Answer to Question #101435 in Chemistry for Jessica

Question

You have 4,100 g of magnesium.How many grams of water must be used to have all of the magnesium react 2 form Mg(OH)2 in the following equation. Mg+2H2O=Mg(OH)2+H2

Answer 1

According to the equation of reaction, one part of magnesium Mg react with two parts of water H2O, hence we need twice as much water when comparing in moles.

First, compute the amount of magnesium. Molar mass of magnesium is 24.3 g/mole, hence

q_magnesium=(4100 g)/(24.3 g/mole)≈168.7 mole

Second, compute the amount of water from the equation of reaction:

q_water=2∙q_magnesium=2∙168.7 mole=337.4 mole

Then, compute the mass of water. Molar mass of water is 16+2=18 g/mole, hence

m_water=337.4 mole∙18 g/mole=6703.2 g

Answer:

The amount of water that must be used is 6,703.2 grams.