What mass in grams of #"HCl"# reacts completely with #"3.208 g Pb"# in the following reaction?

Question

#"Pb(s) + 2HCl"##rarr##"PbCl"_2("aq") + "H"_2("g")"#

Caleb Adams · Accepted Answer

Starting with a balanced equation, you can use the coefficients in front of the formulas to find the mole ratios of the reactants and products. You’ll need to use the molar mass of lead (its atomic weight on the periodic table expressed in g/mol) to convert the mass of lead (Pb) into moles of lead. Once you know how many moles of lead reacted with the HCl, you can use the mole ratio between Pb and HCl and the molar mass of HCl to find the mass of HCl that would react completely with the given mas of Pb.

Balanced equation: #"Pb(s")# + #"2HCl(aq")# #rarr# #"PbCl"_2("aq")# + #"H"_2("g")#

The mass of Pb is 3.208 g. The molar mass of Pb is 207.2 g/mol. The molar mass of HCl is equal to (1 x 1.00794) + (1 x 35.453) = 36.461 g/mol. The mole ratio of Pb to HCl is 1 mol Pb: 2 mol HCl.

Resolution.

Using the molar mass of Pb, convert the mass of Pb to moles.

Number "3.208 g Pb" x Number "1 mol Pb" / Number "207.2 g Pb" = Number "0.01548 mol Pb"

To find the number of moles of HCl that reacted, use the moles of Pb that reacted as well as the mole ratio of Pb and HCl. Write the mole ratio with HCl on top, which will cancel mol Pb and leave mol HCl.

#"0.01548 mol Pb"# x #"2 mol HCl"/"1 mol Pb"# = #"0.03096 mol HCl"#

Utilizing the molar mass of the HCl, convert the moles that reacted to mass.

#"0.03096 mol HCl"# x #"36.461 g HCl"/"1 mol HCl"# = #"1.129 g HCl"#

To answer: 3.208 g of Pb and 1.129 g of HCl completely react.

Please leave a comment if you have any questions.

Wyatt Atkins · Answer

undefined To determine the mass of HCl needed to react completely with 3.208 g of Pb, you need to use stoichiometry. First, write the balanced chemical equation:

Pb + 2HCl -> PbCl2 + H2

Then, calculate the molar mass of PbCl2:

Pb: 207.2 g/mol
Cl: 35.45 g/mol (x2 because there are two Cl atoms in PbCl2)

Molar mass of PbCl2 = 207.2 + (35.45 * 2) = 278.1 g/mol

Next, calculate the moles of Pb using its molar mass:

moles of Pb = mass of Pb / molar mass of Pb

moles of Pb = 3.208 g / 207.2 g/mol = 0.0155 moles

According to the balanced equation, 1 mole of Pb reacts with 2 moles of HCl. Therefore, the moles of HCl needed can be calculated:

moles of HCl = 2 * moles of Pb

moles of HCl = 2 * 0.0155 = 0.031 moles

Finally, calculate the mass of HCl using its molar mass:

mass of HCl = moles of HCl * molar mass of HCl

mass of HCl = 0.031 moles * 36.46 g/mol (molar mass of HCl)

mass of HCl ≈ 1.13 grams