Answer to Question #90529 in General Chemistry for alex

Question

when 20.0 grams of calcium reacts with hydrochloric acid, hydrogen gas is collected at 350 kelvin and 2.5 atmospheres. what is the volume of the hydrogen gas

Answer 1

2.5 atm = 253313 Pa

The following reaction occurs:

$Ca \ + \ 2HCl \ = \ CaCl_2 \ + \ H_2\uparrow$

First calculating amount of calcium given:

$n(Ca)=\frac{m(Ca)}{M(Ca)}=\frac{20.0g}{40\frac{g}{mol}}=0.5mol$

The same amount of hydrogen gas will be evolved: n(H₂)=n(Ca)=0.5 mol

Using ideal gas law pV=nRT we can find volume of the hydrogen:

$V(H_2)=\frac{n(H_2)RT}{p(H_2)}=\frac{0.5mol \cdot 8.314 \frac{J}{mol \cdot K} \cdot 350K}{253313Pa}=0.00574 m^3=5.74L$