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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

2H2(g) + O2(g) → 2H2O(g).


2 volumes of H2(g) and 1 volume of O2(g) produced 2 volumes of H2O2

ratio of reacting volumes

30cm3 + 15cm3 → 30cm3

30cm3 of Hydrogen requires 15cm3 of oxygen to produce 30cm3 of water.

Excess oxygen: 20cm3 – 15cm3 = 5cm3

Total volume of gaseous mixture: 5cm3 of Oxygen + 30cm3 of Water = 35cm3