Answer to Question #292709 in Chemistry for angel

Question

• what is the mass in grams of 1.204 x 10²³ molecules of H2O?

• how many formula units are there in 0.175 g of LiF

Answer 1

Solution:

(1):

One mole of any substance contains 6.022×10²³ particles.

Therefore,

Moles of H₂O = (1.204×10²³ molecules) × (1 mol / 6.022×10²³ molecules) = 0.1999 mol = 0.2 mol

The molar mass of H₂O is 18.0153 g/mol

Therefore,

Mass of H₂O = (0.2 mol H₂O) × (18.0153 g H₂O / 1 mol H₂O) = 3.603 g H₂O = 3.6 g H₂O

Answer (1): 3.6 grams of H₂O

(2):

The molar mass of LiF is 25.94 g/mol

Therefore,

Moles of LiF = (0.175 g LiF) × (1 mol LiF / 25.94 g LiF) = 0.00675 mol LiF

One mole of any substance contains 6.022×10²³ particles.

Therefore,

Formula units of LiF = (0.00675 mol) × (6.022×10²³ formula units / 1 mol) = 4.065×10²¹ formula units

Answer (2): 4.065×10²¹ formula units LiF