Question

Saline is 9 g of salt per 1 kg of water. What ppm is this?

Answer 1

ppm is used to give the concentration of a solution

ppm stands for parts per million. In this question we are calculating weight of salt in 1 kg of solution

1000 mg is equivalent to 1 g

then 1000 g is equivalent to 1 kg

therefore 10⁶ mg is equivalent to 1 kg

there's 9 g of salt in 1 kg of water

the total weight of the solution is 1 kg + 0.009 kg = 1.009 kg

so we need to find out how many mg of salt is in 1 kg of saline

1.009 kg of saline contains - 9000 mg

then 1 kg of saline contains - 9000 mg / 1.009 kg = 8920 mg/kg

mg/kg is called ppm

therefore concentration of saline is 8920 ppm

Answer 2

Density of water is 1 kg/L

There is 9 g of salt per 1 kg of water, on converting mass of water into its volume, there will be 9 g of salt per litre of water

1 ppm is equal to mg per litre

Since, 1 mg = 0.001 g

Thus, 1 ppm is equal to 0.001 g per litre

1 g/ l will be
`(1)/(0.001)ppm`

Therefore, 9 g/l =
`9 * (1)/(0.001)ppm = 9000 ppm`

Hence, concentration of saline in water is 9000 ppm.