Saved Bookmarks
| 1. |
When100mL of 1.0 M HCl was mixed with 100 mL of 1.0 M NaOH in an insulated beaker at constant pressure, a temerature increase of 0.7^(@)C was measured for the beaker and its contents (Expt. 1 ) . Because the enthalpy of neutralization of a strong acid with a strong base is a constant (-57.0 kJ "mol"^(-1)), the experiment could be used to measure the calorimeter constant. Ina second experiment (Expt. 2), 100 mL of 2.0 M acetic acid (K_(a)=2.0xx10^(-5)) was mixed with 100 mL of 1.0 M NaOH . (under identical conditions of Expt.1) where hte temperature rise of 5.6^(@)C was measured. (Consider heat capacity of all solutions as 4.2 Jg^(-1) K^(-1) and density of all solutions as 1.0 m mL^(-1)) The pH of the solution after Expt. 2 is |
|
Answer» 2.8 NAOH present in 100 mL of 1.0 M solution = 0.1 mole 0.1 mole of NaOH NEUTRALIZES 0.1 mole of NaOH to form 0.1 mole of `CH_(3)CO ON a` `:. ` In the final solution, `CH_(3)CO OH` = 0.1 mole, `CH_(3)CO ONa`= 0.1 mole, i.e., it is a buffer solution `pH = pK_(a) + log. (["Salt"])/(["Acid"])=-log(2XX10^(-5))+log.(0.1)/(0.1)` `=-log(2xx10^(-5))` `=5-0.301=4.699~= 4.7` |
|