air
Saturday, November 28, 2015 by mark

chemistry
You want to prepare 500 ml of 1.0M acetic acid from a 17.4 M stock solution.What volume of stock solution is required?
Saturday, November 28, 2015 by omar

Chemistry
The intreval volume of a clorimeter was1.12L. A sample of gas of 1.863g of nonae was added, and the closed calorimeter then had added oxygen until the pressure was 10.0atm na dht etemp was 23.1 C.Write the full balanced equation of the combustion of the nonae in the ...
Saturday, November 28, 2015 by sarah

Chemistry
If 34.3 mL of barium hydroxide are required to neutralize 15.9 mL of the acid, what is the molarity of the hydrochloric acid solution?
Saturday, November 28, 2015 by Kaitlin

chemistry DR BOB
A voltaic cell has one half-cell with a Cu bar in a 1.00 M Cu2+ salt and the other half-cell with a Cd bar in the same volume of a 1.00 M Cd2+ salt. Report your answers to the correct number of significant figures. a)Find E degree cell, delta G degree , and K. b)As the cell ...
Saturday, November 28, 2015 by Patrick

Chemistry
The population ratio between two energy levels separated by 1.4 ✕ 10−22 J is 0.69. What is the temperature of the system?
Saturday, November 28, 2015 by Anonymous

Chemistry
Find the volume of 0.250M sulfuric acid necessary to react completely with 79.3g sodium hydroxide
Saturday, November 28, 2015 by Tiffany

chemistry
When a 10 g sample of copper oxide is reduced by heating in the presence of carbon monoxide, how many moles of copper are formed?
Saturday, November 28, 2015 by sara

physical chemistry
calculate the mass of NaCl needed to prepare 1000cm of 0.025M solution (molar mass of NaCl is 58.5)
Saturday, November 28, 2015 by Anonymous

chemistry
500 calories are added to 100 gram copper at 25 degree celsius a.what will be the final temperature? b.if the same amount of heat was added to an equal amount of water,what would be the final temperature?
Friday, November 27, 2015 by jhanz

Chemistry
For a Sc atom in ground electronic state: 1. how many electrons are there in 4s orbitals? 2. how many electrons are there in 3d orbitals? 3. how many electrons are there in 4p orbitals? 4. how many unpaired electrons are there? 5. to what block does Sc belong to in the ...
Friday, November 27, 2015 by S

Chemistry
The population ratio between two energy levels separated by 1.4 ✕ 10−22 J is 0.69. What is the temperature of the system?
Friday, November 27, 2015 by Anonymous

Chemistry
Consider the 5p orbital of a hydrogen atom. 1. how many different 5p orbitals are there? 2. how many radial nodes are there? 3. how many angular nodes are there? (i.e. how many nodal planes or surfaces, not including radial nodes)
Friday, November 27, 2015 by S

Chemistry
A toothpaste contains 0.220 % by mass sodium fluoride used to prevent dental caries and 0.32 % by mass triclosan C12H7Cl3O2, an antigingivitis agent. One tube contains 119 g of toothpaste. How many fluoride ions, F−, are in the tube of toothpaste? How many grams of ...
Friday, November 27, 2015 by xyz

Chemistry
In photosynthesis, glucose, C6H12O6, and O2 are produced from CO2 and H2O. Glucose from starches is the major fuel for the body. 6CO2(g)+6H2O(l)+680kcal⟶ C6H12O6(aq)+6O2(g) How much heat, in kilojoules, is needed to produce 22.5 g of C6H12O6?
Friday, November 27, 2015 by veen

Chemistry
When CH3OH at its normal boiling point, does its entropy increase or decrease? Explain. - My opinion The entropy decreases because there is less order due to the less randomness of gas particles favoured when such an element is boiled not at normal boiling point?
Friday, November 27, 2015 by Liam

Chemistry
calculate the molar solubility of BaCO3 in a 0.10M solution of NaCo3 (aq). (ksp(BaCO3)=8.1x10^-9)
Friday, November 27, 2015 by Kia

Chemistry
A 0.200 g sample of carbon dioxide, CO2, has a volume of 525 mL and a pressure of 473 mmHg . What is the temperature of the gas in kelvins?
Friday, November 27, 2015 by joey

Chemistry
How many joules are needed to change 163.34 g of water at 54.1 °C to steam at 100 °C?
Friday, November 27, 2015 by Miles

Chemistry
What would the volume be of 0.955g of propane at 735 torr and 35.00C? And How many mols of xenon would be required to create a mixture with a mole fraction of xenon of 0.0190 if the mixture were also to contain 2.16mol argon and 3.612g neon? Thanks in adavance
Friday, November 27, 2015 by Adam

Chemistry
Water is a liquid at STP. Hydrogen sulfide, H2S, a heavier molecule, is a gas under the same conditions.Explain, using diagrams, why this is so.
Friday, November 27, 2015 by Neishia

Chemistry
A concentrated H2SO4 solution is 10.5 M. You have to make 255 mL of 0.650 M solution. How would you prepare it?
Friday, November 27, 2015 by Neishia

Chemistry
Benadryl is an over-the-counter drug used to treat allergy symptoms. The formula of benadryl is C17H21NO. How many moles of C are present in 0.759 mole of benadryl?
Friday, November 27, 2015 by tom

Chemistry
what volume of oxygen at 423.0K and a pressure of 127.4kPa will be produced by the decomposition of 129.7g barium peroxide to form barium oxide and oxygen gas? Thank you
Friday, November 27, 2015 by Adam

Chemistry
how you would prepare 250 mL of 0.25 M NaOH from solid NaOH and water?
Friday, November 27, 2015 by Neishia

Organic Chemistry
What is the optical purity of a partially racemized product is the calculated specific rotation is -8◦ and the pure enantiomer has a specific rotation of -10◦? Calculate the percentage of each of the enantiomers in the partially racemized product. I'm very lost...
Friday, November 27, 2015 by nicole

Chemistry
The theoretical yield of a reaction is the amount of product obtained if the limiting reactant is completely converted to product. Consider the reaction: P4(s) + 6 Cl2(g) → 4 PCl3(l) If 19.47 g P4 is mixed with 6.85 g Cl2, calculate the theoretical yield (g) of PCl3 ...
Thursday, November 26, 2015 by Riley

Chemistry
A Sample of propane, C3H8, occupies 5.00L at 270C and 309torr. The volume of the canister is changed to 1.85L while the pressure remains constant. What is the Temperature, in K and 0C, of the gas after the change? What would be the setup for this problem? Thank you.
Thursday, November 26, 2015 by Adam

Chemistry
A sample of oxygen occupies 38.9L at STP. What will the pressure need to be in Torr. if the volume is to be changed to 32.2L without a change in T. Is this P1V1/T2=P2V2/T2? How would I set it up.
Thursday, November 26, 2015 by Johnny

Chemistry
Assume you have prepared 100.0 mL of a buffer solution using 0.400 mol of acetic acid (pKa = 4.74) and 0.400 mol of sodium acetate. The pH of this buffer solution is initially 4.74. After preparing this buffer solution, you added 55.0 mL of a 1.10 M NaOH solution to your ...
Thursday, November 26, 2015 by J

Chemistry
A chemist needs to prepare a buffer using the carbonate system (information in the table in the previous quetion) with a final pH of 10. Which components should they mix in water to product this buffer? Question options: H2CO3 HCO3- CO32-
Thursday, November 26, 2015 by J

Chemistry
A chemist needs to prepare a buffer using the carbonate system (information in the table below) with a final pH of 6. Which components should they mix in water to product this buffer? H2CO3 HCO3- CO32- pKa 6.35 10.33 N/A
Thursday, November 26, 2015 by J

Chemistry
The pH of a buffer can be predicted using the Hendersen-Hasselbach equation: pH=pKa+ log([conjugate base][conjugate acid]) The choice of the conjugate acid-base pair (as you did in the previous questions) determines the pKa value to be used in the H-H equation. By varying the ...
Thursday, November 26, 2015 by J

Chemistry
6.2g of NaOH is added to 800ml of water What is the molarity of the solution? What is the pH?
Thursday, November 26, 2015 by Tegan

Chemistry
The equilibrium constant for Br2 + Br <-> Br3 at 25 degrees is 18. Calculate the equilibrium constant Br3 <-> Br2 + Br
Thursday, November 26, 2015 by Lori

Chemistry - Energy Phase Changes
Calculate the quantity of heat gained or lost in the following change: 0.44 mol of water evaporates at 100 degrees Celsius - So what I did was: 1 mol -> 6.01 kJ 0.44 mol -> x x = 2.64 kJ of energy gained But apparently this is incorrect? Could somebody please explain to ...
Wednesday, November 25, 2015 by Kid

chemistry
How many grams of bismuth (III) chloride can be produced from 575 mL of chlorine gas at STP when reacting with excess bismuth metal?
Wednesday, November 25, 2015 by nicholas

Chemistry
Automotive airbags inflate when sodium azide, NaN3, rapidly decomposes to its constituent elements according to the chemical equation, 2 NaN3 -> 2 Na + 3 N2. How many grams of nitrogen are produced when 1000 milligrams of sodium azide decomposes?
Wednesday, November 25, 2015 by Sarah

chemistry
how many molecules are present in a 750 ml of C6H12O6
Wednesday, November 25, 2015 by Anonymous

Chemistry
Write the formulas of the compounds formed by NH4+ with the following anions: CN-, ClO3-, SO42-, H2PO4-
Wednesday, November 25, 2015 by Kim

Chemistry
A sample of air was passed through an electrical discharge causing the following reaction N2(g) + O2(g)->2NO(g) . Assuming that 1.00 mole of air (78% N2, 21% O2) was originally present at 1.00 atm, determine the partial pressure (in atm) of NO at equilibrium. Kp = 0.0123 at...
Wednesday, November 25, 2015 by Anonymous

chemistry
explain how you would obtain solid lead carbonate from a mixture of lead carbonate and sodium carbonate powder
Wednesday, November 25, 2015 by diane

Chemistry
1.)An ammonia/ammonium buffer solution contains 0.35 M NH3 and 0.72 M NH4+. The Kb value of ammonia is 1.8×10−5. Calculate the pH of this buffer. 2.) Nitrous acid has a Ka of 4.5×10−4. What is the pH of a buffer solution containing 0.15 M HNO2 and 0.20 ...
Wednesday, November 25, 2015 by LuigiR

Chemistry
How many miles of oxygen would it take to react with 1.0 moles of magnesium
Tuesday, November 24, 2015 by Abby

Chemistry
A student adds 3.50 g of dry ice (solidCO2 ) to an empty balloon. What will be the volume of the balloon at STP after all the dry ice sublimes (converts to gaseousCO2 )?
Tuesday, November 24, 2015 by Diamond

Chemistry
When a 10 g sample of copper oxide is reduced by heating in the presence of carbon monoxide, how many moles of copper are formed?
Tuesday, November 24, 2015 by Leo

international university of east africa.chemistry
20cm of sulphuric acid required 18.5cm of 0.1M sodium hydroxide solution for complete neutralisation.
Tuesday, November 24, 2015 by cosmas

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Homework Help: Science