The molar mass of Na2CrO4 is 162.00 g/mol. To calculate the number of moles in 74.3 grams, we divide the mass by the molar mass:

$$moles \space Na_2CrO_4 = 74.3 \space g / 162.00 \space g/mol$$

$$moles \space Na_2CrO_4= 0.458 \space mol$$

Therefore, there are 0.458 moles of Na2CrO4 in 74.3 grams of the compound.