posted by Sydney .
How mush CaCl2, in grams, is needed to make 2.0 L of a 3.5M solution?
g CaCl2 = (2.0L) *( 3.5 mol Cl-/1L) * (1mol CaCl2/ 2mol Cl-)
*( 110.98 g CaCl2/ 1 mol CaCl2) = 5.549 g CaCl2
i don't think i did any of this right
You made two errors. The rest is ok.
You want grams CaCl2 and not Cl so omit Cl.
That's mols needed = M x L = 2.00L x 3.5M = 7.00 mols.
Then grams = mols x molar mass = 7.00 x 110.98 = about 777 g.
How you obtained 5.55 grams I don't know. YOu must have punched the wrong numbers into the calculator.