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March 28, 2015

Search: Calculate the enthalpy for

Number of results: 20,122

To Ms. Sue
How do I calculate how much grain is required to feed you through the chicken you ate for dinner? And is it necessary to really try and calculate it?
July 14, 2009 by devon

Chemistry
Commercial vinegar usually has a concentration of 5%, per volume. a) Calculate the [H3O+] , if the density of acetic acid is 1.051 g/mL. b) Calculate the pH.
May 13, 2012 by Andrea

physics
a jet plane traveling at +87 m/s lands on a runway and comes to ret in 11 s. a)Calculate its uniform acceleration b)Calculate the distance it travels
November 6, 2012 by charlie

physics
a jet plane traveling at +87 m/s lands on a runway and comes to rest in 11 s. a)Calculate its uniform acceleration b)Calculate the distance it travels
November 6, 2012 by kayla

Chemistry
In the titration of 20.00 mL of 0.175 M NaOH, calculate the number of milliliters of 0.200 M HCl that must be added to reach a pH of 12,55. I know the answer is 11,9 mL but I don't know how to calculate it.
November 22, 2013 by Helga

physics
The system is frictionless and the trolley accelerates to the left at 3m/s squared. (a) calculate the unknown mass M. (b) calculate the magnitude of the forces in each string.
March 15, 2015 by kulani

chemistry
Given the following reactions Fe2O3(s) + 3CO (s) → 2Fe (s) + 3CO2(g)ΔH =-28.0 kJ 3Fe (s) + 4CO2(s) → 4CO (g) +Fe3O4(s) ΔH = +12.5 kJ the enthalpy of the reaction of Fe2O3 with CO 3Fe2O3(s) + CO (g) → CO2(g) + 2Fe3O4(s) is __________ kJ
November 2, 2014 by Anonymous

chemistry
Calculate ∆T for the reaction. Assume the initial temperature of both reactants is 25.0◦C. Calculate the volume of the reaction mixture. Calculate the mass of the reaction mixture. Assume the density of the mixture is 1.03 g mL^(-1). Calculate the heat transferred ...
October 22, 2014 by Anonymous

physics
For a helium atom containing two protons, two neutrons and two electrons: A)Calculate the first energy levels(n=1,2,3,4,5)(answers (-54.4eV, -6.04eV, -3.4eV, -2.176eV) b)Calculate the frequency in Hz of a proton emitted from n=2 to n=1 (answer 9.86x 10^15Hz) c)calculate the ...
December 4, 2012 by chanty

Enthalpy of Formation
N2H4(g) + H2(g)--> 2 NH3(g) H1 = 1876kJ 3 H2(g) + N2(g)--> 2 NH3(g) H2 = 922 kJ The H.f for the formation of hydrazine: 2 H2(g) + N2(g)--> N2H4(g) will be______kj/mol I am very confused here. I thought I would just add H1 and H2 and divide by the molar mass of N2H4...
May 16, 2010 by CHem

chemistry
CH3OH  CO + 2H2 H = +90.7kJ 9. For the forward reaction, is heat being absorbed or released? 10. How much heat would be transferred if 45.0 g of CH3OH is decomposed? 11. What quantity of CH3OH decomposition would lead to an enthalpy change of 18.5 kJ
May 11, 2011 by Anonymous

chemistry
CH3OH  CO + 2H2 H = +90.7kJ 9. For the forward reaction, is heat being absorbed or released? 10. How much heat would be transferred if 45.0 g of CH3OH is decomposed? 11. What quantity of CH3OH decomposition would lead to an enthalpy change of 18.5 kJ
May 11, 2011 by Anonymous

Chemistry
Pentane is a small liquid hydrocarbon, between propane and gasoline in size C5H12. The density of pentane is 0.626g/ml and its enthalpy of combustion is ΔHcomb =-3535kj/mol. Estimate the fuel valve and the fuel density of pentane.
November 8, 2012 by Brittany

chemistry
The reaction SO2 + H2O =H2SO4 Is the last step in the commercial production of sulfuric acid . the enthalpy change for this reaction is -227 KJ . In designing a sulfuric acid plant is it necessary to provide for heating or cooling of the reaction mixture ? explain
November 12, 2014 by mathew

Thermochemistry
A constant pressure calorimeter having a heat capacity of 60.8 kJ/K is used to measure the energy released from burning a compound in excess oxygen to form CO2(g) and H2O(l). If the enthalpy of combustion of the compound is -2914.0 kJ/mol and the temperature of the calorimeter...
December 4, 2011 by LaurenB

Chemistry
A zinc-copper battery is constructed as follows at 25C. Zn|Zn^2+ (0.15 M)||Cu2+(3.00 M)|Cu The mass of each electrode is 200. g. a) Calculate the cell potential when this battery is first connected. - i got this to be 1.14V b.) Calculate the cell potential after 10.0 A of ...
April 28, 2011 by Pamela

Lauren
The amount of heat required to raise temperature of 55.85 g of iron 1 degrees C is called its A. Change of energy B. Enthalpy C. Molar heat capacity D. Specific heat capacity E. Specific Heat.
November 16, 2007 by Chemistry

Chemistry
Calculate the pH of a 50.0 mL solution 0.0120 M ethylaminium chloride (C2H5NH3Cl ) and 0.0360 M ethylamine C2H5NH2. Kb = 4.3 x 10-4 Calculate the pH when 5.0 mL of 0.1 M HI is added. Ignore any changes in the volume
April 17, 2013 by m

Chemistry
I have two questions that I do not know how to answer. Thanks for your help! 1. Calculate the [OH^-], [H^+], pH, and pOH for a 0.50M solution of CN^- 2. Calculate the molar solubility of PbCl2 in 0.40M KCl
January 11, 2015 by Liz

Chemistry
Indicate whether Delta S and Delta H is positive or negative. Then indicate if the reaction is entropy driven, enthalpy driven or neither. NaCl(s) + H2O(l) + Heat => NaCl (aq)
September 19, 2008 by Yuval

UCF
What will be the change in enthalpy when 100.0 g of butane, C4H10, is burned in oxygen as shown in the thermochemical equation below? 2 C4H10(l) + 13 O2(g) → 8 CO2(g) + 10 H2O(g) ΔH = −5271 kJ −2636 kJ −4534 kJ −9087 kJ −1.817 104 kJ
April 2, 2014 by Alex

physics university
For a helium atom containing two protons, two neutrons and two electrons: A)Calculate the first energy levels(n=1,2,3,4,5)(answers (-54.4eV, -6.04eV, -3.4eV, -2.176eV) b)Calculate the frequency in Hz of a proton emitted from n=2 to n=1 (answer 9.86x 10^15Hz) c)calculate the ...
December 3, 2012 by chanty

Thermodynamics
A turbine operating under steady flow conditions receives steam at the following state: pressure 13.8 bar, specific volume 0.143 m^3/kg, specific internal energy 2591kJ/kg and velocity 30m/s. The state of steam leaving the turbine is as follows: pressure 0.35 bar, specific ...
June 3, 2010 by Claire

HOW TO CALCULATE LASS WIDTHS?
can someone tell me how to calculate class width. suppose the number of classes and class widh being 5 and 12 respectively.form a grouped frequency distribution.. the maximum is 98 while the minimum is 12. Should i calculate it: maximum - minimum that is 98-12=76 to know how ...
April 22, 2012 by PALLAVI

college chemistry
the normal freezing point of the element mercury, Hg(l), is a -38.9C and its molar enthalpy of fusion, ΔHfusion=2.29 KJ/mol. What is the entropy change (J/K) of the system when 50 g of Hg(l) freezes at the normal freezing point. Hg= 200.59 g/mol
December 6, 2010 by Jamaal

Chemistry
Substance A has a normal fusion point of ‑10.0 oC, an enthalpy of fusion = 150.0 J g^-1; specific heats for the solid and the liquid are 3.00 and 6.20 J g^-1 oC^-1, respectively. How much heat, in J, is required to change 150 grams of A from a solid at 40.0 oC to a ...
November 8, 2011 by Kale

chemistry
Ethanol (C2H5OH) melts at -114 C. The enthalpy of fusion is 5.02 kJ/mol. The specific heats of solid and liquid ethanol are 0.97 J/g-K and 2.3 J/g-K, respectively. How much heat (kJ) is needed to convert 25.0 g of solid ethanol at -135 C to liquid ethanol at -50 C?
February 3, 2012 by Anonymous

Chemistry
Determine how many mL of solution A (acetic acid-indicator solution) must be added to solution B (sodium acetate-indicator solution) to obtain a buffer solution that is equimolar in acetate and acetic acid. Solution A: 10.0 mL 3.0e-4M bromescol green solution 25.0mL 1.60M ...
October 29, 2012 by Jake

Chemistry
Consider the following two thermochemical equations N2+2.5O2-> N2O5(s) Delta H=xkJ N2+2.5O2-> N2O5(g) Delta H=ykJ The enthalpy change in kJ for the sublimation of one mole of N205 solid to gas would be represented by the quantity a)x+y b)x-y c)y-x d)-x-y I am thinking it...
July 25, 2010 by Bobz

Chemistry
Neat pure ethanol C2H5OH has an enthalpy of vaporization of 39.3 Kj/mol, and a vapor pressure of 0.308 atm at 50 C. What is the boiling point, at atmospheric pressure of 1 atm, of a solution consisting of 35 G of phenol (a non-electrolyte hydrocarbon with a molecular formula ...
April 30, 2012 by Mima

chemistry
The enthalpy change for the reaction below at 25oC is -2,252 kJ (per mole of C11H24). What is the internal energy change for the reaction at 25oC? 11 CO(g) + 23 H2(g) --> C11H24(l) + 11 H2O(l)
November 3, 2014 by Sasha

Physics
A 125 kg fullback is running at 5.0 m/s to the east and is stopped in 0.75 s by a head-on tackle by a tackler running due west. a) Calculate the original momentum of the fullback. i did this and got 625 kg- m/s b) Calculate the impulse exerted on the fullback i did this and ...
October 31, 2009 by Jen

chemistry
Can one calculate the number of moles of air? If so, calculate the number of moles in 1 kg of air (making sure your calculation, units and assumptions are fully explained); If not, explain why it is not possible to calculate the number of moles of air.
August 7, 2013 by sarah

CHEMISTRY
A mixture contains 5.00 g each of O2, N2, CO2, and Ne gas. Calculate the volume of this mixture at STP. Calculate the partial pressure of each gas in the mixture at STP. How do you calculate the mole fraction of each gas?
May 11, 2010 by ~anonymous

chem
assuming you have o.4g of Y(OH)3, calculate the mass of BaO2 required to react stoichiometrically to produce YBa2Cu3O7. Now calculate the mass of CuO. Please HELP! Write the balanced equation. Then, calculate the moles of Y hydroxide from .4 g. Then, notice from the balanced ...
October 24, 2006 by nick

Chemistry
The vapor pressure of the liquid HF is measured at different temperatures. The following vapor pressure data are obtained. Temperature(K) Pressure mmHg 250 129.63 260 206.65 270 318.22 280 475.16 Determine the enthalpy of vaporization. I have know idea how to start this. Thank...
February 7, 2012 by Hannah

Chemistry
A 5.0g KBr sample, at 25 degrees celsius, dissolved in 25 ml of water, also at 25 degrees celsius. the final equilibrium temperature of the resulting solution is 18.1 degrees celsius, What is the enthalpy change in J/g and KJ/mole of KBr.
November 14, 2012 by jonathan

Chemistry
A titration is performed by adding .600 M KOH to 40.0 mL of .800 M HCl. Calculate the pH before addition of any KOH. Calculate the pH after the addition of 5.0 mL of the base. Calculate the volume of base needed to reach the equivalence point. What is the pH at the equivalence...
April 1, 2011 by Summer

Chemistry
A 5.0-g Sample of KBr at 25.0 degrees celsius dissolves 25.0 mL of water also at 25.0 degrees celsius. The final equilibrium temperature of the resulting soltution is 18.1 degrees celsius. What is the enthalpy of of solution in kilojoules per mole of KBr?
March 20, 2013 by Sam

Chem 2 enthalpy
How much heat is evolved when 25.5 g of benzene freezes at 5.5 Celcius (molar heat of fusion is 9.94 kJ/mol and molar mass of benzene= 78.0 g/mol)
August 26, 2010 by Anonymous

Thermochemistry
When 1.477 mole of an inorganic salt were dissolved in 1.00 L of water in a constant pressure solution calorimeter, the temperature of the calorimeter changed from 25.00oC to 24.40 oC. The total heat capacity of the calorimeter including all its contents was 2.18 kJ oC-1 What ...
June 12, 2009 by Douglas

Chemistry - General, Hess's Law
In an experiment, 11.6g of a salt was dissolved in 100.0ml of water contained in the above calorimeter, all at an initial tmperature of 24.5 degrees Celsius. After dissolution was complete, the temperatur was 31.8C. The specific heat of the solution is 3.63J/gxC and the ...
July 24, 2009 by Sahar

apchem
A 15.0g sample of liquid ethanol, C2H5OH, absorbs 5.13x10^3 J of heat at its normal boiling point, 78.0C. The molar enthalpy of vaporization of ethanol is 39.3kJ/mol. (a) What volume of ethanol vapor is produced? The voume is measured at 78.0C and 1.00atm pressure. (b) What ...
January 27, 2008 by alk

Chemistry
A 15.0g sample of liquid ethanol, C2H5OH, absorbs 5.13x10^3 J of heat at its normal boiling point, 78.0C. The molar enthalpy of vaporization of ethanol is 39.3kJ/mol. (a) What volume of ethanol vapor is produced? The voume is measured at 78.0C and 1.00atm pressure. (b) What ...
January 27, 2008 by David

Chemistry
The net reaction for fusion on a star like our Sun is: 4H(1,1) ==> He(4,2) + 2e(0,+1) Calculate the mass defect for this reaction. If one atom of He is formed this way, calculate the energy released. If one Kg of He is formed, calculate the energy released. The masses of ...
March 16, 2014 by Jay

Inorganic chemistry
The thermochemical equation for the combustion of hexane is shown below. C6H14(g) + 19/2Os(g) ==> 6CO2(g) + 7H2O(g) Delta H = -4163kJ What is the enthalpy change for the combustion of 2.50g C6H14? 2.50 g/86g = .029 mol -4163kJ/.029 = -1.43 x 10^5kJ
May 12, 2009 by Steve

Math
Julie is conducting an experiment where she placed 29.5 mL of water in a calorimeter at 15.0 C. Then, 2.4 g of A (molar mass = 48.0 g/mol), also at 15.0C, is added to the water in the calorimeter and the temperature of the solution increases to 28.0 C. The following ...
October 5, 2014 by Kelly

science-chemistry
please anwser soon, a rigid 4.10L flask contains a mixture of 1.25 moles of H2, 0.250 mole of O2, and sufficient Ar so that the partial pressure of Ar in the flask is 1.00 atm. The temperature is 63.5 degrees C A) Calculate the total pressure in the flask B) calculate the mole...
April 29, 2012 by Bryan

Chemistry
Explain why the absolute values of the standard enthalpy change in the reaction and heat measured by the calorimeter are not equal. Assume that there are no measurement errors of any kind. In the previous problem I solved that Delta H rxn was -1500 and q = 1.519 x 10^6 J and I...
March 17, 2012 by David

Chemistry LAB 1
What is the Molar Enthalpy of Neutralization in kJ/mol if 5.00 moles of HCl(aq) (acid) neutralized 5.00 moles of NaOH(aq) (base) and released 6649J of heat? *Make sure you report your answer using the correct sign* DrBob222 gave me some help and I worked it out and got 1329.8 ...
November 6, 2013 by BRANDIE

chemistry - quant.
I need help calculating the pH of a solution that is .0400M Na3AsO4 I was trying to calculate the pH with [H30+]=sqrt(ka1*ka2) What is the correct way to calculate this? Thankyou
December 13, 2007 by anon

physics
A 5.40 Kg package slides 1.47 meters down a long ramp that is inclined at 11.6 degress below the horizontal. The coefficient of kinetic friction between the package and the ramp is = 0.313. Calculate the work done on the package by friction. Calculate the work done on the ...
December 3, 2012 by clariza gonzalez

physics
A bowling ball of mass 7.45 kg is rolling at 2.56 m/s along a level surface. (a) Calculate the ball's translational kinetic energy. J (b) Calculate the ball's rotational kinetic energy. J (c) Calculate the ball's total kinetic energy. J (d) How much work would have to be done ...
March 6, 2015 by alba

Physics
A bowling ball of mass 7.45 kg is rolling at 2.56 m/s along a level surface. (a) Calculate the ball's translational kinetic energy. J (b) Calculate the ball's rotational kinetic energy. J (c) Calculate the ball's total kinetic energy. J (d) How much work would have to be done ...
March 6, 2015 by Yesica

physics
A bowling ball of mass 7.45 kg is rolling at 2.56 m/s along a level surface. (a) Calculate the ball's translational kinetic energy. J (b) Calculate the ball's rotational kinetic energy. J (c) Calculate the ball's total kinetic energy. J (d) How much work would have to be done ...
March 19, 2015 by alba

Physics
A motorboat is traveling 5m/s East, and encounters a current traveling 2.5m/s, North. If the witdth of the river is 80m wide, how much time does it take the boat to reach the other shore. I understand how to calculate the resulatant velocity, but I dont understand why you use ...
October 20, 2010 by Jennifer

Chemistry
H2O(l) = H2O(g) deltaHvap = + 40.7kJ shows the change in enthalpy when 1mol of liquid water vaporizes into water vapor. This is called the molar heat of vaporization. Given this information which is the proper value for the molar heat of condensation?
April 5, 2010 by Tori

Chemistry
The phrase the heat absorbed or released by a system undergoing a physical or chemical change at constant pressure is a. the change in enthalpy of the system. b. the change in internal energy of the system. c. the definition of a state function. d. the temperature change of ...
July 2, 2013 by Jessica

Chem
A gas is compressed from 73.7 L to 1.9 L at 0.70 atmospheres? In addition a total of 4400 J of heat are gained from warmer surroundings. What is the change in internal energy in kJ? I have a general idea of how to do this, but I tried and got -2851.8, which isn't right. What ...
October 19, 2012 by Anonymous

Science
Write the formula, substitute numbers and units(labels)Mike mixed 20g of 60C water with 40g of 25C water. The final temperature was 39C. 1.Calculate the change of temperature for hot water. 2.Calculate the calories transferred from the hot water. 3.Calculate the amount of heat...
March 29, 2010 by Jamie

Chemistry -please help!
A zinc-copper battery is constructed as follows at 25C. Zn|Zn^2+ (0.15 M)||Cu2+(3.00 M)|Cu The mass of each electrode is 200. g. a) Calculate the cell potential when this battery is first connected. - i got this to be 1.14V b.) Calculate the cell potential after 10.0 A of ...
April 28, 2011 by Mandy

Chem
(a) The molar solubility of Ag2CrO4(s) at 35C is 1.3 10-4 mol/L. Calculate Ksp. (b) If 0.0490 g of AgIO3 dissolves per liter of solution, calculate the solubility-product constant. (c) Using the appropriate Ksp value from Appendix D, calculate the solubility of Cu(OH)2 in ...
April 27, 2011 by Rebekah

physics
A resistor (R = 900 ), a capacitor (C = 0.25 F), and an inductor (L = 2.0 H) are connected in series across a 240 Hz AC source for which Vmax = 140 V. Calculate values for the following. ---I only need help with part c---- c) the phase angle between the current and voltage ...
August 5, 2007 by asmi

chem
The combustion of hydrogenoxygen mixtures is used to produce very high temperatures (approximately 2500 C) needed for certain types of welding operations. Consider the reaction to be H2(g) + 1/2O2(g) --> H20(l) Standard enthalpy is -241.8kj What is the quantity of heat ...
October 3, 2008 by tomi

phys
An airplane is heading due south at a speed of 590 km/h. If a wind begins blowing from the southwest at a speed of 65.0 km/h (average). Calculate magnitude of the plane's velocity, relative to the ground. Calculate direction of the plane's velocity, relative to the ground. ...
September 15, 2009 by physics

molarity
calculate the molarity of k+ in a soln prepared by adding .2L of .200M K3PO4 and 75.0mL of .5M K3PO4. assume volumes are additive. A few of steps here and more than one way to answer the problem You need to calculate the total number of moles of K3PO4 from the two volumes and ...
April 5, 2007 by Christine

chemistry
The enthalpy change for the solution process when solid sodium hydroxide dissolves in water is -44.4 kJ/mol. When a 13.6 g sample of NaOH dissolves in 250.0 g of water in a coffee-cup calorimeter, the temperature increases from 23.0 o C to __________ o C. Assume that the ...
November 15, 2010 by Anonymous

Chemistry
Caluclate the delta H for this reaction using standard enthalpies of formation. (The standard enthalpy of formation of liquid pentane is -146.8kJ/mol. Balanced equation balanced equation: C5H12(l)+8O2(g)-->5CO2+6H2O(g) CO2=393.5 H2O=40.7
December 4, 2010 by Ashley

thermodynamics
A scuba tank contains 1.5 kg. of air. The air in the tank is initially at 15 degree celcius. The tank is left near an engine exhaust line, and the tank's pressure doubles. Determine the final temperature, change of internal energy, change of enthalpy, and heat.
November 29, 2011 by hermie

Hudson
In a calorimetric experiment, 6.48 grams of lithium hydroxide was dissolved in water. The temp of the calorimeter rose from 25 celcius to 36.66 celcius. What is the molar change in enthalpy for this procces? LiOH(s) -> Li(aq) + OH (aq) (the heat capacity of the calorimeter ...
October 8, 2012 by k-dawg

chemistry
for a particular isomer C8H18, the following reaction produces 5113.3 kj of heat per mole of C8H18 consumed under standard conditions c8h18(g) + 25/2 O2 (g) ---> 8co2(g) + 9h2o(g) what is the standard enthalpy of formation of this isomer of c8h18? o2= 0 co2(g)= -393.5 h2o(g...
June 19, 2013 by Annie

chemistry
2. If the accepted enthalpy change value for the dissolving of sodium hydroxide in water is −44.2 kilojoules per mole, determine the percent error of the experimental value that you calculated in Part I. Show your work. (experimental - actual value) / actual value 100 %
July 18, 2013 by yuppp

Chemistry
I just did an experiment on the enthalpy of combustion of different alcohols, and for my report, I've written that the condition of the wick is a source of random error, but i can't seem to explain it. I've written that it affects the rate of burning of the flame, and the heat...
April 7, 2009 by TP

Chemistry
Dr.Bob, this is regarding to the enthalpy posts.... I don't understand why you just switch it to negative??How do you know that it is neg???? I thought it started out neg though the problem does not give the number.... I am sorry,but I am a very slow learner...thank you for ...
November 15, 2013 by Anonymous

physics
A stone is projected upward at an angle of 60degree to the horizontal from the top of a tower of height 100meter and it hits the ground at a point. If the initial velocity of projection is 100meter. Calculate the maximum height of the stone above the ground. Calculate the time...
January 3, 2012 by John

physics
A stone is projected upward at an angle of 60degree to the horizontal from the top of a tower of height 100meter and it hits the ground at a point. If the initial velocity of projection is 100meter. Calculate the maximum height of the stone above the ground. Calculate the time...
January 3, 2012 by John

chemistry
How do you calculate the theoretical cell voltage? 1) Zn|Zn^+2 (1M)| Cu|Cu^+2 (1M) 2) Cu|Cu^+2 (1M)| Zn|Zn^+2 (1M) 3) Fe|Fe^+2 (1M)| Cu|Cu^+2 (1M) 4) Zn|Zn^+2 (1M)| Cu|Cu^+2 (0.1M) 5) Cu|Cu^+2 (1M)| Cu|Cu^+2 (0.1 M) Now 4 and 5 have different moles how do you calculate those ...
July 19, 2012 by fenerbahce

Math
An airplane is heading due south at a speed of 590km/h. If a wind begins blowing from the southwest at a speed of 65.0km/h (average). Calculate magnitude of the plane's velocity, relative to the ground. Calculate direction of the plane's velocity, relative to the ground. ...
September 12, 2009 by Anne

Chemistry
Lead has a melting point of 327C, its specific heat is J/gdeg, and its molar enthalpy of fusion is 4.80 kJ/mol. How much heat, in kilojoules, will be required to heat a 500.0-g sample of lead from 23.0C to its melting point and then melt it?
November 4, 2012 by steph

Chemistry
Lead has a melting point of 327C, its specific heat is J/gdeg, and its molar enthalpy of fusion is 4.80 kJ/mol. How much heat, in kilojoules, will be required to heat a 500.0-g sample of lead from 23.0C to its melting point and then melt it?
November 4, 2012 by steph

chemistry
The normal boiling point of ethanol is 78.5C. Using the following information: delta H formation (C2H5OH (g))= -234.38 kJ/mol determine the enthalpy of vaporization of ethanol. I know it should be around 39.3 according to a table in my textbook, however, I don't know how to ...
July 18, 2012 by Kellie

chemistry-lattice energy
Determine the lattice energy for CaBr2 if the enthalpy of solution for CaBr2 is -145 kJ/mol, and the heats of hydration for Ca2+ and Br- are -1650 kJ/mol and -292 kJ/mol respectively.
October 1, 2012 by Bru

Physics
A worker applies a constant force of magnitude F = 339 N on a crate in a direction = 26.1o above the horizontal as he pulls it across a level floor through a distance of s = 7.20 m. The mass of the crate is m = 53 kg and the coefficient of kinetic friction between the floor ...
December 18, 2012 by Sara H

chem
a buffer is made by adding 150 ml of .595M BaF2 and 0f .500M of HF solution. calculate the pH of this buffer system calculate the pH of this buffer after adding .100 mol Hcl calculate the pH of this buffer after adding .0750 mol Ca(OH)2 ka(HF)= 6.9x10^-4 kb(F-)= 1.4 x 10^-11
March 1, 2010 by simi

Chemistry
A total of 2.00 mol of a compound is allowed to react in a foam coffee cup that contains 141 g of water. The reaction caused the temperature of the water to rise from 21.0 to 24.7 degrees Celsius. What is the enthalpy of this reaction? Assume that no heat is lost to the ...
October 11, 2010 by Karen

chemistry
I believe the answer is c I just wanted to make sure. What can help overcome a positive enthalpy of solution and allow a solid solute to dissolve in water? A. A decrease in entropy B. A large amount of energy released C. An increase in entropy D. A large amount of energy absorbed
March 17, 2015 by Cortney

chem please help drbob222
What will be the result of a reaction if its enthalpy change is positive, its entropy change is negative and Gibbs free energy is positive? A. Spontaneous, if the temperature is high B. Nonspontaneous, if the temperature is low C. Always spontaneous D. Never spontaneous
November 26, 2014 by Morgan

physics
A 5.20 package slides 1.57 down a long ramp that is inclined at 13.0 below the horizontal. The coefficient of kinetic friction between the package and the ramp is = 0.305 Calculate the work done on the package by friction. Calculate the work done on the package by gravity. ...
October 4, 2012 by Matt

physics
A 5.20 package slides 1.57 down a long ramp that is inclined at 13.0 below the horizontal. The coefficient of kinetic friction between the package and the ramp is = 0.305 Calculate the work done on the package by friction. Calculate the work done on the package by gravity. ...
October 5, 2012 by Matt

Chemistry
I need help on how to calculate the following please: Calculate the risk assesment of the amount of the ozone in the air between the hours of 4pm and 6pm where I live(Corpus Christi,Texas)
August 27, 2011 by Jelly

chemistry
Which of the following equations represents a reaction for which the delta H can be called a standard enthalpy of formation, delta Hf? a) FeO(s) + CO2(g) -> FeCO3(s) b) 1/2 N2(g) + 2 O(g) -> NO2(g) c) 2 Na(s) + Cl2(g) -> 2 NaCl(s) d) Ba(s) + N2(g) + 3 O2(g) -> Ba(...
January 23, 2012 by timmy

Chemistry
Given the following hypothetical equations, 2A + B → 3C + 2D ΔH = -46.7kJ C → B ΔH = 13.1kJ 2E → B ΔH = 84.5kJ, what is the enthalpy change (kJ) for the following reaction? A → D + 2E
March 7, 2012 by John

Physics
NEED HELP On a flat battle ground, a catapult is used to launch a rock with a velocity of 25m/s at angle 30 degrees above the horizontal.? Sketch the situation and decompose the initial velocity vector. WHat are the initial values for Vx and Vy? Calculate the maximum height ...
August 19, 2014 by Jeesha

Physics
The following figure represents the ride for a cart with a mass of 200 kg along a frictionless track. a. Calculate the velocity of the cart at points A, B, and C if the cart is dropped from a height of 100m with a initial velocity of 10 m/s. b. Calculate the height of the ...
July 25, 2014 by Liz

Chemistry
Why wouldn't you do this reaction directly in a lab (and would rather use Hess' Law to determine the enthalpy of formation)?: 1/2N2(g) + 2H2(g)+ 1/2Cl2(g) -> NH4Cl(s) I don't think the reactants are that dangerous...? It's still pretty safe to do in a lab, isn't it? Are ...
February 18, 2013 by a Canadian

Chemistry
Mass (before reaction): test tube + HCl(aq) + stir bar + capsule 26.600 g Mass (after reaction): test tube + HCl(aq) + stir bar + capsule 25.300 g Volume of water displaced from the squirt bottle 148 mL Temperature of the CO2(g) 287.4 K Pressure (atm) 1.032 atm Using this data...
October 21, 2012 by Karina

chemistry
A. Strong Base 1.) What is the concentration of a solution of KOH for which the pH is 11.89? 2.) What is the pH of a 0.011M solution of Ca(OH)2? B. Weak Acid 1.) The pH of a 0.060M weak monoprotic acid HA is 3.44. Calculate the Ka of the acid. 2.) The pH of 0.100M solution of ...
January 20, 2011 by jaycab

chemistry
the enthalpy of fusion of ice is 6.02 kJ/mol. the heat capacity of liquid water is 75.4 J/molC. What is the smallest number of ice cubes at 0 degrees C each containing one mole of water, necessary to cool 500g of liquid water initially at 20.0 degree C to 0.0 degree C
May 24, 2011 by el

Physics
A stone that starts at rest is in free fall for 8.0 s. a.Calculate the stone's velocity after 8.0 s. b. What is the stone's displacement during this time? Given: t = 8.0 s a = 9.81 m/s^2 For a, in order to calculate the velocity, should i use d = vit + 1/2 at^2 and only use ...
December 25, 2009 by Priscilla

Maths
The distance from TDC (top dead centre) for the pin is given by x when the crank is at angle . Hence : i) Give an equation for x in terms of the other variables (r, L and ). ii) If the crank rod is rotating at a constant value of ω calculate the speed of ...
May 17, 2011 by Karl Haxell

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