Use the equation given to determine the \"theoretical\" values of g M / moles H2

Question

Use the equation given to determine the "theoretical" values of g M / moles H2 (note that "M" is simply the metal, which is either La, Ba, Mn, or Pb). The equation is g metal / moles H2 = mass of metal / (moles H2/moles metal).

The unknowns are each one of the following metals - La, Ba, Mn, Pb. Calculate the theoretical values of g M/ moles H2 for each of these metals. In each case, the metal chloride product is identified to the right to help determine the ratio of moles M / moles H2 produced.

g / La moles H2 - ? (LaCi 3 is produced)

g / Ba moles H2 - ? (BaCi 2 is produced)

g / Mn moles H2 - ? (MnCI2 is produced)

g / Pb moles H2 - ? (PbCI 2 is produced)

Write the balanced chemical equation for the reaction between the metals given and HCl (for example, La + HCl ----> LaCl3 + H2....this equation needs to be balanced first). From the balanced chemical equation, you can determine the moles of H2/moles La. Remember that the number of moles is just the number of the coefficient in from of the molecule. For example, if you have 3H + 2O ---> 4H2O, there are 3 moles of H, 2 moles of O, and 4 moles of H2O in that equation. The mass of the metal (La) is just the atomic mass of La obtained from the periodic table.

Explanation / Answer

(1) 2 Li + 6 HCl ------------------> 2 LiCl3 + 3H2

moles metal / moles of H2 = 2/3

metal moles = 2

mass / molar mass = 2

mass / 7 = 2

mass = 14 g

mass of metal / moles of H2 = 14 / 3

Ba + 2 HCl ------------------> BaCl2 + H2

moles of metal / moles of H2 = 1 / 1

Ba mass / molar mass = 1

mass / 137 = 1

Ba mass = 137 g

mass of metal / moles of H2 = 137 g / 1

Mn + 2 HCl ------------------> MnCl2 + H2

moles of metal / moles of H2 = 1 / 1

moles of metal / moles of H2 = 1 / 1

Mn mass / molar mass = 1

mass / 55 = 1

Mn mass = 55 g

mass of metal / moles of H2 = 55 g / 1

Pb + 2 HCl ------------------> PbCl2 + H2

moles of metal / moles of H2 = 1 / 1

moles of metal / moles of H2 = 1 / 1

Pb mass / molar mass = 1

mass / 207 = 1

Pb mass = 207 g

mass of metal / moles of H2 = 207 g / 1

Note: i think you are given La instead of Li

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