Magnesium reacts with HCl to produce magnesium chloride and hydrogen gas.
Mg(s)+2HCl(aq)->MgCl2(aq)+H2(g).
What is the molarity of the HCl solution if 330 ml of the HCl solution reacts with magnesium to produce 7.40 L of H2 gas measured at STP?
7.40 L H2 gas @ STP = 7.40/22.4 = moles H2 @ STP.
moles HCl = moles H2 x (2 moles HCl/1 mole H2) = ??moles H2 x 2 = xx moles HCl
Then M HCl = mols HCl/L HCl
You have moles and L, solve for M.
To find the molarity of the HCl solution, we need to use the balanced chemical equation and the stoichiometry of the reaction.
First, let's convert the volume of H2 gas produced from liters to moles. We can use the ideal gas law at STP, which states that 1 mole of any gas occupies 22.4 liters at standard temperature and pressure.
Given:
Volume of H2 gas (V) = 7.40 L
Using the ideal gas law:
n = V / Vm
where n is the number of moles, V is the volume of the gas, and Vm is the molar volume at STP (22.4 L/mol).
n = 7.40 L / 22.4 L/mol
n = 0.330 mol
According to the balanced chemical equation, the reaction between 2 moles of HCl and 1 mole of Mg produces 1 mole of H2 gas. Therefore, the number of moles of HCl that reacted with the Mg is also 0.330 mol.
Now, let's calculate the molarity of the HCl solution.
Molarity (M) is defined as the number of moles of solute per liter of solution. In this case, the solute is HCl.
Molarity = moles of solute (HCl) / volume of solution (in liters)
Given:
Volume of HCl solution used = 330 mL = 0.330 L (remember to convert to liters)
Molarity = 0.330 mol / 0.330 L
Molarity = 1.00 M
Therefore, the molarity of the HCl solution is 1.00 M.