A sample of hydrogen gas was collected over water at 21° C and 685 mm Hg. The volume of the container was 7.80 L. Calculate the mass of H2(g) collected (vapour pressure of water =18.6 mm Hg at 21° C )

Question

A sample of hydrogen gas was collected over water at 21° C and 685 mm Hg. The volume of the container was 7.80 L. Calculate the mass of H2(g) collected (vapour pressure of water =18.6 mm Hg at 21° C ) (A) 0.283 g (B) 0.570 g (C) 0.589 g (D) 7.14 g

Tardigrade Admin · Accepted Answer

The volume of H2 at STP V2=(P1 V1/T1) × (T2/P2) Here vapour pressure of H2 at 21° C =685 mm -18.6 mm =666.4 mm So V 2=(666.4 mm Hg × 7.80 L × 273 K /294 K × 760 mm )=6.38 L At STP 22.4 L H 2 weight =2 g So, at STP 6.38 L H 2 weigh =(2 g × 6.38 L /22.4 L )=0.570 g

Q. A sample of hydrogen gas was collected over water at 21∘C and 685mmHg. The volume of the container was 7.80L. Calculate the mass of H2​(g) collected (vapour pressure of water =18.6mmHg at 21∘C )

0.283 g

0.570 g

0.589 g

7.14 g

The volume of H2​ at STP V2​=T1​P1​V1​​×P2​T2​​ Here vapour pressure of H2​ at 21∘C =685mm−18.6mm=666.4mm So V2​=294K×760mm666.4mmHg×7.80L×273K​=6.38L At STP 22.4LH2​ weight =2g So, at STP 6.38LH2​ weigh =22.4L2g×6.38L​=0.570g

Q. A sample of hydrogen gas was collected over water at $2 1^{\circ} C$ and $685 mm H g$ . The volume of the container was $7.80 L$ . Calculate the mass of $H_{2} (g)$ collected (vapour pressure of water $= 18.6 mm H g$ at $2 1^{\circ} C$ )