Question #c96db

1 Answer
Mar 2, 2015

!! LONG ANSWER !!

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

For C:25.305%12.011=1.9403

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

For C:1.904031.9403=1

For Cl:2.106891.9403=1.08581

The empirical formula will be (C1Cl1)x.

To determine the value of x and find the molecular formula, you must use the ideal gas law, PV=nRT, to find the moles of gas in your sample, which will then get you to the molar mass of the gas. So,

PV=nRTn=PVRT=1.10 atn10103L0.082atmLmolK291.0K

ngas=0.00046098 moles

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

Mm=0.00046098 moles0.04373 g=94.86 g/mol

x will be

(12.011+35.4527)x=94.86

x=94.8647.4637=1.99852

The molecular formula is C2Cl2 dichloroethyne (or dichloro acetylene).

Now for the Lewis structure. The total number of valence electrons will be 22 4 from each carbon atom and 7 from each chlorine atom. The Lewis structure will look like this

![http://www.gopixpic.com/1275/c2cl2-lewis-structure-165684060png/http:%7C%7Cimgdocstoccdncom%7Cthumb%7Corig%7C165684060*png/](useruploads.socratic.org)

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 180C.

![http://www.chemeddl.org/resources/models360/models.php