Answer:
The no. of moles of CaCl₂ are needed = 3.1 mol.
Explanation:
- From the balanced reaction:
<em>2AgNO₃ + CaCl₂ → 2AgCl + Ca(NO₃)₂,</em>
It is clear that 2 mol of AgNO₃ react with 1 mol of CaCl₂ to produce 2 mol of AgCl and 1 mol of Ca(NO₃)₂.
<u><em>Using cross multiplication:</em></u>
2 mol of AgNO₃ need → 1 mol of CaCl₂ to react completely, from stichiometry.
6.2 mol of AgNO₃ need → ??? mol of CaCl₂ to react completely.
∴ The no. of moles of CaCl₂ are needed = (1 mol)(6.2 mol)/(2 mol) = 3.1 mol.
Mass of metal is 8.37 g, volume of water in graduated cylinder is 20 mL. After adding the metal, water level increases to 23.1 mL. The volume of metal is equal to the increase in water level.
The increase in water level can be calculated by taking difference of final and initial level of water.
Thus,

Density of metal is defined as mass per unit volume of metal. It can be calculated as follows:

This value corresponds to the density of aluminum.
Therefore, density is 2.7 g/mL and metal is aluminum.