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Heats of Reaction Lab Report

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Heats of Reaction Lab Report

Purpose: To measure the heats of reaction for three related exothermic reactions and to verify Hess’s Law of Heat Summation.

NaOH(s) ( Na+(aq) + OH-(aq) ΔH = -10.6kcal/mol
NaOH(s) + H+(aq) + Cl-(aq) ( H2O + Na+(aq) + Cl-(aq) ΔH = -23.9kcal/mol
Na+(aq) + OH-(aq) + H+(aq) + Cl-(aq) ( H2O + Na+(aq) + Cl-(aq) ΔH = -13.3kcal/mol

Background: Energy changes occur in all chemical reactions; energy is either absorbed or released. If energy is released in the form of heat, the reaction is called exothermic.
If energy is absorbed, the reaction is called endothermic.

Materials: spatula sodium hydroxide pellets (NaOH) 1 Styrofoam cup 1.0 M sodium hydroxide (NaOH) 1 100-mL graduated …show more content…

Determine the change in temperature for each reaction. Show work here and record your answer in Data Table 2. 2. Calculate the mass of the reaction mixture in each reaction first by determining the volume of the solution and then assuming that the density of the solution is the same as pure water (1.0g/ml). Show work here and record your answer in Data Table 2. 3. Calculate the total heat released in each reaction, assuming that the specific heat of the solution is the same as for pure water (4.18J/gK). Use q=mcΔT. Show work here and record your answer in Data Table 2. 4. Calculate the number of moles of NaOH used in reactions one and two. Show work here and record your answer in Data Table 2. 5. In reaction three, the number of moles of NaOH can be calculated from the concentration of the solution (1.0M = 1.0mole/L) and the volume used. The calculation is below. Enter the result into Data Table 2. 50.0ml NaOH x 1mol NaOH = 0.050mol NaOH 1 1000ml NaOH 6. Calculate the molar enthalpy in Joules per mole of NaOH for each reaction. Show work here and record your answer in Data Table 2.

Data Table 2: Results of

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