If one 5 mL dose of Milk of Magnesia contains 400 mg of magnesium
hydroxide, calculate the concentration of magnesium hydroxide in mol/L.
400mg/l>>.4/molmassMg(OH)2 /.05=.14M about, check it.
To calculate the concentration of magnesium hydroxide in mol/L, we first need to convert milligrams (mg) to grams (g).
Given:
- 1 mL = 1 cm^3
- The density of water is 1 g/cm^3
- The density of Milk of Magnesia is approximately 1.46 g/mL
First, calculate the mass of magnesium hydroxide in one 5 mL dose:
Mass (in g) = Volume (in mL) × Density (in g/mL)
Mass (in g) = 5 mL × 1.46 g/mL
Next, convert the mass from mg to g:
Mass (in g) = 5 mL × 1.46 g/mL = 7.3 g
Now we can calculate the number of moles of magnesium hydroxide using the molar mass of Mg(OH)2.
Molar mass of Mg(OH)2 = (Molar mass of Mg) + 2 × (Molar mass of O) + 2 × (Molar mass of H)
Molar mass of Mg = 24.31 g/mol
Molar mass of O = 16.00 g/mol
Molar mass of H = 1.01 g/mol
Molar mass of Mg(OH)2 = 24.31 g/mol + 2 × 16.00 g/mol + 2 × 1.01 g/mol
Molar mass of Mg(OH)2 = 58.33 g/mol
Now, calculate the moles of magnesium hydroxide:
Moles = Mass (in g) / Molar mass (in g/mol)
Moles = 7.3 g / 58.33 g/mol
Finally, calculate the concentration in mol/L (Molarity):
Concentration (mol/L) = Moles / Volume (in L)
Volume (in L) = 5 mL / 1000 mL/L = 0.005 L (convert mL to L)
Concentration (mol/L) = (7.3 g / 58.33 g/mol) / 0.005 L
Now, solve for the concentration:
Concentration (mol/L) = 2.49 mol/L (rounded to two decimal places)
Therefore, the concentration of magnesium hydroxide in Milk of Magnesia is approximately 2.49 mol/L.