How many grams of ca(no3)2 are needed to make 25.0 g of a 15.0% ca(no3)2(aq)?

3.75 g.

Explanation:

mass percent is the ratio of the mass of the solute to the mass of the solution multiplied by 100.

mass % = (mass of solute/mass of solution) x 100.

mass of calcium nitrite = ??? g,

mass of the solution = 25.0 g.

∴ mass % = (mass of solute/mass of solution) x 100

∴ mass of solute (calcium nitrite) = (mass %)(mass of solution)/100 = (15.0 %)(25.0 g)/100 = 3.75 g.

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