Question

15cm3 of hydrogen are sparked with 10cm3bof oxygen at atmospheric pressure. What is the total volume of the residual gas at room temperature.

Answer 1

#83858 Chemistry, Other

$15~\mathrm{cm}^3$ of hydrogen are sparked with $10~\mathrm{cm}^3$ of oxygen at atmospheric pressure. What is the total volume of the residual gas at room temperature.

Answer:

$$2 \mathrm {H} _ {2} + \mathrm {O} _ {2} \rightarrow 2 \mathrm {H} _ {2} \mathrm {O}$$ $$n = V / 22.4$$ $$n = m / M$$ $$n \left(H _ {2}\right) = 1 5 / 2 2. 4 = 0. 7 \text { mmol}$$ $$n \left(O _ {2}\right) = 1 0 / 2 2. 4 = 0. 5 \text { mmol}$$

According to equation above, $n(H_2) = 2 \times n(O_2)$ or $n(O_2) = n(H_2) / 2$ . Therefore, Hydrogen will react fully. The remaining amount of $O_2$ will be:

$$n \left(O _ {2}\right) = 0. 5 - (0. 7 / 2) = 0. 1 5 \text { mmol}$$ $$V \left(O _ {2}\right) = 0. 1 5 \times 2 2. 4 = 3. 3 6 \mathrm {c m} ^ {3}$$

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