Okay! A lot of chemistry questions from me, I'll admit, but it is my worst subject. So, in class we did an experiment about Hess' Law. The main purpose of the investigation was to analyse the results and find the ΔH values of each part of the reaction, thereby confirming Hess' Law. But, I'm not exactly sure how to do that and I can't seem to find a straight answer anywhere for doing that. Perhaps someone on here could help me?
I'll post the main details of the experiment below:
(1)Reaction 1: Solid Sodium Hydroxide dissolves in water to form an aqueous solution of ions:
NaOH(s) * Na+(aq) + OH-(aq)
*H1 = -x1 J
a) Put 50 (±1) ml of cool tap water into the calorimeter. Place the Data Studio probe into the vessel. Stir carefully until a constant temperature is reached (about room temperature). Measure this temperature as precisely as possible, and record it.
b) Weigh out about 2 g of solid Sodium Hydroxide, NaOH(s), as quickly as possible.
c) Pour the weighed NaOH(s) into the water in the calorimeter. Place the probe into the solution and stir gently but continuously until the sodium hydroxide is dissolved. Record the extreme temperature reached. Before proceeding to Reaction 2, discard the solution and rinse the cup thoroughly with water
Temperature reading – 21
Extreme temperature after solid added -27
(2)Reaction 2: Solid Sodium Hydroxide reacts with Hydrochloric Acid to form Water and an aqueous solution of Sodium Chloride:
NaOH(s) + H+(aq) + Cl-(aq) *
H20 + Na+(aq) + Cl-(aq)
*H2 = -x2 J
a) Repeat steps a, b and c of Part 1, but substitute 50 ml of 0.50 M HCl for tap water in step a.
b) Discard the solution and rinse the cup before proceeding to Reaction 3
Temp reading for naoh –21
Extreme temp for naoh after solid added – 35
calorimeter warm, liquid smoky lime green colour
(3)Reaction 3: An aqueous solution of Sodium Hydroxide reacts with Hydrochloric Acid to form Water
Na+(aq) + OH-(aq) + H+(aq) + Cl-(aq) *
H20 + Na+(aq) + Cl-(aq)
*H3 = -x3 J
a)Measure 25 ml of 1.0 M HCl into the calorimeter and 25 ml of 1.0 M NaOH into a 50-ml beaker. Both of these solutions should be at, or slightly below, room temperature. Check this with the probe (rinse and dry the probe before changing from one solution to the other). Record the temperatures.
b) Add the Sodium Hydroxide solution to the Hydrochloric Acid solution in the calorimeter. Mix quickly and record the highest temperature reached.
Temp for HCL-22
Temp for naoh – 21
Extreme temp for both -27
Little bit warm but still clear
TASK:
1.DETERMINATION OF THE ΔH VALUES FOR THE REACTIONS INVOLVING THE DISSOLVING OF SOLID SODIUM HYDROXIDE,
2.THE NEUTRALIZATION OF HYDROCHLORIC ACID BY A SOLUTION OF SODIUM HYDROXIDE
3.AND THE NEUTRALIZATION OF HYDROCHLORIC ACID BY SOLID SODIUM HYDROXIDE.
4.THE CONFIRMATION OF HESS’S LAW.
Help please? :3;; I put in my temperature readings, if that was at all helpful
I'll post the main details of the experiment below:
(1)Reaction 1: Solid Sodium Hydroxide dissolves in water to form an aqueous solution of ions:
NaOH(s) * Na+(aq) + OH-(aq)
*H1 = -x1 J
a) Put 50 (±1) ml of cool tap water into the calorimeter. Place the Data Studio probe into the vessel. Stir carefully until a constant temperature is reached (about room temperature). Measure this temperature as precisely as possible, and record it.
b) Weigh out about 2 g of solid Sodium Hydroxide, NaOH(s), as quickly as possible.
c) Pour the weighed NaOH(s) into the water in the calorimeter. Place the probe into the solution and stir gently but continuously until the sodium hydroxide is dissolved. Record the extreme temperature reached. Before proceeding to Reaction 2, discard the solution and rinse the cup thoroughly with water
Temperature reading – 21
Extreme temperature after solid added -27
(2)Reaction 2: Solid Sodium Hydroxide reacts with Hydrochloric Acid to form Water and an aqueous solution of Sodium Chloride:
NaOH(s) + H+(aq) + Cl-(aq) *
H20 + Na+(aq) + Cl-(aq)
*H2 = -x2 J
a) Repeat steps a, b and c of Part 1, but substitute 50 ml of 0.50 M HCl for tap water in step a.
b) Discard the solution and rinse the cup before proceeding to Reaction 3
Temp reading for naoh –21
Extreme temp for naoh after solid added – 35
calorimeter warm, liquid smoky lime green colour
(3)Reaction 3: An aqueous solution of Sodium Hydroxide reacts with Hydrochloric Acid to form Water
Na+(aq) + OH-(aq) + H+(aq) + Cl-(aq) *
H20 + Na+(aq) + Cl-(aq)
*H3 = -x3 J
a)Measure 25 ml of 1.0 M HCl into the calorimeter and 25 ml of 1.0 M NaOH into a 50-ml beaker. Both of these solutions should be at, or slightly below, room temperature. Check this with the probe (rinse and dry the probe before changing from one solution to the other). Record the temperatures.
b) Add the Sodium Hydroxide solution to the Hydrochloric Acid solution in the calorimeter. Mix quickly and record the highest temperature reached.
Temp for HCL-22
Temp for naoh – 21
Extreme temp for both -27
Little bit warm but still clear
TASK:
1.DETERMINATION OF THE ΔH VALUES FOR THE REACTIONS INVOLVING THE DISSOLVING OF SOLID SODIUM HYDROXIDE,
2.THE NEUTRALIZATION OF HYDROCHLORIC ACID BY A SOLUTION OF SODIUM HYDROXIDE
3.AND THE NEUTRALIZATION OF HYDROCHLORIC ACID BY SOLID SODIUM HYDROXIDE.
4.THE CONFIRMATION OF HESS’S LAW.
Help please? :3;; I put in my temperature readings, if that was at all helpful