# Question c96db

Mar 2, 2015

Let's start by determining the gas' molecular formula. This is done by determining the mole ratio that exists between carbon and chlorine in the compound.

Start by dividing the percentage each element has by its molar mass

$\text{For C": "25.305%"/"12.011" = "1.9403}$

$\text{For Cl:" "74.695%"/"35.4527" = "2.10689}$

DIvide each of these numbers by the smallest one to get the mole ratio between carbon and chlorine

$\text{For C": "1.90403"/"1.9403} = 1$

$\text{For Cl": "2.10689"/"1.9403" = "1.0858" ~= 1}$

The empirical formula will be ${\left({C}_{1} C {l}_{1}\right)}_{x}$.

To determine the value of $x$ and find the molecular formula, you must use the ideal gas law, $P V = n R T$, to find the moles of gas in your sample, which will then get you to the molar mass of the gas. So,

$P V = n R T \implies n = \frac{P V}{R T} = \left(\text{1.10 atn" * 10*10^(-3)"L")/(0.082("atm" * "L")/("mol" * "K") * 291.0"K}\right)$

n_("gas") = "0.00046098 moles"

DIvide the mass of the sample by the number of moles to get the molar mass

${M}_{m} = \text{0.00046098 moles"/"0.04373 g" = "94.86 g/mol}$

$x$ will be

("12.011 + 35.4527)*x = 94.86#

$x = \frac{94.86}{47.4637} = \text{1.9985} \cong 2$

The molecular formula is ${C}_{2} C {l}_{2}$ $\to$ dichloroethyne (or dichloro acetylene).

Now for the Lewis structure. The total number of valence electrons will be 22 $\to$ 4 from each carbon atom and 7 from each chlorine atom. The Lewis structure will look like this All the atoms have a full octet, and all the 22 valence electrons are accounted for.

According to VSEPR Theory, the molecular geometry will be linear, each carbon atom having both the steric number, and the coordination number equal to 2. i.e each carbon atom is only bonded to two other atoms and has no lone pairs. Bond angles will be ${180}^{\circ} \text{C}$. 