Final answer:
To prepare a 0.400L solution of 0.155M Sr(OH)2, calculate the moles of Sr(OH)2 needed, convert this to grams, and dissolve the solid in enough water to make up the final volume of 0.400L.
Step-by-step explanation:
To prepare 0.400L of a 0.155M solution of Sr(OH)2 from solid Sr(OH)2, you need to calculate the amount of solute required. Using the molarity formula, M = moles/L, you can find the moles of Sr(OH)2 needed:
Moles of Sr(OH)2 = Molarity × Volume (in liters)
Moles of Sr(OH)2 = 0.155M × 0.400L
Next, convert the moles to grams using the molar mass of Sr(OH)2:
Mass of Sr(OH)2 (in grams) = Moles × Molar Mass of Sr(OH)2
After calculating the required mass, measure out that amount of solid Sr(OH)2 and dissolve it in enough water to make a final volume of 0.400L in a volumetric flask.
Ensure the solution is well mixed for homogeneity. This process will give you a 0.400L 0.155M Sr(OH)2 solution.