# What mass of hydrogen gas is produced when a 7.43 g chunk of zinc dissolves in 500.0 mL of 1.200M HCl?

## This is a limiting reagent (LR) problem. You know that when an amount for BOTH reactants is given.

Zn + 2HCl ==> H2 + ZnCl2

mols Zn = grams/molar mass.

mols HCl = M x L = ?

Using the coefficients in the balanced equation, convert mols Zn to mols H2.

Do the same for mols HCl to mols H2.

It is likely that the two values for mols Zn will not agree which means one of them is wrong; the correct value in LR problems is ALWAYS the smaller value and the reagent producing that value is the LR.

Using the smaller value of mols H2, convert to grams. g = mols x molar mass.

## For my problem, grams of Zn = 7.77

Zn(s) + 2HCl(aq) --> H2(g) + ZnCl2(aq)

1.2 M HCl = x/0.5 L. x = 0.6 mol HCl

7.77g / 65.38 (molar mass) = 0.1188 mol Zn

mols Zn -> H2

0.1188 * (1/1) = 0.1188

mols HCl -> H2

0.6 * (1/2) = 0.3

0.1188 * 2.02(molar mass of H2) =

0.239976 g

## To find the mass of hydrogen gas produced, we need to use the balanced chemical equation for the reaction between zinc and hydrochloric acid.

The balanced equation is:

Zn + 2 HCl -> ZnCl2 + H2

From the equation, we can see that for every 1 mole of zinc that reacts, 1 mole of hydrogen gas is produced.

To find the moles of hydrogen gas produced, we first need to calculate the moles of zinc using its molar mass.

The molar mass of zinc (Zn) is 65.38 g/mol.

Moles of zinc = mass of zinc / molar mass of zinc

Moles of zinc = 7.43 g / 65.38 g/mol

Moles of zinc = 0.1136 mol

Since the reaction is 1:1 between zinc and hydrogen gas, the moles of hydrogen gas produced will also be 0.1136 mol.

To calculate the mass of hydrogen gas, we need to use its molar mass.

The molar mass of hydrogen (H2) is 2.02 g/mol.

Mass of hydrogen gas = moles of hydrogen gas x molar mass of hydrogen gas

Mass of hydrogen gas = 0.1136 mol x 2.02 g/mol

Mass of hydrogen gas = 0.2297 g

Therefore, the mass of hydrogen gas produced when a 7.43 g chunk of zinc dissolves in 500.0 mL of 1.200M HCl is approximately 0.2297 g.

## To find the mass of hydrogen gas produced when zinc reacts with hydrochloric acid, we need to use stoichiometry and balanced chemical equation. The balanced chemical equation for the reaction between zinc and hydrochloric acid is:

Zn(s) + 2HCl(aq) → ZnCl2(aq) + H2(g)

From the balanced chemical equation, we can see that 1 mole of zinc reacts with 2 moles of hydrochloric acid to produce 1 mole of hydrogen gas.

Step 1: Calculate the number of moles of zinc:

To find the moles of zinc, we can use the molar mass of zinc, which is 65.38 g/mol.

molar mass of zinc = 65.38 g/mol

moles of zinc = mass of zinc / molar mass of zinc

= 7.43 g / 65.38 g/mol

Step 2: Calculate the number of moles of hydrogen gas produced:

From the balanced equation, we know that the stoichiometric ratio between zinc and hydrogen gas is 1:1. Therefore, the moles of hydrogen gas produced will be the same as the moles of zinc.

moles of hydrogen gas = moles of zinc

Step 3: Convert moles to grams:

To find the mass of hydrogen gas, we can use the molar mass of hydrogen, which is 2.016 g/mol.

molar mass of hydrogen = 2.016 g/mol

mass of hydrogen gas = moles of hydrogen gas × molar mass of hydrogen

= moles of zinc × molar mass of hydrogen

Now, since we have calculated moles of zinc in step 1, we can calculate the mass of hydrogen gas.

mass of hydrogen gas = (7.43 g / 65.38 g/mol) × 2.016 g/mol

By substituting the values into the above equation and performing the calculation, we can find the mass of hydrogen gas produced.