Question

need help with calculations

V. Heat of reaction for NaOH (s) + HCI (aq) → Naci (aq) + H20 ()-dH(net) Direct determination Mass NaOH Moles NaOH = moles Mass of HCI solution Final temp. of solution Initial temp. of solution AT solution 30 23 C 4 C AH(net)(Direct) per mole NaOH Calculation Indirect determination Heat of dissolution of NaOH (s) [AH(diss)] Mass NaOH Moles NaOH moles Mass of water Final temp. of solution Initial temp. of solution AT solution AH(diss)- 30 又91c 22- Fnel Tem AH(diss) per mole NaOH Calculation: V Enthalpy of Reaction: Hess's Lavw In this experiment, the reaction between solid sodium hydroxide and hydrochloric acid will be performed in two different ways. However, since the overall reaction will be the same in each case, the enthalpy change in the two reactions should be the same. This is an example of Hess's Law, which states: 'If a process occurs in stages, or steps, the enthalpy change for the overall process is the summation of the enthalpy changes for the individual steps. The overall, or net reaction, in this experiment is: NaOH (s) + HCl (aq) → NaCl (aq) + H,0 (1) The enthalpy change. AlH(net), can be determined for the direct reaction of solid sodium hydroxide and hydrochloric acid. Another. less direct way of performing this reaction is to form an aqueous solution of sodium hydroxide, then allow that solution to react with hydrochloric acid. NaOH(s) → NaOH (aq) NaOH (a)HCI (aq)NaCI (aq)+H,O ) The enthalpy change for the overall reaction, AH(net) will be given by adding the enthalpy change each step. In both cases the net reaction is the same, therefore the enthalpy change should be the same. Procedure Direct determination of heat of reaction forNaOH (s)±HCl (aq)--NaCl (aq) +H0φ 1. Using a graduated cylinder, measure 30 ml of 1.0 M HC1, then pour the HCl into a 2. Weigh approximately 1,0g solid NaOH to the nearest 0.01 g small Styrofoam cup. Measure the temperature of the HCI solution to the nearest o.IC Once the initial temperature of the HCI solution has been measured, pour the solid NaOH into the HCI solution in the cup. Stir gently with the thermometer, and observe the temperature. Record the final temperature when it stops changing. Ensure all the NaOH has dissolved. This is the final temperature. 3 3. 4. Dispose of the neutralized solution in the cup. by pouring it down the drain. Calculation Determine the enthalpy change for the process per mole of NaOH as in part III. The mass of water will be 30 g cthe mass of solid NaOH in the final solution will be ignored). This enthalpy change is dH(net) for the overall reaction. Indirect determination of heat of reaction for N aOH (s)thici (aq) → Naa (aq) thou) Heat of solution of NaOH (s) Using a graduated cylinder, measure 30 ml of distilled water, then pour the water into Styrofoam cup. Mcasure the temperature of the water to the nearest 0.1"c mately 1.0 g solid NaOH to the nearest 0.0lg o2 1 e initial temperature of the water has been measured. pour the solid NaOH 1. Once the into the temperature. NaOH has dissolved. This is the final temperature. be used in the next step. q water in the cup. Stir gently with the thermometer, and observe the Record the final temperature when it stops changing. Ensure all the Do not discard this solution. It will Calculation Determine the heat of solution of per mole of NaOH in a way similar to that used in part II Heat of neutralization of NaOH () Using a graduated cylinder, measure 30 ml of 1.0 M HCI, Measure the temperature of the lici solution to the nearest 0.1℃ :23°C Measure the temperature of the NaOH solution prepared above. Ensure the temperature of the HCI and NaOH solutions are within I'C, You may need to allow the NaOH solution to cool. > 1. /he-kl 26 C 2. Once the initial temperature of the HCl and NaOH solutions are similar, record the temperature, then pour the HCI solution into the Styrofoam cup containing the NaOH solution. Stir gently with the thermometer, and observe the temperature. Record the temperature when is stops changing. This is the final temperature. 3 Dispose of the neutralized solution in the cup, by pouring it down the drain. 3. 4. Calculations Determination of the enthalpy of neutralization of the NaOH solution (per mole of NaOH) is similar to the calculation used in part III. Verification of Hess' Law The heat of neutralization of solid NaOH with HCI (aq) (AH(net)) should be the same as the sum of the heat of dissolution of solid NaOH (AHdiss) plus the heat of neutralization of aqueou NaOH (AH(neut) H(net)-AH(diss)+AH(neut) 72

Answer 1

ⓘ Given . Mass of HCl - 30 g Findl temp (T2), 37℃ Initial temp (Ti)- 23 c 2.2 37-23-14 le kro that 30 x 4.lgV3℃x (37.23 30x4.18 x 14 .1755-6 J. tvern Mass of Na0Це 30g Fhal temp CT2) 29 Initial temp (T): 22℃ 23 AT * 5928.3 J.