P untitled docum x C cheg .edubatesalchem220MabMabmanual-sum12/1-factors-sum12.p

Question

P untitled docum x C cheg .edubatesalchem220MabMabmanual-sum12/1-factors-sum12.pdf system C: Concentration and Reaction Rates: Magnesium in HCIsolution Background: In part A, you observed the reaction ofHCI with Mg. Now, you will observe the effect of the HCI concentration on the rate of the reaction. Procedure: Plpet 1ml of 6MHcl,4MHcl, 3MHC, and 2MHCI into four separate labeled small test tubes. mass of each strip. 4) When all traces of the magnesium strip have reacted, record the end time. 5) Repeat the reaction for the other three solutions. Analysis Report: 1) Calculate the moles of HCI, moles ofMg and the mol HCI ratio for each trial, MG 2) Plot mol HCI (y-axis) vs. time in seconds (x-axis). 3) Comment on the effect of the HCl concentration on the reaction time. sierra

Explanation / Answer

The balanced chemical equation for the reaction between Mg and HCl is given as

Mg + 2 HCl ------> MgCl2 + H2

As per the stoichiometric equation,

1 mole Mg = 2 moles HCl.

1)

Prepare the following table.

Trial

Volume of HCl in L

Mole(s) of HCl = (volume of HCl in L)*(concentration of HCl in mol/L) (1 M = 1 mol/L)

Mole(s) of Mg = (mole HCl)*(1 mole Lg/2 mole HCl)

(Mol HCl)/(Mol Mg)

1

1 mL = (1 mL)*(1 L/1000 mL) = 0.001 L

(0.001 L)*(6 mol/L) = 0.006 mole

0.006/2 mole = 0.0003 mole

(0.006 mole)/(0.003 mole) = 2

2

1 mL = (1 mL)*(1 L/1000 mL) = 0.001 L

(0.001 L)*(4 mol/L) = 0.004 mole

0.004/2 mole = 0.002 mole

(0.004 mole)/(0.002 mole) = 2

3

1 mL = (1 mL)*(1 L/1000 mL) = 0.001 L

(0.001 L)*(3 mol/L) = 0.003 mole

0.003/2 mole = 0.0015 mole

(0.003 mole)/(0.0015 mole) = 2

4

1 mL = (1 mL)*(1 L/1000 mL) = 0.001 L

(0.001 L)*(2 mol/L) = 0.002 mole

0.002/2 mole = 0.001 mole

(0.002 mole)/(0.001 mole) = 2

2) Prepare the following table.

Trial

(mole HCl)/(mole Mg)

Time in s

1

2

24

2

2

42.91

3

2

63

4

2

104

Plot the data on a graph

Plot of (mole HCl)/(mole Mg) vs t

3) Note that the graph is a straight line parallel to the time axis. This means that the rate of the reaction is independent of the concentration of HCl. Hence, changing the concentration of HCl will have no effect on the rate of the reaction.

Trial

Volume of HCl in L

Mole(s) of HCl = (volume of HCl in L)*(concentration of HCl in mol/L) (1 M = 1 mol/L)

Mole(s) of Mg = (mole HCl)*(1 mole Lg/2 mole HCl)

(Mol HCl)/(Mol Mg)

1

1 mL = (1 mL)*(1 L/1000 mL) = 0.001 L

(0.001 L)*(6 mol/L) = 0.006 mole

0.006/2 mole = 0.0003 mole

(0.006 mole)/(0.003 mole) = 2

2

1 mL = (1 mL)*(1 L/1000 mL) = 0.001 L

(0.001 L)*(4 mol/L) = 0.004 mole

0.004/2 mole = 0.002 mole

(0.004 mole)/(0.002 mole) = 2

3

1 mL = (1 mL)*(1 L/1000 mL) = 0.001 L

(0.001 L)*(3 mol/L) = 0.003 mole

0.003/2 mole = 0.0015 mole

(0.003 mole)/(0.0015 mole) = 2

4

1 mL = (1 mL)*(1 L/1000 mL) = 0.001 L

(0.001 L)*(2 mol/L) = 0.002 mole

0.002/2 mole = 0.001 mole

(0.002 mole)/(0.001 mole) = 2

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