Question

How many grams of phosphorus are in 500.0 grams of calcium phosphate?

a. 310.2 grams
b. 49.92 grams
c. 130.1 grams
d. 99.89 grams?

Answer 1

To determine the amount of phosphorus in 500.0 grams of calcium phosphate, we calculate the molar mass of calcium phosphate and then find the proportion of phosphorus using the molar mass. The calculation leads to the answer of 99.89 grams of phosphorus. So the correct option is d.

Step-by-step explanation:

To find out how many grams of phosphorus are in 500.0 grams of calcium phosphate, we first need to calculate the molar mass of calcium phosphate (Ca3(PO4)2). The molar mass can be found by adding the mass of each element within the compound:

• 3Ca: (3 atoms) (40.078 amu/atom) = 120.234 amu
• 2P: (2 atoms) (30.973761 amu/atom) = 61.947522 amu
• 8O: (8 atoms) (15.9994 amu/atom) = 127.9952 amu

Adding these together, we get the formula mass of Ca3(PO4)2:
120.234 amu + 61.947522 amu + 127.9952 amu = 310.177 amu (rounded to 310.177 grams/mol for practical use).

Next, to find the portion of the mass that comes from phosphorus, we use the ratio of the mass of phosphorus to the molar mass of calcium phosphate:

(61.947522 g P / 310.177 g Ca3(PO4)2) x 500.0 g = 100 g P

The correct answer is:

• (d) 99.89 grams

Answer 2

Option D is correct; 99.89 grams

Step-by-step explanation:

Calcium phosphate is also known as tricalcium phosphate. The Chemical formula for the compound is Ca3(PO4)2.

The molar mass can be calculated as: 40 × 3 + (31×2) + (16×4)2.

= 120 + 62 + 128.

Molar mass of calcium phosphate= 310 g/mol.

Molar mass of phosphorus is 31 u

From the Chemical formula of calcium phosphate, we can see that we have 2 moles of phosphorus atoms. Therefore, we will have molar mass of phosphorus multiply by 2.

Hence,mass of phosphorus;

===> (31 × 2/ 310 )× 500 gram.

= 62/310× 500 gram.

= 100 grams.

QUICK NOTE: THERE IS SLIGHT DIFFERENCE IN 99.89 AND 100 GRAMS. THIS IS BECAUSE I ONLY USED THE NEAREST SIGNIFICANT VALUE (TO THE LEFT) AFTER THE DECIMAL POINT. FOR EXAMPLE; THE MASS NUMBER OF CALCIUM PHOSPHATE IS 310.177 g/mol and MASS NUMBER OF PHOSPHORUS IS 30.973762 u.