Question

What mass of iodine would react with 48 grams of magnesium to make magnesium iodide? Mg + I2 -> MgI2

Answer 1

1) Chemical equation:

Mg + I2 ---> Mg I2

2) molar ratios

1 mol Mg : 1 mol I2 : 1 mol Mg I2

3) Calculate the number of moles of Mg in 48 grams

Atomic mass of Mg: 24.3 g/mol

number of moles = mass in grams / atomic mass = 48 g / 24.3 g/mol = 1.975 mol Mg

4) Use a proportion with the molar ratios

1 mol I2 / 1 mol Mg = x / 1.975 mol Mg =>

=> x = 1 mol I2 * 1.975 mol Mg / 1 mol Mg = 1.975 mol I2

5) Convert 1.975 mol I2 to grams

molar mass of I2 = 2 * 126.9 g/mol = 253.8 g/mol

mass = number of moles * molar mass = 1.975 mol * 253.8 g/mol = 501.255 g

Answer: 501 grams