Conservation in Chemical Reactions Quick Check
Science 8 Q1 / Matter Interactions
Use the equation and the table to answer the question.
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 point)
Responses
108 amu
161 amu
179 amu
215 amu
To find the total mass of the reactants, we need to add up the atomic masses of each element in the reactants FeCl3 and H2O.
FeCl3:
Fe (Atomic mass = 56 amu) + Cl3 (Atomic mass of one Cl atom = 35 amu) = 56 amu + 3 * 35 amu = 56 amu + 105 amu = 161 amu
H2O:
H2 (Atomic mass of one H atom = 1 amu) + O (Atomic mass = 16 amu) = 2 * 1 amu + 16 amu = 2 amu + 16 amu = 18 amu
Total mass of the reactants = Mass of FeCl3 + Mass of H2O = 161 amu + 18 amu = 179 amu
Therefore, the correct answer is 179 amu.
To find the total mass of the reactants, we need to sum the atomic masses of each element involved, multiplied by their respective coefficients.
For FeCl3:
Mass of Fe = 56 amu
Mass of Cl = 35 amu (x3 as there are 3 Cl atoms)
Total mass of FeCl3 = 56 amu + (35 amu * 3) = 56 amu + 105 amu = 161 amu
For H2O:
Mass of H = 1 amu (x2 as there are 2 H atoms)
Mass of O = 16 amu
Total mass of H2O = (1 amu * 2) + 16 amu = 2 amu + 16 amu = 18 amu
Adding the total masses of FeCl3 and H2O:
Total mass of reactants = Total mass of FeCl3 + Total mass of H2O = 161 amu + 18 amu = 179 amu
Therefore, the total mass of the reactants is 179 amu.
The correct answer is: 179 amu.