Hydrogen is collected over water at 19C and 785 mmHg of pressure. THe total volume of the sample was 1.93L How do you calculate the volume of hydrogen at STP?
The volume of hydrogen is 1.84 L.
This is an example of a Combined Gas Laws problem.
#color(blue)(|bar(ul((P_1V_1)/T_1 = (P_2V_2)/T_2|)#
We can rearrange this formula to get
#V_2 = V_1 × P_1/P_2 × T_2/T_1#
The vapour pressure of water at 19 °C = 16.5 mmHg.
∴ The pressure of the dry hydrogen is given by
Your data are then:
The volume is 1.84 L.