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September 22, 2014

Search: calculate the enthalpy change

Number of results: 27,688

chemistry
The reaction between 0.045 g of calcium with an excess of water was carried out in an ice calorimeter as used in this lab. The volume of water in the calorimeter decreased by 0.18 mL during the reaction a) Write the equation for the reaction which occurs. Is it a redox ...
November 10, 2008 by Anonymous

Chemistry
A coffee-cup calorimeter initially contains 125 g water at 24.2 degrees celsius. Potassium bromide (10.5 g), also at 24.2 degree celsius, is added to the water, and after the KBr dissolves, the final temperature is 21.1 degrees celsius. Calculate the enthalpy change for ...
February 13, 2012 by Elle

Thermodynamics
I am doing a lab and there is one question I can't get. We have the enthalpy of fusion of crystalline polyeythlene, mass, onset temperature and energy required for a phase change of both low density polyethylene and high density polyethylene. They as to calculate the percent ...
September 23, 2007 by Tracy

Thermodynamics
I am doing a lab and there is one question I can't get. We have the enthalpy of fusion of crystalline polyeythlene, mass, onset temperature and energy required for a phase change of both low density polyethylene and high density polyethylene. They as to calculate the percent ...
September 24, 2007 by Tracy

CHEMISTRY
Post a New Question Current Questions Homework Help: Chemistry Posted by Anonymous on Thursday, November 14, 2013 at 8:45pm. CONTINUE>>>>>>>>>>> The enthalpy changes for two different hydrogenation reactions of C2H2 are: C2H2+H2---->C2H4 ...
November 14, 2013 by Anonymous

Chemistry
Okay so I'm doing an assignemtn and one of the questions has stumped me. It asks: The solid fuel booster rockets on the space shuttle employ a mixture of aluminium and ammonium perchlorate. The reaction is: 2Al(s) + 2NH4ClO4(s) → Al2O3(s) + 2NO(g) + 3H2O(g) + 2HCl(g) Use the...
January 21, 2007 by Tracy

chemistry
say A -> B + 5kJ would reactants have more enthalpy or products have more enthalpy? I think first, the delta H would be negative. So H final must be less than H initial. So reactants have more enthalpy?
February 27, 2008 by william

chemistry
When 15.3g of NaNO3 was dissolved in water inside a constant pressure calorimeter, the temperature fell from 25.00 C to 21.56 C. If the heat capacity of the calorimeter (including the water it contains) is 1071 J/C, What is the enthalpy change for dissolving 1 mole of NaNO3...
March 4, 2011 by Stephen

Chemistry
with a platinum catalyst, ammonia will burn in oxygen to gove nitric oxide NO. What is the enthalpy change for the following reaction? NO + 3/2 H2O -----> NH3 + 5/4 O2
October 29, 2007 by Lauren

chemistry
Can someone help me with this question? what two conditions must be met by a thermochemical equation so that its standard enthalpy change can be given the symbol delta Hf?
October 12, 2010 by Leslie

Chemistry
If 1 mol of ice melts at its melting point of 273 K, the entropy change for the ice is 22.0 J/K. If the ice melts in someones hand at 34C, what is the change in the entropy of the universe? Assume a final temperature for the water of 0C. The enthalpy of fusion for ice is 6....
July 30, 2012 by Taylor

CHEMISTRY
If 1 mol of ice melts at its melting point of 273 K, the entropy change for the ice is 22.0 J/K. If the ice melts in someones hand at 34C, what is the change in the entropy of the universe? Assume a final temperature for the water of 0C. The enthalpy of fusion for ice is 6....
August 1, 2012 by MONICA

chemistry
The fermentation of sugar (C6H12O6) to form ethanol (C2H5OH) and carbon dioxide (CO2) occurs according to the following equation: C6H12O6(aq) 2 C2H5OH(aq) + 2 CO2(g) kJ molC1 Hf (C6H12O6(s)) is C1275 Hf (C2H5OH(l)) is C277 Hbond (C=O) 799 (a) Assuming the heat of ...
November 3, 2010 by mailyn

Chemistry practice
Calculate using the enthaly of formation,the enthalpy of combustion of methanol,CH3OH
July 31, 2011 by Gift

Chemistry
Calculate the enthalpy of combustion for acetic acid using standard enthalpies of formation.
November 12, 2012 by Diana

Chemistry
From your experience, predict which of the following reactions are spontaneous. a) Zn(s) + 2H+(aq)--> Zn+2(aq) + H2 (g) b) CaCO3(s) + 2H2O(l) --> Ca(OH)2(s) + H2CO3(aq) c) CH4(g) + O2(g) --> CO2(g) + 2H2O(g) d) Ag+(aq) + Cl-(aq) --> AgCl (s) Our book spends very ...
February 14, 2007 by Chris

chem
I got through the first part easily, got -352.9kJ Having trouble with the second part "The meals-ready-to-eat (MREs) in the military can be heated on a flameless heater. The source of energy in the heater is shown below. Mg(s) + 2 H2O(l) Mg(OH)2(s) + H2(g) Calculate the ...
November 20, 2010 by Anonymous

Chemistry
A calorimeter contains 21.0 mL of water at 14.0 degreesC. When 1.90 g of X (a substance with a molar mass of 70.0 g/mol) is added, it dissolves via the reaction X(s)+H_2O(l)reacts to make X(aq) and the temperature of the solution increases to 28.5degreesC. Calculate the ...
October 22, 2010 by Ellen

chemistry
2 Mg(s) + O2(g)= 2 MgO(s) H= -1204 kJ How many grams of MgO are produced during an enthalpy change of 96.0 kJ?
October 2, 2009 by Vanessa

chemistry
what is the molar enthalpy change when 147 g of water cools from 90.0 degrees C to 17.0 degrees C
October 10, 2012 by sam smith

chemistry
Using the equations and enthalpy values provided, which mathematical expression can be used to determine the unknown enthalpy change of the decomposition of propane? 3 C + 3 O2 3 CO2 H =-1182 kJ 4 H2 + 2 O2 4 H2O H = -1144 kJ C3H8 + 5 O2 3 CO2 + 4 H2O H = -2222 kJ C3H8 3 C + 4...
June 17, 2011 by bryan

chemistry
What is the change in enthalpy for an isothermal, isentropic compression of an ideal gas from 2 atm to 12 atm?
October 23, 2013 by Carl

engineering
What is the change in enthalpy for an isothermal, isentropic compression of an ideal gas from 2 atm to 12 atm?
October 23, 2013 by Carl

chemistry, please help
2NO2(g)--> 2NO(g) + O2(g) , H=+114.2kJ (Note: H, S, G all have a degree sign next to them) NO: H(enthalpy)=90.3kJ/mol, S(entropy)=210.7J/mol*K, G(gibbs energy)=86.6 O2: H(enthalpy)=0, S(entropy)=?, G(gibbs energy)=0 kJ/mol NO2: H(enthalpy)=33.2, S=239.9, G=51 For part a, I ...
February 4, 2008 by apoorva

chemistry
The concept of free energy allows prediction of spontaneity of a process by considering the changes in ________ and ________ during the process. A) entropy; temperature B) enthalpy; mass C) enthalpy; entropy D) enthalpy; temperature E) entropy; mass
November 9, 2009 by brandy

Chemistry
This isn't exactly a homework question, I'm just trying to understand the concept we learned today... So say we had: 4Fe + 3O2 → 2Fe2O3 + 1.65 x 10^3 kJ Does that mean for every 4 mol of Fe, 3 mol of O2, and 2 mol of Fe2O3 we have 1.65 x 10^3 kJ? And if I were to ...
February 6, 2013 by A Canadian

CHEMISTRY LAB
If the molecular mass for a chemical is 45.99 g/mol and the enthalpy of formation is 34 kJ/mol, the heat change will be
February 21, 2010 by Mary

CHEM LAB
Calculate the Molar Enthalpy of Neutralization in kJ/mol of the reaction between a monoprotic acid and a monoprotic base, given the following information: *Make sure you report your answer using the correct sign* The temperature change equals 9.80 degrees C, 50.0mL of 1.00 M ...
November 6, 2013 by BRANDIE

CHEM LAB
Calculate the Molar Enthalpy of Neutralization in kJ/mol of the reaction between a monoprotic acid and a monoprotic base, given the following information: *Make sure you report your answer using the correct sign* The temperature change equals 9.80 degrees C, 50.0mL of 1.00 M ...
November 6, 2013 by BRANDIE

chem
Cydohexanol has a vapor pressure of 10mHg at 56C and 100mmHg at 103.7C. Calculate its enthalpy of vaporization.
January 18, 2011 by lennie

chemistry
calculate the enthalpy of mixing for the solution of 10% platinum and 90% gold .express your answer in units of kg/mole
May 7, 2013 by himani.

Chemistry
Why is the enthalpy of the reactants greater than the enthalpy of the products in an exothermic reaction? If it has something to do with the reactants having weaker bonds, why do weaker bonds have higher energy/enthalpy? It doesn't really make sense to me that weaker bonds ...
February 18, 2013 by a Canadian

ThermoChemistry
If 18 g of Kr initially at 0.5 bar and 18 L is brought to 0.49 bar and 5L, what is the overall change in enthalpy of this process? Assume that Kr is an ideal gas.
December 2, 2011 by LaurenB

chemistry
The enthalpy change for the reaction below at 25oC is -2,051 kJ (per mole of C10H22). What is the internal energy change for the reaction at 25oC? 10 CO(g) + 21 H2(g) --> C10H22(l) + 10 H2O(l) Enter your answer in kJ (per mole of C10H22), rounded to the nearest kilojoule.
March 1, 2014 by abby

Chemistry
The enthalpy of solution of CaCl2 is -82.88kJ. If the specific heat of the solution is 4.184J/g*C and the calorimeter constant can be neglected, what will be the final temperature after 5.36g of CaCl2 is dissolved in 100.0g of H2O at 25.0C? I assume the enthalpy given is kj/...
May 20, 2007 by Em

chemistry
The heat of vaporization of liquid water at 373 K is 40.7 kJ/mol. The value of the enthalpy change when 2.00 g of steam condenses at 373 K is?
November 28, 2010 by Anonymous

Chemistry
4 NH3(g) + 5 O2(g) 4 NO(g) + 6 H2O(g) If standard enthalpy change is -906.2 kJ, what quantity of heat is evolved or absorbed in the formation of 17.0 g of NH3?
May 1, 2011 by Kat

Chemistry
Data: C(graphite) + O2(g) forms CO2 (ga) Delta H = -393.5kJ H2(g) + 1/2O2(g) forms H2O(l)Delta H = 285.8kJ. CH3OH(l) + 3/2O2(g)forms CO2(g) + 2H2O(l)Delta H = -726.4 Using data above, calculate the enthalpy change for the raction below C(graphite) + 2H2 +1/2 O2(g) forms CH3OH(l)
October 27, 2010 by lavonne

Chemistry
Calculate the enthalpy change, ΔrH, for the following reaction, 4 NH3 (g) + 5 O2(g) → 4 NO (g) + 6 H2O (g) given the thermochemical equations below. N2 (g) + O2 (g) → 2 NO (g) ΔrH = +181 kJ N2 (g) + 3 H2 (g) → 2 NH3 (g) ΔrH = 91.8 kJ...
October 2, 2011 by Hannah

science
the standard enthalpy of formation of ammonia is -46 kj/mol. if the enthalpy of formation of hydrogen molecule is -436 kj/mol and that of nitrogen molecule is -712 kj/mol find the average bond enthalpy of N-H bond in ammonia
April 1, 2014 by bonnhi

Chemistry
Given the thermochemical equation 2SO2 + O2 → 2SO3, ΔHrxn = -198 kJ/mol, what is the standard enthalpy change for the decomposition of one mole of SO3?
May 5, 2014 by Chris

Chemistry
The molar enthalpy of vaporization for water is 40.79 kJ/mol. Express this enthalpy of vaporization in joules per gram.
November 20, 2012 by Rebecca

chemistry
Ok, I really need to know how to work problems like these so could someone please show me how to set it up?! Given this data: 1. C(graphite) + O2(g) produces CO2(g), delta H = -393.5 kJ 2. H2(g) + 1/2 O2(g) produces H2O(l), delta H = -285.8 kJ 3. Ch3OH(l) + 3/2 O2(g) produces ...
November 23, 2010 by lavonne

Biochemistry
You wish to measure the change in G'for the hydrolysis of ATP: ATP ---> ADP + Pi but the equilibrium for the hydrolysis lies so far toward products that analysis of the ATP concentration at equilibrium is neither practical nor accurate. However, you have the following data...
September 12, 2009 by Mallory

Chemistry LAB 2
Calculate the Molar Enthalpy of Neutralization in kJ/mol of the reaction between a monoprotic acid and a monoprotic base, given the following information: *Make sure you report your answer using the correct sign* The temperature change equals 9.80 degrees C, 50.0mL of 1.00 M ...
November 6, 2013 by BRANDIE

chemistry
CH3OH(g) ----> CO(g) + 2H2 (g) (delta H =+90.7k) A) is heat absorbed or released in the course of this reaction? b) calculate the amount of heat transferred when 45.0g of CH3OH(g)is decomposed by this reaction at constant pressure. c) for a given sample of CH3OH, the ...
October 17, 2011 by Anna

Lauren
Which of the following has a standard enthalpy of formation value of zero at 25 degrees C and 1.0 atm A. Fe(s) B. Fe2O3(s) C. FeSO4(s) D. FeSO4(aq) E. FeS3(s) and what is enthalpy or how do you find it
November 16, 2007 by Chemistry

Chemistry
The enthalpy of combustion of benzoic acid is 26.4 kJ/g. What is the enthalpy of combustion expressed in joules per kilogram?
January 18, 2012 by Cynthia

chemistry
Enthalpy and Entropy in Reactions and Solutions Introduction In the course of most physical processes and chemical reactions there is a change in energy. In chemistry what is normally measured is H (enthalpy change), the change in heat at constant pressure and ignoring any ...
November 30, 2010 by allison

Chemistry
If delta Hrxn and delta Srxn are both positive values, what drives the spontaneous reaction and in what direction at standard conditions? The spontaneous reaction is a)enthalpy driven to the left. b)entropy driven to the right. c)entropy driven to the left. d)enthalpy driven...
April 20, 2014 by Alexis

Chemistry
Part A Calculate the standard enthalpy change for the reaction 2A+B --->2C +2D Use the following data: Substance Delta H(kJ/mol) A -263 B -391 C +203 D -523 Express your answer in kilojoules. MY ANSWER FOR PART A: Delta H =277 kJ PART B----THIS ONE I NEED HELP ON Express ...
June 16, 2011 by tina

Chemistry
Part A Calculate the standard enthalpy change for the reaction 2A+B --->2C +2D Use the following data: Substance Delta H(kJ/mol) A -263 B -391 C +203 D -523 Express your answer in kilojoules. MY ANSWER FOR PART A: Delta H =277 kJ PART B----THIS ONE I NEED HELP ON Express ...
June 16, 2011 by tina

Chemistry
2CH3OH(l)+3O2(g)-->2CO2(g)+4H20 +1350 kj 1. What mass of water could be heated from 20.0 C to 35 C,by burning 48g of methanol? This is what I did, no answer was given so I want to double check. so q=mcT change in H=n(molar enthalpy) c= 4.184 kj/(kg C) So what I did was ...
July 27, 2009 by micheal

Chemistry Urgent
A calorimeter contains 32.0mL of water at 13.0∘C . When 2.30g of X (a substance with a molar mass of 82.0g/mol is added, it dissolves via the reaction X(s)+H2O(l)X(aq) and the temperature of the solution increases to 30.0∘C . Calculate the enthalpy change, H ...
March 11, 2014 by Anna

chemistry
The melting of 0.140 g of Br2 (which occurs at -7.2 C at 1 atm pressure) absorbs 9.43 J of heat. Compute the enthalpy change in 2.00 mol of Br2 when it freezes.
September 1, 2011 by rafay

Chemistry
What is the change in enthalpy when 4.00 mol of sulfer trixoide decomposes to sulfer dioxide and oxygen gas? 2SO2 + O2 ---> 2SO3 delta H = 198kJ
June 24, 2013 by Jessica

chemistry
calculate the enthalpy of formation, per mole, of sucrose, C12H2211O(s). C12H22O11(s) + 12O2(g) --> 12CO2(g) +11H2O(l) deltaH=-5.65*10^3 kJ
March 23, 2011 by Stacy

chemistry
calculate the enthalpy of formation, per mole, of sucrose, C12H2211O(s). C12H22O11(s) + 12O2(g) --> 12CO2(g) +11H2O(l) deltaH=-5.65*10^3 kJ
March 23, 2011 by Stacy

Chemistry (DrBob222)
Hi, here's my (almost) 2-paged lab report introduction (hopefully you remember it from yesterday). I went to class today, and actually a lot of my other classmates' introductions were over 2 pages! Now I'm feeling kind of insecure about mine, and I'm not even sure if 2 pages ...
February 19, 2013 by a Canadian

physical chemistry
1.) Calculate delta rH for the freezing of water at one bar and -10 degrees C. The heat capacities are H2O(s)=36.9 JK-1mol-1 and H2O(l)=74.5JK-1mol-1. delta H for freezing of water at 0 degree C is -6602Jmol-1 (assume C is independent of temperature). 2.) Assume the hot brick ...
February 21, 2012 by nicole

chem
A calorimeter contains 16.0ml of water at 15.0degrees celsius. When 1.60g of X(a substance with a molar mass of 46.0g/mol) is added, it dissolves via the reaction X(s)+H20(l)->X(aq) and the temperature of the solution increases to 25.0degrees celsius. Calculate the enthalpy...
October 8, 2008 by tomi

chemistry
gaseous hydrogen and fluorine combine in the reaction above to form hydrogen fluoride with an enthalpy change of -540kJ. What is the value of the heat of formation of HF(g)
February 17, 2013 by Sarah

Chemistry
What is the enthalpy change if 25.0 g of methane are burned? 890kJ of heat released for every mole of methane that reacts. CH4 + 2O2 = CO2 + 2H2O
March 18, 2014 by Tracy

Chemistry - enthalpy of combustion(help!!!)
i need help with the below question, i have tried answering it, but do not know where to go after the equations, please start me off on how to find the enthalpy of combustion of at least one.... Consider methane, CH4, and hydrogen, H2, as possible fuel sources. (a) Write the ...
June 8, 2011 by Farah

AP Chem
I had to do an experiment to calculate the enthalpy of solution of Epsom salts. I'm stuck on how to calculate the amount of the reactant in moles. Here's some preliminary data: 37.58 g of Epsom salts in the solution Molar mass of solution: 246.48 g/mol I'm not sure what to do ...
December 20, 2012 by Arianna

Chemistry
Calculate the quantity of heat released when 0.520 mol of sulfur is burned in air. uising the enthalpy detalH= -296
March 23, 2010 by Vee

Chemistry
The standard enthalphies of formation of ozone, O3(g), and oxygen atoms are +142.70 and +249.17 kJ/mol. Calculate the reaction enthalpy for 2O2(g)-->O3(g)+O(g)
October 20, 2012 by Sam

Chemistry
Someone said, "Calculate the total delta H of the reaction and subtract the total delta H of the product from it. If you get a positive value, it radiates heat which means it's exothermic. If it is negative, heat is needed to get a reaction so it is endothermic." ...shouldn't ...
February 11, 2013 by A Canadian

Chemistry
Someone said, "Calculate the total delta H of the reaction and subtract the total delta H of the product from it. If you get a positive value, it radiates heat which means it's exothermic. If it is negative, heat is needed to get a reaction so it is endothermic." ...shouldn't...
February 11, 2013 by A Canadian

Chemistry
Ethylene glycol, HOCH2CH2OH, is used as antifreeze. It is produced from ethylene oxide, C2H4O, by the following reaction. C2H4O(g) + H2O(l) → HOCH2CH2OH(l) Use Hess's law to obtain the enthalpy change for this reaction from the following enthalpy changes. 2 C2H4O(g) + 5 ...
December 13, 2009 by Mariam

chemistry
Ethylene glycol, HOCH2CH2OH, is used as antifreeze. It is produced from ethylene oxide, C2H4O, by the following reaction. C2H4O(g) + H2O(l) → HOCH2CH2OH(l) Use Hess's law to obtain the enthalpy change for this reaction from the following enthalpy changes. 2 C2H4O(g) + 5 ...
October 29, 2010 by caroline

Chemistry
The following reaction has a standard enthalpy of reaction of -146.0 kJ/mol: Cu2O(s) + 1/2 O2(g) -> 2CuO(s) The standard enthalpy of formation of Cu2O(s) is -168.6 kJ/mol. What is the standard enthalpy of formation of CuO(s)?
March 11, 2011 by James

Chemistry
CaO(s) + 3C(s) > CaC2(s) + CO(g) deltaHrxn = +464.8 kJ/mol-rxn Is the reaction endothermic or exothermic? What is the enthalpy change if 10.0 g of CaO is allowed to react with an excess of carbon?
December 8, 2010 by Jake

Chemistry
Define a system and state the significant the enthalpy change for the system. Explain your reasoning? A) natural gas burning in a furnace B) melted wax solidifying
September 11, 2013 by Saarah

Chemistry
Calculate the change in PH when 6 ml of 0.1 M HCl is added to 100 ml of a buffer solution that is 0.1 M in NH3 and 0.1 M in NH4Cl. And calculate the change in PH when 6 ml of 0.1 M NaOH is added to the original buffer solution.
March 27, 2012 by Mima

Chemistry
Calculate the change in PH when 6 ml of 0.1 M HCl is added to 100 ml of a buffer solution that is 0.1 M in NH3 and 0.1 M in NH4Cl. And calculate the change in PH when 6 ml of 0.1 M NaOH is added to the original buffer solution.
March 27, 2012 by Mima

chemistry
Insert a complete data table, including appropriate significant figures and units, in the space below. Also include any observations you made over the course of Part I. Aluminum Measured Mass of Metal 41.66 g Distilled Water Measurement 25 mL Distilled Water Temperature 25 C ...
July 7, 2014 by kim

Chemistry
The pH of 0.40 M HF(aq) is 1.93. Calculate the change in pH when 0.301 g of sodium fluoride is added to 53.7 mL of the solution. Ignore any change in volume.
June 14, 2013 by Sara

Chemistry
Is there a value for the enthalpy of vaporization of water at any temperature? Or does the value change with different temperatures? And if there is just one value, do you know what it is?
January 4, 2009 by Unsure

Chemistry
Is there a value for the enthalpy of vaporization of water at any temperature? Or does the value change with different temperatures? And if there is just one value, do you know what it is?
January 4, 2009 by Unsure

Chemistry
Is there a value for the enthalpy of vaporization of water at any temperature? Or does the value change with different temperatures? And if there is just one value, do you know what it is?
January 4, 2009 by Unsure

Chemistry
When 100 mL of Ba(NO3)2 solution at 25 degrees Celsius is mixed with 100 mL solution CaSO4 solution at 25 degrees Celsius in calorimeter, the white solid BaSO4 forms and the temperature of the mixture increases to 28.1 degrees Celsius. Assuming that the calorimeter absorbs ...
December 9, 2012 by Megan

Chemistry
consider the following reaction: 2CH3OH(g) yields 2CH4(g) + O2(g) change in enthalpy= 252.8kJ How many kilojoules of heat are released when 38.4 g of CH_4 g) reacts completely with O2 (g) to form CH3OH (g) at constant pressure?
March 5, 2012 by Dylan

chemistry
enthalpy change^H is +23kJ mol-1 of phosphine (PH3) for the reaction 2P(s)red+3H2(g)---->2PH3(g) a) Calc. entropy change for this reaction. Explain how this information allows you to determine the spontaneity or non-spontaneity of this reaction at any temp (S for PH3 is ...
February 12, 2013 by harry

Chemistry
The combustion of 132 g of propane, C3H8, with excess oxygen liberates 6.6x10^3 kj of heat. What is the enthalpy change for the reaction below: C3H8(g) + 5O2(g) -> 3CO2(g) + 4H2O(l)
October 14, 2012 by Kay

Physics
If I have a diagram of Kepler's laws of planetary motion and it shows change in t1 larger than change in t2 and A1 larger than A2 and asks the question: which of the following is correct? 1.A3 = A3 2.change in t3 > change t3 3.if change t3 = change in t2, then the orbit is ...
November 30, 2010 by JamieLynne

chemistry
Are bond energies (single and multiple bonds) applicable only to gas phase?? For instance, I can use the bond energy data to calculate for enthalpy of reaction for the formation of water: 2 H2(g) + O2(g) -> H2O(g) But I can't directly use it to calculate for neutralization ...
September 19, 2012 by Namie

chem
Are bond energies (single and multiple bonds) applicable only to gas phase?? For instance, I can use the bond energy data to calculate for enthalpy of reaction for the formation of water: 2 H2(g) + O2(g) -> H2O(g) But I can't directly use it to calculate for neutralization ...
September 19, 2012 by Namie

Chemistry
1. The delta Hf of an element in its standard state is defined to be a) 0 kJ/mol b) 10 kJ/mol c) -10 kJ/mol d) greater than 0 kJ/mol e) a unique value for each element I am assuming its a? 2. Which of the following statements are true? I) The reaction vessel cools when an ...
July 21, 2010 by Bobby

Chemistry
With a platinum catalyst, ammonia will burn in oxygen to give nitric oxide, NO. 4NH3 + 5O2 -----> 4NO + 6H2O Delta H= -906 kJ What is the enthalpy change for the following reaction? NO + 3/2H2O ---> NH3 + 5/4O2
October 30, 2007 by Lauren

chemistry
The standard enthalpy of formation for sulfur dioxide gas is -296.8 J. Calculate the amount of energy given off in kJ when 30.0 g of SO2 is fromed from its elements
March 31, 2011 by adam

chemistry
The molar enthalpy of vaporization for water is 40.79 kJ/mol. Express this enthalpy of vaporization in joules per gram. b. The molar enthalpy of fusion for water is 6.009 kJ/mol. Express this enthalpy of fusion in joules per gram.
November 26, 2012 by maryam

Chemistry
Calculate the free energy (ΔG˚) of reaction (kJ) for the equation as written at 298 K (Dependence of temperature on enthalpy can be disregard). If the answer is negative, enter the sign and then the magnitude. Express your answer to three significant figures. CaO(s...
March 13, 2010 by Anonymous

Physics
During an all-night cram session, a student heats up a 0.451 liter (0.451 x 10- 3 m3) glass (Pyrex) beaker of cold coffee. Initially, the temperature is 19.5 C, and the beaker is filled to the brim. A short time later when the student returns, the temperature has risen to 96....
November 17, 2006 by Jena

chemistry
Calculation of )Hf0 for Mg2+(aq.) 1. Assume the heat capacity of the final solution is 3.92 J K-1 g-1. Using the mass of the HCl solution, calculate qcontents from equation (4.6). Calculate qsystem from equation (4.5). 2. Calculate the moles of Mg2+ produced, nrxn. Be sure to ...
March 25, 2011 by Narash

ap chemisrty
Kp for the following reaction is 0.16 at 25C. 2 NOBr(g) 2 NO(g) + Br2(g) The enthalpy change for the reaction at standard conditions is +16.3 kJ. Predict the effect of the following changes on the position of the equilibrium; that is, state which way the equilibrium will ...
February 15, 2011 by sandra

chemistry/thermochem
The bond enthalpy of F2(g) is 156.9 kJ/mol. Calculate Hf for F(g). 1 kJ/mol
October 6, 2010 by myles

Physics-Please check
If I have a diagram of Kepler's laws of planetary motion and it shows change in t1 larger than change in t2 and A1 larger than A2 and asks the question: which of the following is correct? 1.A3 = A3 2.change in t3 > change t3 3.if change t3 = change in t2, then the orbit is ...
November 30, 2010 by JamieLynne

chemistry
2.9 The standard enthalpy of formation of the metallocene bis(benzene)chromium was measured in a calorimeter. It was found for the reaction Cr(C6H6)2(s) → Cr(s) + 2 C6H6(g) that . Find the corresponding reaction enthalpy and estimate the standard enthalpy of formation of...
June 18, 2011 by girlgirl

Changes in Matter
Which of the following are examples of a physical change? a)change in physical state b)change in size or shape c)change in properties d)change in texture e)change in physical quantities f)change in substances Answer: a, b, and d Please correct me if I'm wrong, thanks
March 22, 2010 by Sara

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