Question

How many formula units make up 11.4 g of magnesium chloride (MgCl2)?

Answer 1

To determine the number of formula units in 11.4 grams of MgCl2, we convert grams to moles and then use the molar ratio to calculate the number of formula units. There are 0.2398 formula units of MgCl2 in 11.4 grams.

Step-by-step explanation:

Magnesium chloride (MgCl2) is an ionic compound composed of one magnesium ion (Mg2+) and two chloride ions (Cl-). To determine the number of formula units in 11.4 g of MgCl2, we need to convert grams to moles and then use the molar ratio to calculate the number of formula units.

First, calculate the moles of MgCl2 in 11.4 g using the molar mass of MgCl2, which is 95.21 g/mol:

11.4 g MgCl2 x (1 mol MgCl2/95.21 g MgCl2) = 0.1199 mol MgCl2

Since the atomic ratio of Mg to Cl in MgCl2 is 1:2, the number of formula units of MgCl2 is twice the number of moles:

0.1199 mol MgCl2 x 2 = 0.2398 formula units

Answer 2

A mol has several meanings: 1 mol of an atom, molecule or formula unit contains 6.022 x 10^23 atoms or the Avogadro's Number. Therefore, a formula unit is equal to a mole. Calculation of the formula units of magnesium chloride as follows;

11.4 g (1 mol/ 95.21 g) = 0.12 mol or formula unit