Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
If 2.00 g of Mg reacts completely with 50.0 mL of HCl solution, what is the molarity of the HCl solution?
One needs twice the number of moles of HCl as Mg.
how many moles of Mg is there in 2g?
moles of HCL=twiceMolesMg=.050*Molarity
solve for molarity
To find the molarity of the HCl solution, we need to use the given information and stoichiometry of the reaction.
1. Convert the mass of Mg to moles:
Using the molar mass of Mg (24.31 g/mol), calculate the moles of Mg:
2.00 g / 24.31 g/mol = 0.0823 mol
2. Convert the volume of HCl solution to liters:
Convert mL to L by dividing by 1000:
50.0 mL = 50.0 mL / 1000 mL/L = 0.0500 L
3. Use the balanced chemical equation to determine the mole ratio between Mg and HCl:
From the balanced equation: 1 mole of Mg reacts with 2 moles of HCl.
4. Calculate the moles of HCl reacted:
Since 1 mole of Mg reacts with 2 moles of HCl, the moles of HCl will be twice the moles of Mg:
0.0823 mol of Mg × 2 = 0.1646 mol of HCl
5. Calculate the molarity of the HCl solution:
Molarity (M) is defined as moles of solute divided by volume of solution in liters.
Molarity = moles of solute / volume of solution (in liters)
Molarity = 0.1646 mol / 0.0500 L = 3.29 M
Therefore, the molarity of the HCl solution is 3.29 M.
To find the molarity of the HCl solution, we first need to determine the number of moles of HCl that reacted with the 2.00 g of Mg.
Step 1: Calculate the number of moles of Mg.
To do this, we need to know the molar mass of Mg, which is 24.31 g/mol.
Using the formula: moles = mass / molar mass,
we can calculate the number of moles of Mg:
moles of Mg = 2.00 g / 24.31 g/mol = 0.0823 mol
Step 2: Use the balanced chemical equation to determine the mole ratio between Mg and HCl.
From the balanced equation, we can see that the mole ratio between Mg and HCl is 1:2. This means that for every 1 mole of Mg, 2 moles of HCl are required.
Step 3: Calculate the number of moles of HCl.
Since the mole ratio is 1:2, the number of moles of HCl can be calculated by multiplying the number of moles of Mg by the mole ratio:
moles of HCl = 0.0823 mol * 2 = 0.1646 mol
Step 4: Find the volume of the HCl solution in liters.
The given volume of HCl solution is 50.0 mL. However, to use in the molarity calculation, we need to convert it to liters:
volume of HCl in liters = 50.0 mL * (1 L / 1000 mL) = 0.0500 L
Step 5: Calculate the molarity of the HCl solution.
The molarity (M) is defined as the number of moles of solute per liter of solution. In this case, the solute is HCl and the solution volume is 0.0500 L:
molarity of HCl = moles of HCl / volume of HCl in liters = 0.1646 mol / 0.0500 L = 3.29 M
Therefore, the molarity of the HCl solution is 3.29 M.