consider the following reaction: Mg(s)+ 2HCl(aq) --> MgCl2 (aq)+H2 (g)
What minimum amount of 1.75 M HCl is necessary to produce 27.5 L of H2 at STP?
Convert 27.5 L H2 at STP to moles. L/22.4 = moles.
Using the coefficients in the balanced equation, convert moles H2 to moles HCl.
M = moles/L. Convert moles HCl to L.
this isnt the right way. i used this way and i got a different asnwer
To determine the minimum amount of 1.75 M HCl required to produce 27.5 L of H2 at STP, we need to use the stoichiometry of the reaction. Let's break down the steps to solve this problem:
Step 1: Write a balanced chemical equation
The balanced chemical equation given is:
Mg(s) + 2HCl(aq) → MgCl2(aq) + H2(g)
Step 2: Determine the stoichiometry ratios
According to the balanced chemical equation, for every 1 mol of Mg, 2 mol of HCl is required to produce 1 mol of H2. The stoichiometric ratio is 1:2:1 (Mg:HCl:H2).
Step 3: Convert the volume of H2 to moles at STP
Using the ideal gas law, we can convert the given volume of H2 at STP (27.5 L) into moles. Since STP conditions are 1 atm and 273 K, we can use the following conversion factors:
1 mole of any ideal gas at STP = 22.4 L
27.5 L H2 × (1 mol H2 / 22.4 L H2) = 1.23 mol H2
Step 4: Calculate the required moles of HCl
Since the stoichiometric ratio is 2 mol of HCl per 1 mol of H2, we need double the amount of moles of H2 to get the required moles of HCl:
1.23 mol H2 × 2 = 2.46 mol HCl
Step 5: Calculate the required volume of the 1.75 M HCl solution
Now, we need to convert the moles of HCl to the volume using the molarity (M) of the HCl solution.
Molarity (M) = moles of solute / volume of solution (in liters)
1.75 M = 2.46 mol HCl / x L HCl
Solving for x (volume):
x = 2.46 mol HCl / 1.75 M
x ≈ 1.41 L
Therefore, approximately 1.41 liters of 1.75 M HCl solution is the minimum amount needed to produce 27.5 L of H2 at STP.