Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in grams) of the salt required to achieve 10 ppm of iron in 100 kg of wheat is .

Atomic weight: Fe = 55.85; S = 32.00; O

Question

Ferrous sulphate heptahydrate is used to fortify foods with iron. The amount (in grams) of the salt required to achieve 10 ppm of iron in 100 kg of wheat is .

Atomic weight: Fe = 55.85; S = 32.00; O = 16.00

Canvas Classes · Accepted Answer

Strategy:
 PPM (parts per million) by mass is equivalent to mg of solute per kg of solvent. For ferrous sulphate heptahydrate, calculate the moles of iron needed and find the corresponding mass of the entire salt.

Step 1: Determine mass of Iron () needed
Required concentration = 10 ppm = 10 mg  per 1 kg of wheat.
Total wheat = 100 kg.

Step 2: Calculate mass of  salt
The molar mass of  is .

Since there is 1 atom of  per formula unit, moles of salt required = 0.017905 mol.
- Molar mass of .

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