Question

Can someone help me out here? I need help filling in some information.

Answer 1

Data and Observations:
Insert a complete data table, including appropriate significant figures and units, in the space below. Also include any observations that you made over the course of Part I.

Distilled Water Volume
205.0 mL
Mass of NaOH
2.535 g NaOH
Initial temperature in calorimeter
24.2 degrees C
Final temperature in calorimeter
27.8 degrees C





Calculations:
Show your work and write a short explanation with each calculation.
Write out a balanced "equation" for the process you investigated in Part I, including phase symbols.
NaOH + H2O -> NaOH
Calculate the number of moles of sodium hydroxide dissolved. Show your work.
2.535 grams NaOH * (1 mole / 40 grams) = 0.06338 NaOH moles
Calculate the amount of energy involved in this dissolving process. Show your work.
q = m c (T2 - T1)
200 mL H2O * 1 g/1 mL = 200 g H2O
c = 4.184 J/gC
T2 = 27.8 C
T1 = 24.2 C
200 g * 4.18 J/gC * (27.8 - 24.2) = 3010 J = Heat gained by H2O
Determine the enthalpy change, per mole of sodium hydroxide dissolved. Show your work.
3010 J / 0.06338 NaOH moles = 4.75 * 10^4 J/moles * 1 kJ / 1000 J = 47.5 kJ/moles NaOH
The value determined in question 4 is the enthalpy change value you will need for Conclusion question 1 below.


Part II
The Reaction of Sodium Hydroxide Solution with Hydrochloric Acid
Procedure:
Measure out approximately 100 mL of 0.50 M hydrochloric acid solution and 100 mL of 0.50 M sodium hydroxide solution. Record both volumes on your data table.
Pour the hydrochloric acid solution into the calorimeter. Measure and record the initial temperature of each solution and record on your data table.
Add the sodium hydroxide solution to the acid solution in the calorimeter and immediately replace the lid of the calorimeter. Stir the mixture and record the highest temperature reached.
Data and Observations:
Insert a complete data table, including appropriate significant figures and units, in the space below. Also include any observations that you made over the course of Part II.



Volume of HCl solution
105 mL HCl
Volume of NaOH solution
105 mL NaOH
Initial temperature in calorimeter
25.2 degrees C
Final temperature in calorimeter
28.2 degrees C

Calculations:
Write out a balanced equation for the reaction you investigated in Part II, including phase symbols.
HCI + NaOH -> NaCl + H2O
Determine the enthalpy change of this reaction. The mass of the sodium hydroxide and the mass of the hydrochloric acid should be added together.
105 mL HCI + 105 mL NaOH = 210 mL
210 mL * (1 g/mL) = 210 g
210 g * 4.184 j(28.2 - 25.2) = 2475
2475 J * 1 kJ/100 J = 2.475 kJ
Determine the number of moles of NaOH.
105 mL NaOH * 1L NaOH/1000 mL NaOH * 0.105 moles NaOH/1L NaOH = 0.0105 NaOH moles
Determine enthalpy per mole of NaOH. Show all of your work.
2.475 kJ/0.0105 NaOH moles = 235.7 kJ/mol
The value determined in question 4 is the enthalpy change value you will need for Conclusion question 1 below.


Conclusion:
Determine the enthalpy change for NaOH (s) + HCl (aq) -> NaCl (aq) + H2O (l) using Hess's Law.
-425.93 -92.30 -407.27 -285.83
Hess's Law: △H(rxn) = Sum[ △H(f) products] - Sum[ △H(f) reactants]

H(rxn) = [(1 mol)(-407.27 kJ/moles) + (1 mole)(-285.83 kJ/moles)] - [(1 mole)(-425.93 kJ/moles) + (1 mole)(-92.30)] = - 359.47 kj/moles

a. Write the balanced chemical reaction and enthalpy change for Part I (1pt)
NaOH(s)+ H2O(I) -> Na(aq)+ OH-(aq) △H = -49.3kJ/moles

b. Write the balanced chemical reaction and enthalpy change for Part II (1pt)

NaOH(aq) + HCl(aq) -> NaCl(aq) + H2O(I) △H = -1.012kJ/moles

c. Calculate the enthalpy change using Hess's Law. Refer to the lesson for an example
of Hess's Law. (2pt)


If the accepted enthalpy change value for the dissolving of sodium hydroxide in water is -44.2 kilojoules per mole, determine the percent error of the experimental value that you calculated in Part I. Show your work.
(experimental - actual value) / actual value = 100 %

-45.6 - -44.2 / -44.2 = -1.4 / -44.2 = 0.03 * 100 = 3


If the accepted heat of reaction for the neutralization of hydrochloric acid with sodium hydroxide is -56.0 kilojoules per mole, determine the percent error of the experimental value that you calculated in Part II. Show your work.
(experimental - actual value) / actual value = 100 %

-56 - (-1.004) - 54.996/-56 = 0.982 * 100 = 98.2%


Using the accepted values of the processes you've examined, would your estimation of the enthalpy change for the reaction of solid sodium hydroxide in aqueous hydrochloric acid change from the prediction you made in question one? Explain your answer in complete sentences.

Give a detailed explanation, using what you know about bonds and forces of attraction, for the enthalpy changes you observed in parts I and II of this lab. Explain your answer in complete sentences.


If the hole for the thermometer in a calorimeter is wider than the diameter of the thermometer, leaving a gap between the lid and the thermometer itself, how do you think this would this affect the temperature change observed in the experiment? How would this affect the calculated enthalpy change? Explain your answers in detail.