2. Answer the following questions about a sample of calcium phosphate:

a. What is the molecular weight of Ca3(PO4)2?

b. How many moles of Ca3(PO4)2are in 1350g?

c. How many molecules of Ca3(PO4)2 are there in 1350g?

d. How many phosphorus atoms are there in 1350g of Ca3(PO4)2?

e. How many moles of calcium are there in 1350 g of Ca3(PO4)2?

f. What is the mass of 2.1 x 1025molecules of Ca3(PO4)2?

a) 310.18 g/mol

b) 4.352 moles Ca3(PO4)2

c) 2.6 * 10^24 molecules

d) 5.24 * 10^24 P atoms

e)13.056 moles Ca

f)10825.3 grams

Explanation:

Step 1: Data given

Atomic mass of Ca = 40.08 g/mol

Atomic mass of P = 30.97 g/mol

Atomic mass of O = 16.0 g/mol

Step 2: Calculate molecular weight of Ca3(PO4)2

Molecular weight of Ca3(PO4)2 = 3*atomic mass of Ca + 2* atomic mass of P and 8* atomic mass of O

Molecular weight of Ca3(PO4)2 = 3*40.08 + 2*30.97 + 8*16.0  = 310.18 g/mol

Step 3: Calculate moles of Ca3(PO4)2 in 1350 grams

Moles Ca3(PO4)2 = mass Ca3(PO4)2 /molar mass

Moles Ca3(PO4)2 = 1350 grams / 310.18 g/mol

Moles Ca3(PO4)2 = 4.352 moles

Step 4: Calculate molecules in 1350 grams

Molecules = moles * number of Avogadro

Molecules = 4.352 moles * 6.02 * 10^23

Molecules = 2.6 *10^24 molecules

Step 5: Calculate moles Phosphorus

For 1 mol Ca3(PO4)2 we need 2 moles P

For 4.352 moles Ca3(PO4)2 we have 2*4.352 = 8.704 moles

Step 6: Calculate P atoms

Atoms P = 8.704 moles * 6.02*10^23

Atoms P = 5.24 * 10^24 P atoms

Step 7: Calculate moles Calcium in 1350 grams

For 1 mol Ca3(PO4)2 we have 3 moles Ca

For 4.352 moles we have 3*4.352 = 13.056 moles Ca

Step 8: Calculate mass of 2.1 * 10^25 molecules of Ca3(PO4)2

Moles Ca3(PO4)2 = 2.1 * 10^25 / 6.02 * 10^23

Moles Ca3(PO4)2 = 34.9 moles

Mass Ca3(PO4)2 = 34.9 moles * 310.18 g/mol

Mass Ca3(PO4)2 = 10825.3 grams

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