Ex 8

‫بسم ال الرحمن الرحيم‬ Name: ayedzahran Group: Day:

Experiment 9 "Stoichiometry of two chemical reaction" __________________________________________________________________ I. Observations and results: A. Reaction between HCl and NaOH: Table 1 ml 1 M HCl 5 10 15 20 25 30 35 40 45

ml 1 M NaOH 45 40 35 30 25 20 15 10 5

Temperature change 25-24=1 Cº 25-23.5=1.5 Cº 25.5-22.5=2 Cº 26-23=3 Cº 27-23=4 Cº 26-22.5=3.5 Cº 24-22=2 Cº 22.5-21.5=1 Cº 22-21.5=0.5 Cº

B. Reaction between H2SO4 and NaOH Table 2 ml 1 M H2SO4 5 10 15 20 25 30 35 40 45

ml 1 M NaOH 20 20 20 20 20 20 20 20 20

Temperature change Cº 30.5-23=7.5 Cº 10.5=33.5-23 Cº 9.5=33-23.5 Cº 9=32-23 Cº 8=31-23 Cº 7.5=30.5-23 Cº 6.5=29.5-23 Cº 6=29-23 Cº 5.5=28-22.5

III. Answer the following questions: 1. If a substantial amount of heat is lost to the surroundings, how will this affect the experimental value of each of Hccal and determined ΔH? Explain your answer If a substantial amount of heat is lost to the surroundings the equation will be Qhw=Qcw+Qcal+Qsurrounding , that’s mean the amount of heat of hot water will goes to cold water, calorimeter and surrounding, but we can't account the amount of heat of surrounding so that we will consider the equation is Qhw=Qcw+Qcal , then the ΔH will be less than the actual amount (decrease), the analyze of equation is : Spwater *mhwater* (Th-Tf) = Spwater * mcwater * (Tf-Tc) + Hccal* ΔT2 and Hccal = Spwater *mhwater* (Th-Tf) - Spwater * mcwater * (Tf-Tc) / (Tf-Tc) = Spwater (mhwater* (Th-Tf) - mcwater* (Tf-Tc))/ (Tf-Tc) Th , Tc , mhwater , mcwater & Spwater is constant Tf decrease so that Th-Tf increase & Tf-Tc decrease, so the Hccal will increase 2. Why is it necessary for all components to be at room temperature at the beginning at the experiment Because the temperature is the most part are necessary in this experiment and when we change any of surroundings at the beginning or final of experiment (especially temperature) the numbers of the experiment will change, that’s will happen if the temperature of room change after starting the experiment

Not: For experiment number, For calculation number, For the solution of answers.