FeCl3 + 3H2O → Fe(OH)3 + 3HCl Element Mass of an Atom (amu) Fe 56 Cl 35 H 1 O 16 Iron chloride and water react according to the equation shown. The table shows the atomic masses of the elements involved in the reaction. What is the total mass of the reactants?

1. 108 amu
2. 161 amu
3. 215 amu
4. 179 amu

1 answer

To calculate the total mass of the reactants in the reaction given by:

\[ \text{FeCl}_3 + 3\text{H}_2\text{O} \rightarrow \text{Fe(OH)}_3 + 3\text{HCl} \]

we need to find the molar masses of all the reactants, which are \( \text{FeCl}_3 \) and \( 3\text{H}_2\text{O} \).

  1. Calculate the mass of \( \text{FeCl}_3 \):

    • Iron (Fe): 1 atom × 56 amu = 56 amu
    • Chlorine (Cl): 3 atoms × 35 amu = 105 amu
    • Total mass of \( \text{FeCl}_3 \): \[ 56 \text{ amu} + 105 \text{ amu} = 161 \text{ amu} \]
  2. Calculate the mass of \( 3\text{H}_2\text{O} \):

    • Hydrogen (H): 2 atoms × 3 molecules = 6 atoms × 1 amu = 6 amu
    • Oxygen (O): 3 atoms × 16 amu = 48 amu
    • Total mass of \( 3\text{H}_2\text{O} \): \[ 6 \text{ amu} + 48 \text{ amu} = 54 \text{ amu} \]
  3. Calculate the total mass of the reactants:

    • Total mass of reactants = mass of \( \text{FeCl}_3 \) + mass of \( 3\text{H}_2\text{O} \): \[ 161 \text{ amu} + 54 \text{ amu} = 215 \text{ amu} \]

So, the total mass of the reactants is 215 amu.

The answer is 3. 215 amu.