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30cm3 pf hydrogen at s.t.p combine with 20cm3 of oxygen t...

30cm3 pf hydrogen at s.t.p combine with 20cm3 of oxygen to form steam according to the following equation 2H2(g) + O2(g) → 2H2O(g).

Calculate the total volume of the gaseous mixture at the end of the reaction

A.

50cm3

B.

35cm3

C.

30cm3

D.

25cm3

Correct answer is B

2H\(_2\)(g) + O\(_2\)(g) → 2H\(_2\)O(g).


2 volumes of H\(_2\)(g) and 1 volume of O\(_2\)(g) produced 2 volumes of H\(_2\)O\(_2\)

ratio of reacting volumes

30cm\(^3\) + 15cm\(^3\) → 30cm\(^3\)

30cm\(^3\) of Hydrogen requires 15cm\(^3\) of oxygen to produce 30cm\(^3\) of water.

Excess oxygen: 20cm\(^3\) – 15cm\(^3\) = 5cm\(^3\)

Total volume of gaseous mixture: 5cm\(^3\) of Oxygen + 30cm\(^3\) of Water = 35cm\(^3\)