Question

21° + H2O2 + H 2 + H2O by varying reactant concentrations and reaction temperature. Results 40.0 40.0 40.0 40.0 10.0 10.0 10.0 5.0 10.0 20.0 20.0 10.0 0.0 30.0 5.0 30.0 Flask Number Volume of buffered Iodide solution (mL) Volume of Thiosulfate solution (mL) Volume of water (mL) Volume of Peroxide solution (mL) Total Volume (mL) Stop Time (seconds) Start Time Total Time(seconds) Initial Temperature (°C) Final Temperature (°C) 80.0 587 80.0 1085 80.0 419 80.0 1316 587 419 1316 1085 23 23 23 23

using the data above answer 6-8

the stock solution of H2O2 was 0.2M

Answer 1

6. Stock solution of H2O2 has the concentration 0.2 M.

	Trial 1	Trial 2	Trial 3	Trial 4
Volume of H2O2 stock solution taken (mL)	20	10	30	30
Total volume (mL)	80	80	80	80
initial [H2O2] (M)	0.0500	0.0250	0.0750	0.0750

We will use the formula for dilution to calculate initial concentration of H2O2,i.e. [H2O2].

V1 S1 = 125

where, V1= initial volume of H2O2

  V2= final volume of H2O2 = total volume (here)

S1= initial concentration of H2O2

S2= initial concentration of H2O2

For trial-1:

V1 S1 = 125

or,

20 x 0.2 = 80 x S

or,

S2 = -= 0.05M 80

Calculate similarly for trial-2 to trial 4:

Trial 2:

S2 = = 0.025M 80

Trial 3:

S2= 30 x 0.2 -= 0.075M 80

Trial 4:

S2= 30 x 0.2 -= 0.075M 80