26. (6pts) One method of determining the concentration of hydrogen peroxide (HHa

Question

26. (6pts) One method of determining the concentration of hydrogen peroxide (HHao2) in a solution is through titration with the iodide ion. The net ionic equation for this reaction is H202 21- +2H* 2H20 A 50.00 mL sample of a hydrogen peroxide solution is found to react completely with 37.12 mL of a 0.1500 M KI solution. What is the concentration of hydrogen peroxide in the sample? A. 0.1010 M 568 x 10-2 M 0.4041 M D. 0.1 114 M E. 22.27 M el136 27. (2 pts) Which of the following represents a combustion reaction? C.202He (g) 7O2 (g) 4CO2 (g) 6H20() E LioH (aq) HNO3(aq) LiNO3(aq) Hao (l)

Explanation / Answer

26.

Nuber of milimoles of KI = molarity x volume (mL) = 0.1500 x 37.12 = 5.568 mmol

From the balanced equation:

2 mol of KI reactc with 1 mol of H2O2

So, 5.568 mmol would have reacted with: (1/2) x 5.568 mmol of H2O2 = 2.784 mmol

Molarity = number of mmol of H2O2 /volume (mL) = 2.748/50.00 = 5.568 x 10-2 M

27.

In a combustion reaction, a substance is reacted with O2 molecule. So, option C is correct.

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