f the original solution contained 0.12 mol HCl , what amount of HCl , in moles, will remain when the reaction is complete? 1.4 g Zn reacted.

To determine how much HCl remains after the reaction with zinc (Zn), we first need to know the balanced chemical equation for the reaction between zinc and hydrochloric acid (HCl): \[ \text{Zn (s)} + 2 \text{HCl (aq)} \rightarrow \text{ZnCl}_2 (aq) + \text{H}_2 (g) \] From the balanced equation, we can see that 1 mole of Zn reacts with 2 moles of HCl. ### Step 1: Calculate moles of Zn First, we need to calculate the number of moles of zinc that reacted. The molar mass of zinc (Zn) is approximately 65.38 g/mol. \[ \text{Moles of Zn} = \frac{\text{mass of Zn}}{\text{molar mass of Zn}} = \frac{1.4 \, \text{g}}{65.38 \, \text{g/mol}} \approx 0.0214 \, \text{mol} \] ### Step 2: Calculate moles of HCl required According to the balanced equation, 1 mole of Zn reacts with 2 moles of HCl. Therefore, the moles of HCl required for the reaction with 0.0214 moles of Zn is: \[ \text{Moles of HCl required} = 2 \times \text{moles of Zn} = 2 \times 0.0214 \, \text{mol} \approx 0.0428 \, \text{mol} \] ### Step 3: Determine remaining moles of HCl Initially, there are 0.12 moles of HCl. After the reaction, the remaining moles of HCl can be calculated as follows: \[ \text{Remaining moles of HCl} = \text{Initial moles of HCl} - \text{Moles of HCl required} \] \[ \text{Remaining moles of HCl} = 0.12 \, \text{mol} - 0.0428 \, \text{mol} \approx 0.0772 \, \text{mol} \] ### Conclusion The amount of HCl that will remain when the reaction is complete is approximately **0.0772 moles**.