Answer:
The correct answer is: 2.8 ppm Ca²⁺ and 0.55 ppm Mg²⁺
Explanation:
ppm (by mass) is equal to: mass solute (mg)/mass solution(kg)
First, we use the solution density to calculate the mass of 100.0 L solution in kg:
mass solution= 100.0 L x 1.001 g/ml x 1000 ml/ 1L x 1kg/1000 g= 100.1 kg
Then, we divide the mass of each ion (in mg) into the mass solution to obtain the ppm:
mg Ca²⁺= 0.280 g x 1000 mg/1g= 280 mg
mg Mg²⁺= 0.0550 g x 1000 mg/1g= 55 mg
ppm Ca²⁺= 280 mg Ca²⁺/ 100.1 kg solution= 2.797 mg Ca²⁺/kg solution= 2.8 ppm
ppm Mg²⁺= 55 mg Mg²⁺/ 100.1 kg solution= 0.549 mg Mg²⁺/kg solution= 0.55 ppm
