what is the mass of LiF is needed to produce 2.5 L of a .30 M solution

To calculate the mass of LiF needed to produce a solution, we can use the equation:

Molarity = moles of solute / volume of solution

First, let's rearrange the equation to solve for moles of solute:

Moles of solute = Molarity × volume of solution

Given:
Molarity = 0.30 M (moles per liter)
Volume of solution = 2.5 L

So, the moles of solute required can be calculated as follows:

Moles of solute = 0.30 mol/L × 2.5 L = 0.75 mol

To calculate the mass of LiF, we need to know the molar mass of LiF, which consists of lithium (Li) with a molar mass of 6.94 g/mol and fluorine (F) with a molar mass of 18.99 g/mol.

Molar mass of LiF = (molar mass of Li) + (molar mass of F)
= 6.94 g/mol + 18.99 g/mol
= 25.93 g/mol

Finally, we can calculate the mass of LiF required:

Mass of LiF = moles of solute × molar mass of LiF
= 0.75 mol × 25.93 g/mol
= 19.45 g

Therefore, the mass of LiF needed to produce 2.5 L of a 0.30 M solution is approximately 19.45 grams.