What is the molecular formular?

Answer 1

A molecular formula shows how many of what kind of atoms are in a molecule of a compound. Water, having two atoms of hydrogen and one atom of oxygen has the molecular formula H2O. Sulfuric acid, with two hydrogen atoms, one sulfur atom, and four oxygen atoms, is written H2SO4.

Answer 2

A molecule is an electrically neutral group of at least two atoms held together by covalent chemical bonds. Molecules are distinguished from ions by their electrical charge. However, in quantum physics, organic chemistry, and biochemistry, the term molecule is often used less strictly and applied to polyatomic ions.

In the kinetic theory of gases, the term molecule is often used for any gaseous particle regardless of its composition. According to this definition noble gas atoms are considered molecules despite the fact that they are composed of a single non-bonded atom.

A molecule may consist of atoms of a single chemical element, as with oxygen (O2), or of different elements, as with water (H2O). Atoms and complexes connected by non-covalent bonds such as hydrogen bonds or ionic bonds are generally not considered single molecules.

Molecules as components of matter are common in organic substances (and therefore biochemistry). They also make up most of the oceans and atmosphere. A large number of familiar solid substances, however, including most of the minerals that make up the crust, mantle, and core of the Earth itself, contain many chemical bonds, but are not made of identifiable molecules. No typical molecule can be defined for ionic crystals (salts) and covalent crystals (network solids), although these are often composed of repeating unit cells that extend either in a plane (such as in graphene) or three-dimensionally (such as in diamond or sodium chloride). The theme of repeated unit-cellular-structure also holds for most condensed phases with metallic bonding. In glasses (solids that exist in a vitreous disordered state), atoms may also be held together by chemical bonds without any definable molecule, but also without any of the regularity of repeating units that characterises crystals.

Answer 3

Question:

The hydrocarbon used in a common lighter was analysed by burning.

A 5.249g sample of the gas is burnt and the resulting water vapour was collected in a cold trap. This produced 8.198g of water.

Another 3.121g sample of the compound was released into a sealed container and this occupied a volume of 1.289L at 23.5°C and 102.5kPa.

What is the molecular formula of this hydrocarbon?

THIS IS THE QUESTION I WAS GIVEN I DONT KNOW HOW TO FIGURE IT OUT!

Answer: C4H10Let M be the molar mass of the compound X (in g/mol)

1. From burning the hydrocarbon:

   5.249 gX produces 8.198 gH2O = 8.198(gH2O)/18.02(g/molH2O) = 0.4550(molH2O) = 0.4550*2(H atoms per molH2O) = 0.910 mol H atoms in 5.249 gX

2. From the given gas volume and the general Ideal Gas Law:

   the number of moles n = p.V / R.T

   it follows that:

   3.121 gX / M g/molX = n (molX) = p.V / R.T =

   [102.5*1000 (Pa)]*[1.289/1000 (m3)] / [8.314 (J/mol.K)]*[23.5+273.15 (K)] = 132.13(J) / 2466.3(J/mol) = 0.05357 mol X in 3.121 g X

3. So from (2) it follows that M = 3.121(gX) / 0.05357(molX) = 58.26 g/mol X
4. and from (1) and (2) it follows that 5.249 gX = 5.249(gX) / 58.26(g/molX) = 0.0901 mol X was burnt.
5. From (4) and (1) it follows that 0.0901 molX contained 0.910 mol H atoms
6. This means that the H atom ratio per mole X is about 10.1 H/mol
7. Now some probable hydrocarbon molar masses can be used to compare with:

   C4H10 M=58 g/mol (butane)

   C5H10 M=70 g/mol (pentene)

   From this only C4H10 looks to be the most reasonable choice.

   To prove that this is correct, burn it: it should give about 8.2 g of water like in the experiment of burning.

8. C4H10 (+ O2) --> 5 H2O + (CO2), thus

   5.249 gX is in moles:

   5.249/58.26 mol X = 0.0901 mol X

   On burning 5 times as much H2O is produced: this is 5*0.0901= 0.4505 mol H2O and 0.4505(molH2O)*18.02(g/molH2O)= 8.118 g H2O; [this is quite close to the given experimental value of 8.198 g H2O (difference 0.08 g = 1%)]

The molecular formula of this sustance is C4H10 with molar mass 58.08 g/mol, which is the most nearest to the experimental molar mass found 58.26 g/mol.

Answer 4

A chemical formula that shows the number and kinds of atoms in a molecule.

Answer 5

The type and number of atoms in a molecule.

Answer 6

A formula that gives the elements in a compound and the ratio of atoms

Answer 7

Depends on the composition of the molecule. A sugar molecule doesn't look the same as a gasoline molecule.

Answer 8

Formular is a Danish word that is translated to formula in the English language. Formulas are a specific game plan used in order to solve a specific problem.