155 PRELAB 10 After answering these questions, enter your answers in Bb attempts
ID: 551821 • Letter: 1
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155 PRELAB 10 After answering these questions, enter your answers in Bb attempts. If for any reason, the system fails, write from the manual and give this to your TA before prelab lecture two paper submission per semester The system has been setup for 2 your answers on this page, tear out the page starts. You are allowed up to The table below indicates how the reactions with be performed in this lab RUNS Run 1 Run 2 Run 3 Run 4 mL of water mLof 0.50 M HCI ml of 1.00 M NaOH 2.00 1.00 0.00 2.00 3.00 4.00 1.00 1.00 1.00 2.00 1.00 2.00 For each of the runs above, calculate the mol of HCl, the mol of Na0H and identify the limiting reagent; mol MxL STA mol NaOH Limiting reagent Post reaction solution acidic or basic? Run 1 Run 2 Run 3 Run 4 Do you expect the enthalpies of reaction from Run 1 to Run 4 to give results that are the same (within experimental) error or do you expect these to different? Explain your reasoning.Explanation / Answer
Run 1:
HCl => 0.50M * 2.00ml/1000ml/L=> 0.001 moles
NaOH=> 1.00M * 1.00 ml/1000ml/L=> 0.001 moles
No limiting reagent in this case as number of moles is same.
Post reaction solution will be neutral. Neither acidic or basic.
Similarly in Run 2:
HCl=> 0.0015 moles
NaOH=> 0.001 moles
NaOH will be the limiting reagent as NaOH has fewer mole.
Post reaction will be acidic due to remaining HCl.
Run 3:
HCl=> 0.002 mol
NaOH=> 0.001 mol
Again NaOH will be limiting reagent because it has fewer moles.
post reaction will be acidic.
Run 4:
HCl=> 0.0005 moles
NaOH=> 0.002 moles
In this case, HCl is the limiting reagent.
Post reaction will be basic as NaOH is in excess.
Enthalpy of reaction depends on the number of moles of reactants reacting. In this experiment, the number of moles reacting is the same in run 1,2 and 3 (0.001 moles) hence enthalpy will be same in run 1,2 and 3. But it will be different in run 4 as number of moles reacting => 0.0005 moles. So enthalpy will also be half of other runs.
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