How would you solve this problem?...
magnesium metal reacts rapidly in hot water. Predict the mass of pericipitate that will form if a 2.0g strip of magnesium reacts completely with water.
*Use the 5-step method*
*Answer: 4.8g*
I don't know what the five step method is, and I suspect few do know.
Here is how to do it.
Balance the equation.
Determine the moles of Mg from the mass of Mg.
Determine the moles of MgO from the balanced equation.
Convert the moles of MgO to mass.
To solve this problem using the 5-step method, here's a step-by-step explanation:
Step 1: Balance the equation
The chemical equation for the reaction between magnesium and water is:
Mg + H2O → MgO + H2
Step 2: Determine the moles of Mg from the mass of Mg
To find the moles of magnesium, you need to use the molar mass of magnesium (24.31 g/mol). Use the formula:
moles = mass / molar mass
Given that the mass of magnesium is 2.0g, you can calculate the moles of Mg:
moles of Mg = 2.0g / 24.31 g/mol
Step 3: Determine the moles of MgO from the balanced equation
From the balanced equation, you can see that the stoichiometric ratio between Mg and MgO is 1:1. This means that one mole of Mg will produce one mole of MgO.
Since you have already calculated the moles of Mg in the previous step, you can directly say that the moles of MgO will be equal to the moles of Mg.
Step 4: Convert the moles of MgO to mass
To find the mass of the precipitate (MgO), you need to multiply the moles of MgO by its molar mass (40.31 g/mol).
mass of MgO = moles of MgO * molar mass of MgO
mass of MgO = moles of Mg * molar mass of MgO
Substituting the values:
mass of MgO = (2.0g / 24.31 g/mol) * 40.31 g/mol
Step 5: Calculate the final answer
Perform the calculation to find the mass of the precipitate:
mass of MgO = (2.0g / 24.31 g/mol) * 40.31 g/mol
mass of MgO ≈ 3.29g
Therefore, the predicted mass of the precipitate (MgO) that will form if a 2.0g strip of magnesium reacts completely with water is approximately 3.29g.