Question

How would you make 100ml of an aqueous solution with a 0.25 M concentration of a compound that has a molecular weight of 200 daltons?

a. Dissolve 0.25 moles of the compound in 100ml of water
b. Add 50g of the compound to 100ml of water
c. Combine 0.25 moles of the compound with 100ml of a solvent
d. Mix 25g of the compound with 100ml of a solvent

Answer 1

To prepare a 0.25 M solution, dissolve 5 grams of the compound with a molecular weight of 200 daltons in 100ml of water. option a is correct.

Step-by-step explanation:

To make 100ml of an aqueous solution with a 0.25 M concentration of a compound that has a molecular weight of 200 daltons, you first need to calculate the mass of the compound required. The number of moles needed for 100ml (0.1 L) can be calculated by multiplying the volume in liters by the molarity (moles/Liter), which gives us 0.025 moles (0.1 L × 0.25 moles/Liter).

Next, to find the mass of the compound, we multiply the number of moles by the molecular weight (200 daltons per mole), resulting in 5 grams (0.025 moles × 200 g/mole). Therefore, the correct option is to mix 5 grams of the compound with 100 ml of solvent (water, in this case), ensuring that the solvent volume is measured after adding the compound to accurately make a 0.25 M solution.