Question

Determine how many micrograms of phosphorus are in the following solutions:

1. 0.02M KH₂PO₄

2. 0.3M KH₂PO₄

3. 0.5M KH₂PO₄

4. 0.8M  KH2PO4

5. 1M  KH2PO4

6. 1.3M KH₂PO₄

Answer 1

1. 0.02M KH2PO4

0.02 moles of KH₂PO₄ in 1000 mL of solution.

Molar mass of KH₂PO₄ = 136.086 g/mol

molar mass of P = 30.97 g/mol

So, in 1 mole of P = 30.97 g of P

In 0.02 moles of P = (30.97 x 0.02) g of P = 0.619 g of P

Now, 1 g = 10⁶ microgram

0.619 g of P = 6.19 x 10⁵ microgram.

2.

0.3M KH2PO4

0.3 moles of KH₂PO₄ in 1000 mL of solution.

Molar mass of KH₂PO₄ = 136.086 g/mol

molar mass of P = 30.97 g/mol

So, in 1 mole of P = 30.97 g of P

In 0.3 moles of P = (30.97 x 0.3) g of P = 9.29 g of P

Now, 1 g = 10⁶ microgram

9.29 g of P = 9.29 x 10⁶ microgram.

3.

0.3M KH2PO4

0.5 moles of KH₂PO₄ in 1000 mL of solution.

Molar mass of KH₂PO₄ = 136.086 g/mol

molar mass of P = 30.97 g/mol

So, in 1 mole of P = 30.97 g of P

In 0.5 moles of P = (30.97 x 0.5) g of P = 15.49 g of P

Now, 1 g = 10⁶ microgram

15.49 g of P = 15.49 x 10⁶ microgram.

4.

0.8 M KH2PO4

0.8 moles of KH₂PO₄ in 1000 mL of solution.

Molar mass of KH₂PO₄ = 136.086 g/mol

molar mass of P = 30.97 g/mol

So, in 1 mole of P = 30.97 g of P

In 0.8 moles of P = (30.97 x 0.8) g of P = 24.78 g of P

Now, 1 g = 10⁶ microgram

24.78 g of P = 24.78 x 10⁶ microgram.

5.

1 M KH2PO4

1 moles of KH₂PO₄ in 1000 mL of solution.

Molar mass of KH₂PO₄ = 136.086 g/mol

molar mass of P = 30.97 g/mol

So, in 1 mole of P = 30.97 g of P

Now, 1 g = 10⁶ microgram

30.97 g of P = 30.97 x 10⁶ microgram.

6.

1.3M KH2PO4

1.3 moles of KH₂PO₄ in 1000 mL of solution.

Molar mass of KH₂PO₄ = 136.086 g/mol

molar mass of P = 30.97 g/mol

So, in 1 mole of P = 30.97 g of P

In 1.3 moles of P = (30.97 x 1.3) g of P = 40.26 g of P

Now, 1 g = 10⁶ microgram

40.26 g of P = 40.26 x 10⁶ microgram.