Final answer:
To determine the pressure of hydrogen gas formed in mmHg, use the ideal gas law equation and the balanced chemical equation for the reaction. Plug in the known values and solve for the pressure of hydrogen gas.
Step-by-step explanation:
To determine the pressure of hydrogen gas formed in mmHg, we first need to know the total pressure of gas collected. In this reaction, magnesium (Mg) reacts with hydrochloric acid (HCl) to produce magnesium chloride (MgCl₂) and hydrogen gas (H₂).
The balanced equation for this reaction is: Mg(s) + 2HCl(aq) --> MgCl₂(aq) + H₂(g).
Since the reaction produces only one mole of hydrogen gas for every mole of magnesium reacted, we can calculate the pressure of hydrogen gas using the ideal gas law equation: PV = nRT.
In this case, the only unknown is the pressure of hydrogen gas (P), so we can rearrange the equation to solve for P.
Given the total pressure of gas collected over water as 725.0 mmHg and a temperature of 23.0 °C, we can calculate the pressure of hydrogen gas.
P = (nRT) / V