Answer:
See below.
Step-by-step explanation:
We call this conversion factor the molar ratio.
1. Start with the balanced equation
NiCO₃ + 2HCl ⟶ NiCl₂ + H₂O + CO₂
2. Note the coefficients of the substances
The equation tells you that 1 mol of NiCO₃ reacts with 2 mol of HCl·
Thus, the conversion factor is either (1 mol NiCO₃/2 mol HCl) or (2 mol HCl/1 mol NiCO₃).
You choose the one that gives the correct units for the answer.
For example, if the question was, "How many moles of HCl will react with x mol of NiCO₃," you would write
x mol NiCO₃ × (2 mol HCl/1 mol NiCO₃) ⟶ 2x mol HCl
Notice that putting "mol HCl" in the numerator and "mol NiCO₃" in the denominator cancels "mol NiCO₃" and gives you the desired units of "mol HCl" in the answer .