Monday
July 25, 2016

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Chemistry
If the heat of combustion for a specific compound is -1250.0 kJ/mol and its molar mass is 35.39 g/mol, how many grams of this compound must you burn to release 352.40 kJ of heat?
Monday, April 11, 2016 by Robert

Chemistry
For a particular isomer of C8H18, the following reaction produces 5104.1 kJ of heat per mole of C8H18(g) consumed, under standard conditions. (deltaH_rnx = -5104.1kJ) What is the standard enthalpy of formation of this isomer of C8H18(g)?
Monday, April 11, 2016 by Tiffany

Chemistry
In a constant-pressure calorimeter, 50.0 mL of 0.300 M Ba(OH)2 was added to 50.0 mL of 0.600 M HCl. The reaction caused the temperature of the solution to rise from 23.77 °C to 27.86 °C. If the solution has the same density and specific heat as water (1.00 g/mL and 4....
Monday, April 11, 2016 by Paul83

chemistry
magnessium chloride can be used to distinguish between cabonate and hydrogencarbonate ions. Describe how this is done with experimental observations
Monday, April 11, 2016 by jay

chemistry
magnessium chloride can be used to distinquish between cabonate and hydrogencarbonate ions. Descrbe how this done with experimental observations
Monday, April 11, 2016 by jay

Chemistry
What is and isotope pair?
Monday, April 11, 2016 by Bethany

Chemistry
If you had .1 ml in a 1M solution of HCl how much water would you need to dilute it to a pH of 7?
Monday, April 11, 2016 by Sabrina

chemistry
How many joules of heat are required to completely covert 95.0 grams of water to steam?
Monday, April 11, 2016 by Sandrine

chemistry
How many joules of heat are removed to completely covert 70.0 grams of water to ice at zero Celcius?
Monday, April 11, 2016 by Tammy

Chemistry
calculate the % dissociation of a 0.750M acetic acid solution and 0.50 M sodium acetate solution. I got the % for acetic acid to be 0.48% but cant finish the question.
Sunday, April 10, 2016 by Meaghan

organic chemistry
This is for a phase catalysis lab experiment 1. How is the phase transfer catalyst removed from the product? I said, by washing it with salt. 2. what purpose does washing with 15% (half-saturated) NaCl solution serve? I said, to remove bulk of water 3. There is a slight excess...
Sunday, April 10, 2016 by tols

Chemistry
If the percent yeild of the following equation is 55%, how many grams of H2SO4 are produced when 4.88 x 10^24 molecules of SO3 are combined with excess water? SO3(g)+H2O(l)->H2SO4(aq). what would be the formula to solve this equation
Sunday, April 10, 2016 by Sean

chemistry redox reactions
can someone check my labels for the reaction of a radical with an extra electron, (R(e-)) and an antioxidant, ArOH. R(e-) + ArOh --> RH + ArO(e-) R(e-) is oxidizing agent. ArOH is reducing agent. RH is reduced ArO(e-) is oxidized. Is this correct? And the other possible ...
Sunday, April 10, 2016 by Anonymous

Chemistry
In the equation 2 NaN3----2 Na + 3 N2// how much N2 would be produced if 100 grams of NaN2 completely reacted at STP?
Sunday, April 10, 2016 by Lisa

Chemistry
Make NaCl from NaHCO3 and HCl-Starting with 3.0 grams of NaHCO3-what would be a source of error on yield of purity of NaCl and what modifications could be made?
Sunday, April 10, 2016 by Lisa

Chemistry
What volume of 1.0 M NaOH must be added to 1.5 L of 1.20 M CH3COOH (ka=1.8x10^-5) to make the solution a buffer for pH 4.50? I do not understand how to determine the mols of NaOH. I tried to use the equation where: [H3O+] = ka (nHA/nA-) but it is not giving me the correct ...
Sunday, April 10, 2016 by Charles

Chemistry: Salt of weak acids and bases
If 25 mL of 0.20M NaOH is added to 20 mL of 0.25M boric acid, what is the pH of the resultant solution?
Sunday, April 10, 2016 by Wen

Chemistry
How many grams of pure uranium can theoretically be extracted from a 10.0 kg sample of pitchblende, which is 92.0% UO2? Im not looking for the answer. I would just like to know the formula to solve the problem.
Saturday, April 9, 2016 by Sean

Chemistry
Sulfur dioxide (SO2) reacts with oxygen gas to make sulfur trioxide (SO3). How many grams of oxygen are used to produce 8.11 grams of sulfur trioxide?
Saturday, April 9, 2016 by Petey

Limiting Reactant (Chemistry)
What is the limiting reactant for the following reaction if there are 3.4 moles of Ca(NO2)2 and 2.4 moles of Li3PO4? 3Ca(NO2)2 + 2Li3PO4 --> 6LiNO2 + Ca3(PO4)2 A)Ca(NO2)2 B) Li3PO4 C) LiNO2 D) Ca3(PO4)2
Saturday, April 9, 2016 by Petey

Chemistry
For the following reaction: Fe2O3 + 3CO --> 2Fe + 3CO2 how many grams of Fe2O3 is needed to produce 111 g of Fe? A) 79.3 g Fe2O3 B) 159 g Fe2O3 C) 317 g Fe2O3 D) 71.4 g Fe2O3
Saturday, April 9, 2016 by Petey

Chemistry / Stoichiometry
When 1 mol of CH4 is burned, 490 kJ of energy are released as heat. CH4 + O2 -> 2H2 + CO2 If 3.2g of CH4 are burned, what is the value of the heat of the reaction? The answer worked in class was -180 kJ, but while I was redoing problems, I got the answer 98 kJ (both ...
Saturday, April 9, 2016 by Caitlyn

Chemistry
Aqueous sulfuric acid H2SO4 will react with solid sodium hydroxide NaOH to produce aqueous sodium sulfate Na2SO4 and liquid water H2O . Suppose 31. g of sulfuric acid is mixed with 11.5 g of sodium hydroxide. Calculate the maximum mass of sodium sulfate that could be produced ...
Saturday, April 9, 2016 by Tre

chemistry
How many moles of gas must be forced into a 5.0 L tire to give it a gauge pressure of 33.6 psi at 28 ∘C? The gauge pressure is relative to atmospheric pressure. Assume that atmospheric pressure is 14.8 psi so that the total pressure in the tire is 48.4 psi . PV = nRT 48....
Saturday, April 9, 2016 by Tammy

Chemistry
Iron metal reacts with oxygen gas to produce iron(III) oxide. If you have 12.0 moles of iron, for complete reaction you need: (HINT you need the balanced chemical reaction!) A) 9.0 moles of O2 and produce 3.0 moles of Fe2O3 B) 9.0 moles of O2 and produce 6.0 moles of Fe2O3
Saturday, April 9, 2016 by Petey

Chemistry
How much water would be formed if 3.00 mol NH3 reacted with excess oxygen gas in the following equation? Given the reaction 4NH3+ 5O2 --> 4NO + 6H2O A) 2.00 mol B) 3.00 mol C) 4.50 mol D) 6.00 mol E) None of these
Saturday, April 9, 2016 by Petey

Chemistry
Propane gas is stored in a tank at a pressure of 15.0 atm at 22.0 °C. The tank can hold a pressure of 42.0 atm before bursting. During a fire the gas is heated to 600.0 °C. What is the gas pressure, and will the tank contain the gas without bursting? I know the ...
Saturday, April 9, 2016 by Drew

chemistry redox
can someone check my labels for the reaction of a radical with an extra electron, (R(e-)) and an antioxidant, ArOH. R(e-) + ArOh --> RH + ArO(e-) R(e-) is oxidizing agent. ArOH is reducing agent. RH is reduced ArO(e-) is oxidized. Is this correct? And the other possible ...
Saturday, April 9, 2016 by check my work :)

Chemistry
Question: write the balanced equations for the titration of oxalic acid (C2H2O4) with KOH. Work so far: I know that the overall equation is COOH)2 + 2KOH ------.> (COOK)2 + 2H2O but I am unsure how to proceed to the two step-wise equations
Saturday, April 9, 2016 by Alexa

Analytical chemistry
an 0.5031 gram sample of iron ore is determined through redox titration using K2Cr2O7. The sample was dissolved in HCl and all the iron was converted to the 2+ state. Titration to the endpoint required 24.34 mL of 0.01887 mol/L K2Cr2O7. Calculate the amount of Fe2O3 as a ...
Saturday, April 9, 2016 by Sam

Chemistry
what mass of hydrogen chloride gas is required to produce 250 ml of hydrochloric acid solution with a pH of 1.57
Saturday, April 9, 2016 by John

chemistry
in a liquid mixture 3 mols of component A is mixed with 2 mols of component B the activity coefficient of component A is 0.75. for a temp at 365 K determine the chemical potential of A in the mixture. chemical potential of component A in its pure state is 48.5 KJ/mol
Saturday, April 9, 2016 by saanvi

Chemistry
What is the yield of the synthesis of ammonia to 400° C and 500 atm of pressure?
Saturday, April 9, 2016 by Sabrina

Chemistry
As an eager scientist on a hot summer day you wish to determine how much ice to buy to add to your cooler which is filled with 4.0 × 101 cans of soda which are warm at 82.9°F. Each can has a mass of 378 g and ideally you want the temperature of the drinks to be 40.1&...
Saturday, April 9, 2016 by Spencer

Chemistry
what mass of hydrogen chloride gas is required to produce 250 ml of hydrochloric acid solution with a pH of 1.57 pH 1.57 H3O = 10^-1.57= .027mol/L .027(4)= .108mol/L 36.46(.108)=3.9g
Friday, April 8, 2016 by John

Chemistry
Radium-223 has a half-life of 11.4 days.Approximately how long would it take for the activity of a sample of 223Ra to decrease to 2.00 % of its initial value?
Friday, April 8, 2016 by Josh

Chemistry
If it takes 45 days for 80.0 mg of a particular radioactive isotope to decay to 10.0 mg what is its half-life?
Friday, April 8, 2016 by Josh

Chemistry
A radionuclide undergoes alpha emission, and thorium-234 is produced. What was the original radionuclide?
Friday, April 8, 2016 by Josh

Chemistry
Radium-223 nuclei usually decay by alpha emission. Once in every billion decays, a radium-223 nucleus emits a carbon-14 nucleus. Write a balanced nuclear equation for alpha emission. Write a balanced nuclear equation for carbon-14 emission.
Friday, April 8, 2016 by Josh

Chemistry
A Partially weather balloon has a volume of 195 L at a pressure of 0.993 atm. What will be the pressure in the balloon when it is inflated to a volume of 7500 L? (assume to temp. change)
Friday, April 8, 2016 by Sean

Science
A chemistry teacher needs to prepare 750 ml of a 2.5M solution of Potassium iodide for a lab. How many grams of potassium iodide will be needed to make the solution?
Friday, April 8, 2016 by Ane

Chemistry
Combine the Ksp and Kf equilibria for AgCl and Ag(NH3)2+ respectively and demonstrate Hess's law to determine the equilibrium constant for the dissolution of AgCl in NH3. AgCl + 2NH3 --> Ag(NH3)2 + Cl- K= (Ksp)(Kf) If there is only one mole of both AgCl and Ag(NH3)2, ...
Friday, April 8, 2016 by Kaitlin

Chemistry
A Balloon is inflated to 1.78 L inside a store that has its air conditioner set to 20 C What volume must the balloon be able to hold so as not to burst when it is taken outside into the 32 C summer heat?
Friday, April 8, 2016 by Tory

Chemistry
If a Gas occupies 200.0 Ml at 400 k, what volume wiall it occupy at 400 K?
Friday, April 8, 2016 by Tory

chemistry
1.how to prepare a)200ml of a 4MHCl? b)100ml of a 1.5NaOH?
Friday, April 8, 2016 by kanika

Chemistry
Why is the equivalence point pH of the HCl-TRIS titration = 4.6?
Friday, April 8, 2016 by Jeff

Chemistry
How do you prepare one liter of phosphate buffer 0.01 M at pH 12.0 from 85% phosphoric acid (density 1.69g/ml) and NaOH 1.0 M
Thursday, April 7, 2016 by Phil

Chemistry please help!
The reaction through which carbon changes from graphite to diamond form is represented by the equation C(graphite) ---> C(diamond) delta H: ? Using the reactions below, determine the amount of heat absorbed in the change of one mole of graphite to one mole of diamond C(...
Thursday, April 7, 2016 by Rose

chemistry
A nickel is about 2 millimeter thick or 2/1000 of a meter. How many nanometers is this?
Thursday, April 7, 2016 by Tom S

chemistry
In the lab, you mix 30mL of 0.30M Na2SO4 with 10mL of 0.25M Ba(OH)2 to produce BaSO4 and NaOH. Calculate the theoretical yield (in moles) of BaSO4 produced from this reaction. State your answer in decimal form and round to two sig. fig. (not scientific notation).
Thursday, April 7, 2016 by Liyah

Chemistry
Calculate the amount of water you need to add (in mL) to 30mL of 1.5M HCl to dilute it to a concentration of 1.25M.
Thursday, April 7, 2016 by Liyah

chemistry
What is the molarity of the following solutions? A. 0.96 g MgCl2 in 500 mL solution B. 9.33 g Na2S in 450 mL solution C. 2.48 g CaF2 in 375 mL solution
Thursday, April 7, 2016 by justin

Chemistry
In 2006, Soviet dissident Alexander Litvinenko was murdered when Polonium-210 was added to his tea; he died three weeks later. Polonium-210 is an alpha emitter. What other product is formed?
Thursday, April 7, 2016 by Jessie

Chemistry
Radium-223 nuclei usually decay by alpha emission. Once in every billion decays, a radium-223 nucleus emits a carbon-14 nucleus. Write a balanced nuclear equation for alpha emission. Write a balanced nuclear equation for carbon-14 emission.
Thursday, April 7, 2016 by mark

chemistry
A radionuclide undergoes alpha emission, and thorium-234 is produced. What was the original radionuclide?
Thursday, April 7, 2016 by chris

chemistry
Fluorine-20 has a half-life of 11.0 s. If a sample initially contains 49.0 μg of this isotope, how much remains after 66.0 s ?
Thursday, April 7, 2016 by susan

Chemistry
If it takes 45 days for 80.0 mg of a particular radioactive isotope to decay to 10.0 mg what is its half-life?
Thursday, April 7, 2016 by Kelly

Chemistry
Radium-223 has a half-life of 11.4 days. Approximately how long would it take for the activity of a sample of 223Ra to decrease to 2.00 % of its initial value?
Thursday, April 7, 2016 by sierra

Chemistry
Cells use the hydrolysis of adenosine triphosphate (aTP) as a source of energy. This reaction can be written as, ATP(aq) + H2O(l) --> ADP(aq) + H2PO4-(aq), wehre ADP represents adenosine diphosphate. For this reaction, Delta Grxn = -30.5KJ/mol. If all the free energy from ...
Thursday, April 7, 2016 by Anonymous

Chemistry
Both ethanol (CH3CH2OH, MM=46.07g/mol) and methanol (CH3OH, MM=32.04g/mol) have been considered as fuels for automobiles. Which is the better fuel, on a per gram basis, when burned with oxygen? CH3CH2OH(g) DeltaHf(KJ/molrxn) = -235.10 H3OH (g) DeltaHf(KJ/molrxn) = -200.66 H2O...
Thursday, April 7, 2016 by Sarah

chemistry
In Europe, gasoline efficiency is measured in km/L. If your car's gas mileage is 27.0 mi/gal , how many liters of gasoline would you need to buy to complete a 142-km trip in Europe? Use the following conversions: 1km=0.6214mi and 1gal=3.78L.
Thursday, April 7, 2016 by Anonymous

Chemistry
How many gallons of water at 70 deg. F is required to cool a gallon of water at 212 deg f?
Thursday, April 7, 2016 by Fritz

Chemistry
A saline solution with a mass of 400 g has 30 g of NaCl dissolved in it. What is the mass/mass percent concentration of the solution?
Thursday, April 7, 2016 by Sabrina

Chemistry
A ground state hydrogen atom absorbs a photon of light having a wavelength of 93.03 nm. It then gives off a photon having a wavelength of 1005 nm. What is the final state of the hydrogen atom? What is the equation to solve this?
Thursday, April 7, 2016 by Emma

Chemistry
What is the mole fraction of NaBr in an aqueous solution that contains 20.1% NaBr (weight/weight%)?
Thursday, April 7, 2016 by Steve

chemistry
How much energy is obtained if 11.2g of hydrogen gas are allowed to react with excess fluorine? H2 (g) + F2 (g)--- 2HF (g) + 124kcal
Thursday, April 7, 2016 by angie

Chemistry
A chemist reacted 0.05 moles of sodium with water to form 50cm3 of sodium hydroxide solution. Na + H2O -- NaOH + H2 (unbalanced) What mass of sodium was reacted?
Thursday, April 7, 2016 by Jo

Chemistry
What is the [H3O+] of a solution if its pH = 8.26?
Thursday, April 7, 2016 by Emma

Chemistry
15.0 ml of 0.50 M NaOH is added to a 100.-mL sample of 0.442 M NH3 (kb for NH3= 1.8 x 10^-5). What is the equilibrium concentration of NH4+ ions?
Thursday, April 7, 2016 by Aisha

Chemistry please help
The reaction through which carbon changes from graphite to diamond form is represented by the equation C(graphite) ---> C(diamond) delta H: ? Using the reactions below, determine the amount of heat absorbed in the change of one mole of graphite to one mole of diamond C(...
Thursday, April 7, 2016 by Rose

chemistry
what is the molarity of the solution comtaining 2.5g of acetic acid in 75g of benzene
Thursday, April 7, 2016 by saira

Chemistry
Acid in vinegar has pka value of 1.85 x 10^-5 at 25oC find the pkb value of its conjugate base?
Thursday, April 7, 2016 by Ahmad

chemistry
How do I prepare 100mL of 10g/L HCl from concentrated HCl(37%HCl, density 1.19g/mL) Is it 2.28mL of conc HCl dilute to 100mL with water? Please show the calculation steps.
Thursday, April 7, 2016 by haji

Chemistry
A sample has a molar mass of 162g/mol. When a sample of mass 0.385g was burned , 1.072g of CO2 ,0.307g H2O and 0.068g of nitrogen were produced. What is empirial and molecular formular of a sample . Write equation for combustion
Thursday, April 7, 2016 by Marie

chemistry
the solubility of CaF in water is 7*10^-2 gm/l. find its solubility in 0.5m CaCl2 soln
Thursday, April 7, 2016 by s

Chemistry
what volume of 1.00M ca(oh)2 is needed to neutralize 250.0mL of 0.100M HCL?
Wednesday, April 6, 2016 by Sierra

Chemistry of Life Science
1. In the introduction to this experiment, it states that you reacted 2.5 grams of salicylic acid with an excess of acetic anhydride, meaning that there would be a higher number of moles of acetic anhydride then salicylic acid, proportionally. Assuming the density of acetic ...
Wednesday, April 6, 2016 by Tracy

chemistry
what is the approximate volume of gas in a 1.50 mol sample that exerts a pressure of 0.922 atm and has a temp of 10.0°C?
Wednesday, April 6, 2016 by jackson

chemistry
A sample of gas at 42°C has a volume of 5.2 L and exerts a pressure of 1.00 atm. How many moles of gas are in the sample?
Wednesday, April 6, 2016 by jackson

Chemistry
Write the dissociation equation for calcium chloride. Include a diagram of the resulting solution.
Wednesday, April 6, 2016 by Jade

Chemistry
A sample has a molar mass of 162g/mol. When a sample of mass 0.385g was burned , 1.072g of CO2 ,0.307g H2O and 0.068g of nitrogen were produced. What is empirial and molecular formular of a sample . Write equation for combustion
Wednesday, April 6, 2016 by Marie

Chemistry
Consider the titration of 50mL of 2.0M HNO3 with 1.0M KOH. At eah step, add the following: 0ml, 25ml, 50ml. a) Write a reaction to show the initial reaction b)ICE table c) determine the spectators present after d)Calculate the pH
Wednesday, April 6, 2016 by Gub

Chemistry
For the H 3 CNCO molecule, (Note: The atoms are bonded in the order CNCO, with the three H atoms bonded to the first carbon atom.) answer the following questions. What is the ideal H-C-H bond angle? (0, 30, 45, 60, 90, 109, 120, 145, or 180.) What is the ideal N-C-O bond angle...
Wednesday, April 6, 2016 by Anonymous

Chemistry
The following Chemical reaction produces a precipitate in an aqueous solution. NaOH(aq)+Mg(Cl)2(aq)<->NaCl(aq)+Mg​(OH)2(s) With an equilibrium constant of K=1.3. If NaOH and Mg(Cl)2 are added in stoiciometric ratio and 1.20 mol of NaOH are present at Equilibrium, ...
Wednesday, April 6, 2016 by Bryce

Chemistry
Calculate the enthalpy of formation of maganese (IV) oxide based on the following information. 4Al(s) + 3MnO2(s) --> 3Mn(s) + 2Al2O3(s) Delta H = -1790 kJ 2Al(s) + 3/2O2 (g) ---> Al2O3 (s) Delta Hf = -1676 kJ
Wednesday, April 6, 2016 by Rose

chemistry
Highlights the basic points in lewis and langmuir theory of electrovalency.
Wednesday, April 6, 2016 by Yamkela Tshisa

Chemistry
Complete the following equilibrium reactions that are pertinent to an aqueous solution of Ag2CO3. Physical states, s, l, g, and aq, are optional. So far I worked it out to be: Ag2CO3(s) <--> 2Ag^+ + CO3^(2-) H2CO3(aq) + H2O(l) <--> H3O^(1+) + (HCO3)^(-) HCO3^(-)(aq...
Wednesday, April 6, 2016 by Craig

chemistry
what increasing order of dipole moment among nitrobenzene methylbenzene phenol and toluene
Wednesday, April 6, 2016 by rohit

Chemistry
Identify the following as either reduction or oxidation: a. 2I^- -> I2 + 2e- (my answer oxidized) b. Zn2+ + 2e^- -> Zn (reduced) could someone check my answers? I remember OIL RIG (oxidation is loss, reduction is gain.) but I'm still uncertain of what I answered.
Wednesday, April 6, 2016 by bubble dragon

chemistry
how can we produce ethane from methane?
Wednesday, April 6, 2016 by tasnuba

Chemistry
Oxalic acid & phosphoric acid are polyprotic acid. For both acids, provide the equilibrium reactions showing all of the dissociation steps and the expressions for each acid dissociation constans.
Wednesday, April 6, 2016 by Ziera

college chemistry
calculate the equilibrium constant for the following reaction at 298k given that DeltaGrxn=2.8kj/mol N2O4-2NO2 I thought to get K you use the expression K=e^(-deltaG/(RT)) but I cant get the same answer my professor put down which is 3.1
Wednesday, April 6, 2016 by Jeremy

chemistry
If 5.40 kcal of heat is added to 1.00 kg of water at 100⁰C, how much steam at 100⁰C is produced? Show all calculations leading to an answer. Please help?
Wednesday, April 6, 2016 by emily

chemistry
You have two sealed jars of water at the same temperature. In the first jar there is a large amount of water. In the second jar there is a small amount of water. Using 3 -4 sentences explain how the vapor pressure of water in the first jar compares with the vapor pressure of ...
Wednesday, April 6, 2016 by emily

chemistry
What volume of a oxygen at STP was collected? oxygen gas is collected over water at a temperaturee of 10 degrees C and a pressure 1.2 atm. The volume of gas plus water vapor collected is 293ml.
Wednesday, April 6, 2016 by dee

chemistry
Why is it important to use the same pipet through out the experiment?
Wednesday, April 6, 2016 by Jimmy

science:chemistry
magnesium trioxocarbonate (IV) decomposed according to the equation MgCO3(s) -MgO2(s) + CO2(g).if 6.0g of magnesium trioxocarbonate (IV) is completely decomposed ,calculate :i. the mass of carbon (IV) oxide produced
Wednesday, April 6, 2016 by michael

Chemistry
Potassium oxide reacts with water to produce of potassium hydroxide. Please provide a balanced equation, and determine how much potassium oxide is needed to produce 80.5g of potassium hydroxide?
Tuesday, April 5, 2016 by Nicole

high school chemistry
You are going to titrate 20 mL of .10M HCL with 0.10M NaOH. What is the pH at the equivalence point. How do I figure out the equivalence point when I have already figured out that the initial pH of the HCL and NaOH are both 1?
Tuesday, April 5, 2016 by Jerome

Chemistry
How many mole of fe2o3 will be formed?
Tuesday, April 5, 2016 by Daniel Miller

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