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2NaNO3 → 2NaNO2 + O2. From the equation above, what ...

2NaNO3 → 2NaNO2 + O2. From the equation above, what is the volume of oxygen produced at s.t.p. when 8.5g of 2NaNO3 is heated until no further gas is evolved? (2NaNO3 = 85, molar volume of gases at s.t.p. = 22.4dm3)

A.

1.12dm3

B.

2.24dm3

C.

4.48dm3

D.

11.2dm3

E.

22.4dm3

Correct answer is A

85g of 2NaNO3 will liberated 22.4dm3

8.5g = xdm3

cross multiply: x = [8.5 * 22.4] / 85

x = 2.24dm3

: 8.5g of  2NaNO3 = 2.24dm3

where 2moles of NaNO3 liberates 1mole of O2

2.24dm3 of NaNO3 liberates 1.12dm3 of O2