A mixture of hydrogen and oxygen gas shows no apparent reaction at room temperat

Question

A mixture of hydrogen and oxygen gas shows no apparent reaction at room temperature, yet it explodes when a match is lit. What is the correct explanation for this observation?

a)Water is more stable than molecular hydrogen and oxygen at room temperature.

b)Unless the concentrations of hydrogen and oxygen are 2:1 respectively, no reaction occurs.

c)The reaction is exothermic at higher temperatures, but endothermic at room temperature.

d)The activation energy for this reaction is so high that there is not enough thermal energy at room temperature for reaction to occur.

Explanation / Answer

a) Water is more stable than molecular hydrogen and oxygen at room temperature. False

b) Water is more stable than molecular hydrogen and oxygen at room temperature.True

Sources of helium, hydrogen and oxygen should be available. The blue balloons are filled with helium, tied off and attached to the strings attached to weights - plastic balloon closures can be used to attach the balloons to the strings. The yellow balloons are filled with hydrogen, and the red balloons are filled with a 2:1 mixture of hydrogen and oxygen

c) The reaction is exothermic at higher temperatures, but endothermic at room temperature. False

ignition temperature is ca. 580 °C. The gaseous reaction is 2 H2(g) + O2(g) 2 H2O(g)

This exothermic reaction yields 232 kJ/mol of water formed,hydrogen (H2) will not react with oxygen (O2) at room temperature; however

d) The activation energy for this reaction is so high that there is not enough thermal energy at room temperature for reaction to occur .True

Only when more energy is added does reaction take place at a measurable rate.

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