#### Answer

32.1 g of potassium benzoate trihydrate.

#### Work Step by Step

1. Calculate the molar mass for $KC_7H_5O_2*3H_2O$:
39.1* 1 + 12.01* 7 + 1.008* 5 + 16* 2 + 3 * ( 1.008* 2 + 16.00* 1 ) = 214.26g/mol
2. Use the data and the molar mass as conversion factors:
** Notice: Each mole of potassium benzoate trihydrate yields 1 mol of potassium benzoate. So, we don't have to convert the number of moles.
$1.0 L (Solution) \times \frac{0.150 mol}{1 L (Solution)} \times \frac{214.26g}{1mol} = 32.1 g$