Question

Determine the molecular formulas of these compounds:

Answer 1

The molecular formulas of the empirical ones of P₂O₅ and CH₂O are P₄O₁₀ and C₇H₁₄O₇, respectively, knowing that their molar masses are 310 and 200.18 g/mol, respectively.  

1. Molecular formula of P₂O₅

We can calculate the molecular formula as follows:

$MF = n*EF$   (1)

Where:

• MF: is the molecular formula

• EF: is the empirical formula

• n: is an integer  

To calculate the integer n, we need to use the following equation:

$n = \frac{M}{M_{EF}}$   (2)

Where:

• M: is the molar mass of P₂O₅ =  310 g/mol

• $M_{EF}$: is the molar mass of the empirical formula

The molar mass of the empirical formula of P₂O₅  is given by:

$M_{EF} = 2A_{P} + 5A_{O}$

Where:

• $A_{P}$: is the atomic weight of phosphorus = 30.974 g/mol

• $A_{O}$: is the atomic weight of oxygen = 15.999 g/mol

So, the molar mass of the empirical formula of P₂O₅  is:

$M_{EF} = (2*30.974 + 5*15.999) g/mol = 141.943 g/mol$  

Now, we can find the integer n (eq 2).

$n = \frac{M}{M_{EF}} = \frac{310 \:g/mol}{141.943 \:g/mol} = 2$  

Finally, after multiplying the integer n by the number of atoms on the empirical formula of P₂O₅, we have (eq 1):

$MF = n*EF = 2 \times P_{2}O_{5} = P_{(2 \times 2)}O_{(5 \times 2)} = P_{4}O_{10}$

Therefore, the molecular mass of P₂O₅ is P₄O₁₀.

2. Molecular formula of CH₂O  

We know:

• M: molar mass of CH₂O = 200.18 g/mol

To calculate the integer n and so the molecular mass of the molecule, we need to calculate the molar mass of the empirical formula of CH₂O.

$M_{EF} = A_{C} + 2A_{H} + A_{O} = (12.011 + 2*1.008 + 15.999) g/mol = 30.026 \:g/mol$

 

Now, the integer n is equal to (eq 2):

$n = \frac{M}{M_{EF}} = \frac{200.18 g/mol}{30.026 g/mol} \approx 7$

Finally, the molecular formula of the molecule is (eq 1):

$MF = n*EF = 7 \times CH_{2}O = C_{(1 \times 7)}H_{(2 \times 7)}O_{(1 \times 7)} = C_{7}H_{14}O_{7}$                              

Therefore, the molecular formula of CH₂O is C₇H₁₄O₇.

Learn more about molecular formula here:

• brainly.com/question/1247523

• brainly.com/question/14327882

I hope it helps you!