Question

bellwork: mass to mole conversion
copy the question and answer the following in your notebook. show your work.

1. how many moles are in 254 g of ca₃(po₄)₂?
2. find the mole of 138 g mgn₃.
3. find the mole of 90 g c₄h₈o₂.

Explanation:

Step1: Calculate molar mass of \(Ca_3(PO_4)_2\)

Atomic masses: \(Ca = 40\space g/mol\), \(P = 31\space g/mol\), \(O = 16\space g/mol\)
\(Molar\space mass=3\times40 + 2\times(31 + 4\times16)=310\space g/mol\)

Step2: Calculate moles of \(Ca_3(PO_4)_2\)

\(n=\frac{m}{M}=\frac{254\space g}{310\space g/mol}\approx0.82\space mol\)

Step3: Calculate molar mass of \(MgN_3\)

Atomic masses: \(Mg = 24\space g/mol\), \(N = 14\space g/mol\)
\(Molar\space mass = 24+3\times14=66\space g/mol\)

Step4: Calculate moles of \(MgN_3\)

\(n=\frac{m}{M}=\frac{138\space g}{66\space g/mol}\approx2.09\space mol\)

Step5: Calculate molar mass of \(C_4H_8O_2\)

Atomic masses: \(C = 12\space g/mol\), \(H = 1\space g/mol\), \(O = 16\space g/mol\)
\(Molar\space mass=4\times12 + 8\times1+2\times16=88\space g/mol\)

Step6: Calculate moles of \(C_4H_8O_2\)

\(n=\frac{m}{M}=\frac{90\space g}{88\space g/mol}\approx1.02\space mol\)

Answer:

1. Approximately \(0.82\space mol\)
2. Approximately \(2.09\space mol\)
3. Approximately \(1.02\space mol\)