Balance the following Equation:

___Zn + ___HCl - -> ___ZnCl2 + ___H2

50g of zinc are reacted with 50g of hydrogen chloride. Calculate the amount of excess reactant.

A - 4.2g

B - 5.1g

C - 1.4g

D - 2.3g

The amount of excess is 5.16 grams. Option B is correct

Explanation:

Step 1: Data given

Mass of Zinc (Zn) = 50.0 grams

Mass of Hydrogen chloride (HCl) = 50.0 grams

atomic mass Zn = 65.38 g/mol

Molar mass HCl = 36.46 g/mol

Step 2: The balanced equation

Zn + 2HCl → ZnCl2 + H2

step 3: Calculate moles

Moles = mass / molar mass

Moles Zn = 50.0 grams / 65.38 g/mol

Moles Zn = 0.764 moles

Moles HCl = 50.0 grams / 36.46 g/mol

Moles HCl = 1.37 moles

Step 4: Calculate limiting reactant

For 1 mol n we need 2 moles HCl to produce 1 mol ZnCl2 and 1 mol H2

HCl is the limiting reactant. It will completely be consumed (1.37 moles)

Zn is in excess. There will react 1.37/2 = 0.685 moles

There will remain 0.764 - 0.685 = 0.079 moles

Step 5: Calculate the remaining mass of zinc

Mass = moles * molar mass

Mass Zinc = 0.079 moles * 65.38 g/mol

Mass Zinc = 5.16 grams

The amount of excess is 5.16 grams. Option B is correct