Question

determine the mass in grams of 2.91 moles of licl

Explanation:

Step1: Find molar mass of LiCl

Li (lithium) has molar mass ~6.94 g/mol, Cl (chlorine) ~35.45 g/mol. Molar mass of LiCl = 6.94 + 35.45 = 42.39 g/mol.

Step2: Use moles to mass formula

Mass (g) = moles × molar mass. Moles = 2.91, molar mass = 42.39 g/mol.
So, Mass = 2.91 mol × $\frac{42.39\ \text{g}}{1\ \text{mol}}$

Step3: Calculate the mass

2.91 × 42.39 = 123.3549 g (approx 123 g, but let's check the given numbers. Wait, the given options have 42.39, 2.91. So 2.91 × 42.39 = 123.3549, which is ~123. But let's do the calculation properly. 2.91 42.39: 242.39=84.78, 0.942.39=38.151, 0.0142.39=0.4239; sum: 84.78+38.151=122.931+0.4239=123.3549 g.

Answer:

The mass is approximately 123 grams (using 2.91 mol × $\frac{42.39\ \text{g}}{1\ \text{mol}}$ = 123.35 g, which rounds to 123 g).