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September 1, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Chemistry
H3PO4 Ka1= 7.5x10^-3 Ka2= 6.2x10^-8 Ka3=4.2x10-^13 Explain how you will make a buffer with a pH of 11.80 using solid Na2HPO4 and either 2.00 M NaOH or 2.00 M HCL. The most concentrated component should have a concentration of 0.50 M, and you need to make 2.50 liters of this ...
Tuesday, March 5, 2013 by Celina Sandoval

Chemistry
If you have 1.90 mol of H_2 , how many grams of NH_3 can be produced?
Tuesday, March 5, 2013 by Nancy

Chemistry
If you have 1.90 mol of H_2 , how many grams of NH_3 can be produced?
Tuesday, March 5, 2013 by Nancy

Analytical Chemistry
Serum taken from a patient being treated with lithium for manic-depressive illness was analyzed for lithium concentration. A reading of 291 units was obtained for the intensity of the 671 nm red emission line. Then 1.00 mL of a 11.7 mM Lithium standard was added to 9.00 mL of ...
Tuesday, March 5, 2013 by Brian

Chemistry
I-I:150 F-F:160 C-C:350 H-H:435 (a) Calculate the energy of the I-F bond. Express your answer in units of kJ/mol. unanswered (b) Calculate the % ionic character of the I-F bond.
Tuesday, March 5, 2013 by Anonymous

Chemistry
dentify which bond you would expect to be the most polar. H-C H-F H-Cl H-S
Tuesday, March 5, 2013 by Anonymous

Chemistry
Which compound would you expect to have the lowest melting point? Base your answer off of the bonding theory presented in this course. MgO BeS NaCl KCl
Tuesday, March 5, 2013 by Anonymous

Chemistry
Which compound would you expect to have the highest melting point? Base your answer off of the bonding theory presented in this course.
Tuesday, March 5, 2013 by Anonymous

Chemistry
Chlorofluorocarbons (CFC's) are organic compounds that have been implicated in ozone depletion. When the CFC known as Freon 12 (CCl2F2) is exposed to UV radiation (wavelength in the range of 10 nm to 400 nm, a bit shorter than visible light), a chlorine atom breaks off ...
Tuesday, March 5, 2013 by Anonymous

Chemistry
Estimate the radius of the cesium ion, Cs+. The lattice energy of cesium chloride, CsCl, is 633 kJ/mol. For CsCl, the Madelung constant M is 1.763, and the Born exponent n is 10.7. The radius of Cl− is known to be 1.81 A˚. Express your answer in Angstroms.
Tuesday, March 5, 2013 by Anonymous

chemistry
if [NO]=2M , [N2] = 1M, and [O2]= 1M, is the reaction at equilibrium?
Tuesday, March 5, 2013 by Anonymous

chemistry !
a 135-g sample of sea water is evaporated to dryness, leaving 4.73 g of solid residue (the salts formerly dissolved in the seawater). calculate the mass percent of solute present in the original sea water. please help I need to pass this test. thank you thank you forever!!!!!
Monday, March 4, 2013 by Eleanor

chemistry please help!!
what is the net ionic equation for the reaction between a strong acid and a strong base? what does it mean by this question?/ (: thanks.
Monday, March 4, 2013 by yvette

chemistry
What volume of oxygen would be required for the complete combustion of 23.4g of benzene, C6PO4?
Monday, March 4, 2013 by ally

Chemistry
How much heat (kcal)is needed to melt 14 ice cubes? Each cube is at 0c and has a mass of 28grams.
Monday, March 4, 2013 by Brittany

Chemistry
A buffer consists of 0.16 M KHCO3 and 0.39 M K2CO3. Carbonic acid is a diprotic acid with Ka1 = 4.5 10-7 and Ka2 = 4.7 10-11. (a) Which Ka value is more important to this buffer? Ka1 Ka2 I don't understand this one at all. How do I determine which Ka value is more ...
Monday, March 4, 2013 by Edward

Chemistry
An industrial chemist studying bleaching and sterilizing prepares several hypochlorite buffers. Find the pH of the following buffers. (a) 0.090 M HClO and 0.090 M NaClO (b) 0.090 M HClO and 0.135 M NaClO (c) 0.135 M HClO and 0.090 M NaClO (d) One liter of the solution in part...
Monday, March 4, 2013 by Edward

physical chemistry
This question is about a lab called Heats of Ionic Reaction in my Physical Chemistry class. I need to know why there should be a large percentage error in deltaH4
Monday, March 4, 2013 by shelby

Chemistry
What is the significance of the distance between two metals in the activity series?
Monday, March 4, 2013 by Katherine

chemistry
An aqueous solvent of NaCl has a melting point of –165C How many moles of NaCl are present in a 189 g solvent?
Monday, March 4, 2013 by breseida

Chemistry
Ammonia is used as a fertilizer throughout the world. It is often produced by reacting nitrogen gas with hydrogen gas in a synthesis reaction. How much ammonia in grams can be produced from 9207 grams of nitrogen and 44 000 L of hydrogen?
Monday, March 4, 2013 by Michelle

Chemistry
How much heat (in Joules) is needed to raise the temperature from -79oC to 57oC for 31.5g of water? I remember my teacher using different temperatures for each equation, can someone show me what that is? thanks.
Monday, March 4, 2013 by Denny

Honors Chemistry
When 6 grams of acetic acid and 8.4 grams of sodium bicarbonate react, how many moles of CO2 is produced? I don't know how to show the work.
Monday, March 4, 2013 by Brandie

Chemistry
In the equation Q = mc(deltaT), I learned that Q means heat transfer. Is it the heat transfer from the system to the surroundings, i.e. the system loses/absorbs heat or is it from the surroundings to the system? A couple of places on the Internet say that Q is the heat energy ...
Monday, March 4, 2013 by a Canadian

chemistry
Calculate the molar concentration of OH− ions in an 1.79 M solution of hypobromite ion (BrO−; Kb = 4.0 10-6).
Monday, March 4, 2013 by sara

Chemistry
Calculate the mass percent composition of carbon in each the following carbon compounds. C2H2 C3H6 C2H6 C2H6O
Monday, March 4, 2013 by Amee

chemistry
Phenylacetic acid (C6H5CH2COOH) is one of the substances that accumulates in the blood of people with phenylketonuria, an inherited disorder that can cause mental retardation or even death. A 0.021 M solution of C6H5CH2COOH has a pH of 2.99. Calculate the Ka value for this ...
Monday, March 4, 2013 by hannah

Chemistry
in an experiment, ammonia gas, NH3(g) was bubbled through distilled water. Some of the dissolved ammonia gas, NH3, reacted with the water to form the aqueous ammonia ions, NH4. When red litmus paper was placed in contact with the aqueous solution, the paper turned blue. This ...
Monday, March 4, 2013 by Joe

Chemistry
Calculate the morality of a solution that contains a 4.0 mol of a solute dissolved in 12.0L of solution
Monday, March 4, 2013 by Francesca

Chemistry
Suppose a can of aerosol contains a residual amount of gas at pressure of 755mm Hg and a temperature of 25C. What would the presure be if the can were to be heated to 1155c?
Monday, March 4, 2013 by Amee

Chemistry
A beaker of nitric acid is neutralized with calcium hydroxide. Write a balanced molecular equation and a net ionic equation for his reaction
Monday, March 4, 2013 by Amee

Chemistry
Caslcualte the formula massfor each of the following compunds CS2 C6H12O6 Fe(nO3)3 C7H16
Monday, March 4, 2013 by Amee

Chemistry
1) Determine the Kc for the following experimental conditions: compound A+compound B --> Compund D Compound: A B M 0.003 0.0023 Volume used: 5 mL 8 mL Total volume = 25 mL, using graph 2 and a %T of 24 for compund D molecular weight compund D = 535 g/mol 2) Determine Kc for...
Monday, March 4, 2013 by Anonymous

Chemistry
You are given a compound with an unknown concentration and you have five samples with known concentration of the compound. List 3 pieces of information you need to determine in order to calculate the unknown concentration spectrophotometrically.
Monday, March 4, 2013 by Anonymous

college chemistry
if my sublimation apparatus imploded, what was the cause of it?
Monday, March 4, 2013 by Anonymous

Analytical Chemistry
How many milliliters of 0.0560 M EDTA are required to react with 50.0 mL of 0.0170 M Cu^2+? With 50 mL of 0.0170 M Sc^3+? My work so far: (50mL)(0.0170mmol/mL)= 0.85 mmol Cu^2+ I'm not sure how to do the rest. Please help.
Monday, March 4, 2013 by Sam

Chemistry
Hess's law _____. A.) makes it possible to calculate H for complicated chemical reactions B.) states that when you reverse a chemical equation, the sign of H does not change C.) determines the way a calorimeter works D.) describes the vaporization of solids Please help - I...
Monday, March 4, 2013 by Jack

chemistry
A white solid was found in an unmarked bag. Describe an experiment that can be set up to determine if the solid is either MgSO4*10H2O or KCL*2H2O
Monday, March 4, 2013 by Rachel

chemistry
the equilibrium constant of the decomposition of NOCL is 1.6*10^-5. calculatethe concentration of all species at equilibrium if initially 3.52 mol of NOCL is placed in a 5.00 L container
Monday, March 4, 2013 by nancy

chemistry
A sample of oxygen that occupies 1.00x10^6 mL at 575 mm Hg is subjected to a pressure of 1.36 atm. What will the final volume of the sample be if the temperature is held constant? How would I set up this equation?
Monday, March 4, 2013 by kate

Chemistry -need help in solving problem
The solubility of a gas at 7.0 atm of pressure is 0.52 g/L . How many grams of the gas would be disolved per 1.0 L if the pressure increased 40 percent?
Monday, March 4, 2013 by Joy

chemistry
calculate the volume of the hydrogen that will combine with 40 litres of oxygen to form steam at 150 C and atmospheric pressure
Monday, March 4, 2013 by bidha

Chemistry
1. Hess's law _____. A.) makes it possible to calculate H for complicated chemical reactions B.) states that when you reverse a chemical equation, the sign of H does not change C.) determines the way a calorimeter works D.) describes the vaporization of solids Please help...
Monday, March 4, 2013 by Jack

chemistry
calculate the volume of the hydrogen that will combine with 40 litres of oxygen to form steam at 150 C and atmospheric pressure
Monday, March 4, 2013 by bidha

chemistry
Some spacecrafts use hydrazine (N2H4) as fuel and is burned according to the following reaction: N2H4(l)+N2O4(g)=>2 N2O(g)+2 H2O(g) Calculate the DHrxn° for this reaction using the standard enthalpies of formation from Appendix IIB. Calculate your answer to 4 sig figs
Monday, March 4, 2013 by Brandi

chemistry quick homework help
What is the molecular geometry surrounding the carbon atom in CI4? (This compound contains the elements caron and iodine, not chlorine.) trigonal planer pyramidal (trigonal pyramidal) bent (angular) linear tetrahedral
Monday, March 4, 2013 by will.i.am

Chemistry
The solubility of a gas at 7.0 atm of pressure is 0.52 g/L . How many grams of the gas would be disolved per 1.0 L if the pressure increased 40.0 percent?
Monday, March 4, 2013 by Joy

chemistry
Hey, I was just struggling with a question that I need to figure out to help me with my next lab, so if any of you guys could help me that would be greatly appreciated. Question: write a balanced equation for the reaction between H2O2 and acidified MnO4-
Monday, March 4, 2013 by alex

Chemistry
I want to have the details of the experiment title: Determine the equilibrium constant of a reversible reaction involving the iodine and the tri iodate ion reaction and also determine the gibbs free energy of the reaction.
Monday, March 4, 2013 by Rani

Math
Stupid question time. I need to figure out how to rearrange equations to solve for x in my chemistry homework, which involves putting equations in quadratic form first. But I can't for the life of me remember how to "rearrange" them correctly. So what in the step...
Monday, March 4, 2013 by Marcus

Analytical Chemistry
How many milliliters of 0.202 M KOH should be added to 500.0 mL of 0.0233 M tartaric acid (C4H6O6; FW 150.087) to adjust the pH to 2.75? Ka1 = 1.0 x 10-13 and Ka2 = 4.6 x10-5. For this one, the Ka1 seems sort of off. The pka would be 13 which doesn't make sense.
Monday, March 4, 2013 by Micki

Chemistry
A 1.44-g sample of an unknown pure gas occupies a volume of 0.336 L at a pressure of 1.00 atm and a temperature of 100.0 degrees Celsius. What is the unknown gas?
Monday, March 4, 2013 by Lily

Chemistry
A 1.44-g sample of an unknown pure gas occupies a volume of 0.336 L at a pressure of 1.00 atm and a temperature of 100.0 degrees Celsius. What is the unknown gas?
Monday, March 4, 2013 by Lily

Chemistry
Consider the titration of 25.00 mL of 0.08364 M pyridine (see structure below) with 0.1067 M HCl. Find the pH at the following acid volumes (Va): 4.63 mL, Ve, and 25.0 mL. pKa = 11.3 I got 11.81, 6.63, and 1.74 respectively. Yet, the last two are incorrect and I am unsure what...
Monday, March 4, 2013 by Angelyka

chemistry
What is the mole ratio between all compounds of this reaction:HC2H3O2 + NaHCO3 = NaC2H3O2 + H2O + CO2
Sunday, March 3, 2013 by Jeanne

general chemistry
In an appropriate reference read a dicussion of mass and volume measurements
Sunday, March 3, 2013 by kiara

chemistry
If 5.30mL of 0.1000 M NaOH solution is needed to just neutralize excess acid after 20.00 mL of 0.1000 M HCl was added to 1.00 g of an antacid, how many moles of acid can the antacid counteract per gram?
Sunday, March 3, 2013 by Liz

chemistry
a solution is made that is 1.5X10^-3M in Zn(NO3)2 and 0.130 M in NH3. the Kf for Zn(NH3)4^2+ is 2.0X10^9
Sunday, March 3, 2013 by Anonymous

Chemistry
What is 431804 and 10235.0 rounded to four significant figures?
Sunday, March 3, 2013 by Juan

Chemistry
1.) A 3.000gram sample of a hydrate compound containing Co, C2O4, and H2O was combusted to give 1.316g of Co3O4. What is the percentage of Cobalt in the oxide? 3.) 2.000 grams of a sample containing Co, C2O4, and H2O showed there to be 0.9621g of oxalate in the sample. Was is...
Sunday, March 3, 2013 by Robert

chemistry
A lab technician determines the boiling point elevation of an aqueous solution of a nonvolatile, nonelectrolyte to be 1.62°C. What is the solution's molality?
Sunday, March 3, 2013 by Catherine

Chemistry II
Saw this one already answered, but did not understand at all... Calculate the delta Hf of C6H12O6 (s) from the following data: Delta H combustion= -2816 kj/mol delta Hf of Co2 = -393.5 kj/mol delta Hf= of H2 O= -285.9kj/mol
Sunday, March 3, 2013 by Scooby

Chemistry
Factors affecting reaction rate. Use collision theory to explain. Factor: nature of the reactant Affect on rate: more or less reactive based on its chemical identity. reactivity: aq>g>l>s Explanation: For the other factors, we had to explain it based on whether the ...
Sunday, March 3, 2013 by a Canadian

Chemistry
50 mL of copper(II) sulfate reacts with 50 mL of sodium hydroxide. Their concentrations are 0.3 M and 0.6 M respectively. The temperature increased to 23.6 C from 23.4 C. Determine the enthalpy change for the reaction in kJ/mol of sodium hydroxide. Q=mcΔT =(50g + 50g)(4....
Sunday, March 3, 2013 by a Canadian

analytical chemistry
Low concentration replicate samples of Pb-EDTA gave the following counts in a mass spectral measurement: 188.3, 145.9, 159.7, 174.7, 143.7, 213.1, 164.7, 169.3, 158.7, 176.3. Ten measurements of a blank had a mean of 27.3 counts. A sample containing 1.00 ìM Pb-EDTA gave...
Sunday, March 3, 2013 by holly

Chemistry
What is the difference between a forward and a reverse reaction? I am studying Lechatelier's principal and it states that with an increase in temperature it favors a reverse reaction and when the temperature decreases it favors a forward reaction. What does this mean exactly?
Sunday, March 3, 2013 by Jaden

Chemistry
An equilibrium mixture contains 0.250 mol of each of the products (carbon dioxide and hydrogen gas) and 0.200 mol of each of the reactants (carbon monoxide and water vapor) in a 1.00-L container. CO(g) + H2O(g) <-> CO2(g)+ H2(g) How many moles of carbon dioxide would ...
Sunday, March 3, 2013 by qwerty

Chemistry
Phosphorus pentachloride decomposes according to the chemical equation PCl5(g) <-> PCl3(g)+Cl2(g) Kc=1.80 at 250 degrees Celsius A 0.222 mol sample of PCl5(g) is injected into an empty 3.25 L reaction vessel held at 250 °C. Calculate the concentrations of PCl5(g) and...
Sunday, March 3, 2013 by J

Chemistry
Can someone check my answers please? I had specific trouble with 7, 13, and 27 (I'm pretty sure my other answers are correct; some reassurance would be nice though). And I have a small question about 8. 1. The ΔHf of an element in its standard state is defined to be 0...
Sunday, March 3, 2013 by a Canadian

Chemistry
Consider the isomerization equlibria of an alkene (C4H8) that co-exists as three isomers. (These 3 are in an equlibrium triangle) Reaction 1: cis-2-butene ⇔ trans-2-butene Reaction 2: cis-2-butene ⇔ 2-methylpropene Reaction 3: trans-2-butene ⇔ 2-methylpropene...
Sunday, March 3, 2013 by Gleb

Chemistry
How many grams of carbon are in 4.30×1023 molecules of (C3H5)2S?
Sunday, March 3, 2013 by Hannah

chemistry
The specific heat of a certain type of metal is 0.128 J/(g·°C). What is the final temperature if 305 J of heat is added to 53.3 g of this metal initially at 20.0 °C?
Sunday, March 3, 2013 by Louis

chemistry
if a gallon of antifreeze weighs 8.75 pounds. what is the density of the antifreeze in g/ml?
Sunday, March 3, 2013 by cynthia

chemistry
C2H6 + O2 -> CO2 + H2O How many g of carbon dioxide are produced at the same time as 360g of water vapor in the burning of ethane
Sunday, March 3, 2013 by stephen

chemistry
Hey, I need help finding out how many moles of CO2 is produced from this reaction. Any help is appreciated, thanks. Mass of empty Erlenmeyer flask (g): 88.000 g Mass of Erlenmeyer flask and 20 mL H2SO4: 112.198 g Mass of 20 mL H2SO4: 24.198 g Trial I Mass of Na2CO3 added to ...
Sunday, March 3, 2013 by Matti

Chemistry
What is the pH at the equivalence point in the titration of 10.0 mL of 0.6 M HZ with 0.200 M NaOH? Ka = 7.0 × 10−6 for HZ.
Sunday, March 3, 2013 by Cate

Basic Chemistry (Science)
Determining Chemical Formulas? This was on my test a few days ago for Basic Chemistry, I received 8/20 and I'd really like to see how to work these problems out. *PLEASE SHOW WORK*. Their are four parts to this, If anyone could answer all four with easy explanations and ...
Sunday, March 3, 2013 by Chris

Chemistry
if the mole fractionof sulfuric acid (H2SO4) in an aqueous solitioin is 0.325, what is the percent by mass of H2SO4?
Sunday, March 3, 2013 by Joy

chemistry
0.5g of fuming h2s04 oleum is diluted with water. This solution is completely neutralized by 26.7ml of 0.4N naoh. Find the percentage of free s03 in the smaple solution. The answer 20.6% Assume that 50ml of 0.01M edta solution were added to 25ml of solution and the excess edta...
Sunday, March 3, 2013 by Fai

Chemistry
If you have 200ml of 25% aqueous solution of ethanol, what volume of ethanol and water are in the solution?
Sunday, March 3, 2013 by JD

Chemistry
what is the percent by mass of NaCHO3 in a solution containing 12g NaCHO3, dissolved in 450mL of water?
Sunday, March 3, 2013 by John

Chemistry
What is the mass of gas dissolved in a solution at 150kPa if 0.35g of the gas dissolves in 2.0L of water at 30kPa?
Sunday, March 3, 2013 by Jennifer

Chemistry
What is the expected mass of anhydrous salt formed after the waters of hydration of CoCl2·6H2O are driven off completely by heating, resulting in a mass loss of 2.000 g water?
Sunday, March 3, 2013 by Roxanne

chemistry
What volume (mL) of a 3.23 %w/v saline solution contains 69.1 mg of NaCl?
Sunday, March 3, 2013 by alex

Chemistry
Find the pH of a buffer that consists of 0.82 M methylamin (CH3NH2) and 0.71 M CH3NH3Cl (pKb of methylamine (CH3NH2) = 3.35.) I keep getting 3.41, but it says that it's wrong...
Sunday, March 3, 2013 by Edward

Chemistry
Calculate the pH of 0.215 M carbonic acid (H2CO3). (HINT: do NOT worry about the second H+ in this acid!) How would I solve this?
Sunday, March 3, 2013 by Edward

Chemistry
Sodium azide (NaN3) yields N2 gas when heated to 300 degrees Celsius , a reaction used in automobile airbags. If 1.00 mol of N2 has a volume of 47.0 liters under the reaction conditions , how many liters of gas can be formed by heating 35g of NaN3? The reaction is 2Nan3------&...
Sunday, March 3, 2013 by K

Chemistry
KClO3 dissociated in H20 should form a neutral solution. The results proved to be a slightly acidic solution with a pH of 6. What happened?
Saturday, March 2, 2013 by Misha

chemistry
You mix together in the proper manner the following VOLUMES: 0.0100 M Potassium iodide...9.2 mL 0.0010 M Sodium thiosulfate...6.5 mL Distilled water...16.8 mL 0.0400 M Potassium Bromate...13.9 mL 0.100 M Hydrochloric acid...6.1 mL Using the rate constant and rate equation ...
Saturday, March 2, 2013 by Cassie

Chemistry
How much energy is required to heat 36.9g of ice at 0 degrees celsius to water at 0 degrees celsius?
Saturday, March 2, 2013 by Maria

CHEMISTRY HELP PLEASE!!
0.350L of 0.160 M NH3 is added 0.140 L of 0.100 M MgCl2 . How many grams of (NH4)2SO4 should be present to prevent precipitation of Mg(OH)2 (aq) ? The Ksp of Mg(OH)2 is 1.8 x 10–11.
Saturday, March 2, 2013 by Marissa

CHEMISTRY HELP!
Calculate [Cu2+] in a 0.10 M CuSO4 (aq) solution that is also 6.4 M in free NH3 . Cu2+(aq) + 4NH3(aq) --->[Cu(NH3)4]2+ (aq) kf = 1.1 x 10^13
Saturday, March 2, 2013 by Leslie

Chemistry
How can I find the initial rate of formation of products {mol/((L)(s))}?
Saturday, March 2, 2013 by Zack

Chemistry
Suppose a can contains a residual amount of gas at a pressure of 755 mm Hg and a temperature of 25 °C. What would the pressure be if the can were heated to 1155 °C?
Saturday, March 2, 2013 by Amee

chemistry
If Kf = 1.86C/m, how many grams of calcium chloride must be added to 1.0L of water (assume a density of 1.0 g/mL) to lower the freezing point 4.0 C?
Saturday, March 2, 2013 by Dee

Chemistry
A solution contains 0.0273 M HNO3, 0.0302 M HI, and 0.320 M formic acid, HCOOH. What is the pH? A solution contains 0.160 M Ba(OH)2 (strong base) and 0.360 M ammonia, NH3 (weak base). What is the pH? I'm really not sure how to do this. I tried and got .443 and 12.91 ...
Saturday, March 2, 2013 by Anonymous

AP chemistry
what is the volume occupied by a mixture of 25.7 g of NO2 and 13.9g of SO2 at STP
Saturday, March 2, 2013 by Anonymous

chemistry
Determining Chemical Formulas? This was on my test a few days ago for Basic Chemistry, I received 8/20 and I'd really like to see how to work these problems out. *PLEASE SHOW WORK*. Their are four parts to this, If anyone could answer all four with easy explanations and ...
Saturday, March 2, 2013 by Chris

chemistry
How to convert centimeters into grams
Saturday, March 2, 2013 by Anonymous

Chemistry
I was given extra credit to find who Le Châtelier's High School Principal was. Not his PrincipLE, but his PrincipAL. My chemistry teacher told us only one student of his out of all these years came with the answer. Think outside of the box. Thanks.
Saturday, March 2, 2013 by Enrico

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