Question

Last week you reacted magnesium with a hydrochloric acid aqueous solution and hydrogen gas was produced. Let's say that you collected the gas given off by the reaction and measured it's pressure as 101.2 kPa. If the vapor pressure of water is 31.4 kPa at this temperature, then what is the pressure of the hydrogen gas?

Answer 1

Answer:

69.8 kilo Pasacl is the pressure of the hydrogen gas.

Explanation:

$Mg+2HCl\rightarrow MgCl_2+H_2$

Pressure at which hydrogen gas collected = p = 101.2 kilo Pascals

Vapor pressure water = $p^o$ = 31.4 kilo Pascals

The pressure of hydrogen gas = P

The pressure at which gas was collected was sum of vapor pressure of water and hydrogen gas.

$p=P+p^o$

$P =p-p^o=101.2 kPa-31.4 kPa=69.8 kPa$

69.8 kilo Pasacl is the pressure of the hydrogen gas.