Question

In: Chemistry

A. What was the ?H value obtained for NH3 + HCl

A. What was the ?H value obtained for NH3 + HCl

Solutions

Expert Solution

Just applying Hess's Law you get:

[eqn 1] ? NaOH + HCl ? NaCl + H2O ... ?H = -60 kJ/mol

[eqn 2] ? NH3 + HCl ? NH4Cl ... ?H = -38 kJ/mol


required reaction is NaOH + NH4Cl ? NaCl + NH3 + H2O ... ?H =?


[eqn 1] is OK the way it is

BUT [eqn 2] has to be flipped to get stuff on the right sides:

so [eqn 1] ? NaOH + HCl ? NaCl + H2O ... ?H = -60 kJ/mol

[flipped eqn 2] ? NH4Cl ? NH3 + HCl ... ?H = 38 kJ/mol ... [don/t forget to change the sign for ?H]


now [eqn 1] + [flipped eqn 2] ? NaOH + NH4Cl ? NaCl + NH3 + H2O ... ?H = -60 + 38 = -22 kJ/mol ... [the HCls cancel each other]


so from the given data the expected enthalpy change for the required reaction is -22 kJ/mol

not sure what's with the given -11kJ/mol ... Is that the answer they have given?

From what I could find the correct ?H for the reaction should be about -3.9 kJ/mol ... so both answers seem to be way off ... but that's likely b/c a lot of heat could be lost to the surroundings during the lab messing up the results


Related Solutions

WHICH OF THE FOLLOWING REACTIONS REPRESENTS A STRONG ACID? A. HCl ---> H+ +Cl- B. NH3...
WHICH OF THE FOLLOWING REACTIONS REPRESENTS A STRONG ACID? A. HCl ---> H+ +Cl- B. NH3 + H+ <-----> NH4+ C. H2CO3 <----> HCO3- + H+ D. NaOH ---> Na+ +OH- A solution has a pH of 1.0 x 10^(-2)M. What best describes the solution? BASIC ACIDIC SALTY NEUTRAL
a) What is the value of ∆H of the following chemical reaction? NaOH(aq)        +       HCl(aq) ----->...
a) What is the value of ∆H of the following chemical reaction? NaOH(aq)        +       HCl(aq) -----> NaCl(aq)    +             H2O(l)      +                55.216 kJ b) Use the above equation to calculate the amount (in moles) of the water produced if you know that the mass of the solution was 100 g, the temperature change was 3oC, and the specific heat of the solution is 4.184 J/oC.g. c) 54.6 kJ of heat is released when 1 mole of HCl reacts with 1...
In a titration of a 100.0mL 1.00M NH3 solution with 1.00M HCl, what is the pH...
In a titration of a 100.0mL 1.00M NH3 solution with 1.00M HCl, what is the pH of the solution after the addition of 127 mL of HCl? Kb = 1.8 x 10-5 for NH3
1)For the reaction NH4Cl(aq)--->NH3(g) + HCl(aq) H° = 86.4 kJ and S° = 79.1 J/K The...
1)For the reaction NH4Cl(aq)--->NH3(g) + HCl(aq) H° = 86.4 kJ and S° = 79.1 J/K The equilibrium constant for this reaction at 325.0 K is . Assume that H° and S° are independent of temperature. 2)For the reaction Fe(s) + 2HCl(aq)--->FeCl2(s) + H2(g) H° = -7.4 kJ and S° = 107.9 J/K The equilibrium constant for this reaction at 279.0 K is ____ Assume that H° and S° are independent of temperature.
1).If the pH of 1.000 L of HCL is 2.3377, what is the H+? What would...
1).If the pH of 1.000 L of HCL is 2.3377, what is the H+? What would the final pH be if 0.17644 g of NaOH were added? Show the reaction between these 2 compounds 2) The pH of solution .1000 M 2,6-Dinitrophenol (acid form, like [HA] is 1.293. If you determine that the phenolate (anion from the weak acid, like [A-]) is 2.41 x 10^-4 M what is the pKa of 2,6-DNP?
Rank the following in order of increasing acidity: H2O,   NH3,   CH4,   H2S,    HCl CH4,   NH3,   H2O,  ...
Rank the following in order of increasing acidity: H2O,   NH3,   CH4,   H2S,    HCl CH4,   NH3,   H2O,   H2S,   HCl H2O,   NH3,   CH4,   H2S,    HCl NH3,   CH4,   H2S,    H2O,   HCl NH3,   H2O,   CH4,   H2S,    HCl
What is the pH of 10ml of 0.1M NH3, with 5ml of 0.1M of HCL. kb=1.8*10^-5
What is the pH of 10ml of 0.1M NH3, with 5ml of 0.1M of HCL. kb=1.8*10^-5
titration of 50.0mL 0.50M NH3 with 0.50 M HCL. Kb(NH3)=1.8x10^-5 Plot the pH of the solution...
titration of 50.0mL 0.50M NH3 with 0.50 M HCL. Kb(NH3)=1.8x10^-5 Plot the pH of the solution after the addition of the following volumes of HCL using ICE tables. 0.00mL, 10.00mL, 20.0mL, 25.0mL, 30.0mL, 40.0mL, 50.0mL,, 60.0mL
What nitrogen and hydrogen orbitals overlap to form each N–H ? bond in NH3.
What nitrogen and hydrogen orbitals overlap to form each N–H ? bond in NH3.
The following chemical species are mixed: [ H+] = 0.25 M [NH3] = 0.25 M What...
The following chemical species are mixed: [ H+] = 0.25 M [NH3] = 0.25 M What kind is formed in the balance? And what is the pH of the solution?
ADVERTISEMENT
ADVERTISEMENT
ADVERTISEMENT