Calcium phosphate was obtained from phosphorus weighing 3.10 g as a result of a series of successive reactions.

Calcium phosphate was obtained from phosphorus weighing 3.10 g as a result of a series of successive reactions. Write the equations of the corresponding chemical reactions and calculate the mass of the salt formed in this case.

To solve this problem, we write given: m (P) = 3.10 g
Find: m (Ca3 (PO4) 2) -?
Decision:
To get calcium phosphate from phosphorus, you need to write two reactions.
P + O2 = P2O5
Let’s arrange the coefficients.
4P + 5O2 = 2P2O5
Let’s calculate the mass of phosphorus (V) oxide, which is formed as a result of the reaction.
Calculate the molar masses of phosphorus and phosphorus (V) oxide
M (P) = 31 g / mol
M (P2O5) = 31 * 2 + 16 * 5 = 142 g / mol
We write 3.1 g above phosphorus, and 124 g below phosphorus.
Above phosphorus (V) oxide we write x g, and under – 284 g
Let’s compose and solve the proportion:
x = 3.1 * 284/124 = 7.1 g
Let’s write the second reaction equation:
P2O5 + 3CaO = Ca3 (PO4) 2
Calculate the molar mass of Ca3 (PO4) 2
M (Ca3 (PO4) 2) = 40 * 3 + (31 + 16 * 4) * 2 = 310 g / mol
Over the oxide of phosphorus (V) we write 7.1 g, and under – 142 g
Over Ca3 (PO4) 2 we write y g, and under Ca3 (PO4) 2 – 310 g
Let’s compose and solve the proportion:
y = 7.1 * 310/142 = 15.5 g
Answer: 15.5 g