Calculate the amount of H2 produced from the reaction of 4.25 grams Zn and 25 ml of 3.0 M HCL.
This is a limiting reagent (LR) problem.
Zn + 2HCl ==> H2 + ZnCl2
mols Zn = grams/atomic mass = ?
mols HCl = M x L = ?
Using the coefficients in the balanced equation, convert mols Zn to mols H2.
Do the same to convert mols HCl to mols H2.
More than likely the two values for mols H2 produced will not be the same which means one of the values is not right. The correct value in LR problems is ALWAYS the smaller one and the reagent producing that value is the LR.
Take the smaller value of mols H2 produced and convert it to grams. g H2 = mols H2 x molar mass H2.
What was wrong with the solution I posted on this same problem? => Tuesday, April 18, 2017 at 9:35pm
To calculate the amount of H2 produced from the reaction of Zn (Zinc) and HCl (Hydrochloric acid), we need to follow a few steps:
Step 1: Write the balanced chemical equation for the reaction:
Zn (s) + 2HCl (aq) → ZnCl2 (aq) + H2 (g)
According to the equation, 1 mole of Zn reacts with 2 moles of HCl to produce 1 mole of H2.
Step 2: Convert the mass of Zn to moles:
The molar mass of Zn is approximately 65.38 g/mol.
Using the formula: moles = mass / molar mass, we can calculate the number of moles of Zn.
moles of Zn = 4.25 g / 65.38 g/mol ≈ 0.065 moles Zn
Step 3: Determine the limiting reactant:
To find the limiting reactant, we must compare the moles of Zn and HCl used in the reaction.
From the balanced equation, we see that 1 mole of Zn reacts with 2 moles of HCl.
So, the number of moles of HCl required for the reaction = 2 × 0.065 moles ≈ 0.13 moles HCl
However, we also need to convert the volume of the HCl solution to moles.
The molarity (M) of HCl is given as 3.0 M, which means there are 3 moles of HCl in 1 liter (1000 ml) of solution.
Using the formula: moles = concentration (M) × volume (L), we can calculate the number of moles of HCl.
moles of HCl = 3.0 M × 0.025 L = 0.075 moles HCl
Comparing the moles of Zn and HCl, we see that we have 0.065 moles of Zn and 0.075 moles of HCl. Since we use equal or fewer moles of Zn, Zn is the limiting reactant.
Step 4: Calculate the amount of H2 produced:
From the balanced equation, we know that 1 mole of Zn produces 1 mole of H2.
So, the number of moles of H2 produced = moles of Zn = 0.065 moles
Step 5: Convert moles of H2 to grams:
The molar mass of H2 is approximately 2.02 g/mol.
Using the formula: mass = moles × molar mass, we can calculate the mass of H2.
mass of H2 = 0.065 moles × 2.02 g/mol ≈ 0.1313 grams
Therefore, the amount of H2 produced from the reaction is approximately 0.1313 grams.