Question

How many moles of water can be produced from the reaction of $\mathbf{28}\,\mathbf{g of }{{\mathbf{C}}_{\mathbf{3}}}{{\mathbf{H}}_{\mathbf{3}}}$?

Answer 1

Hint: The mole is the unit of measurement for amount of substance in the international system of units. It is defined as exactly $6.022\times {{10}^{23}}$ particles, which may be atoms, molecules, ions or electrons. To obtain the number of moles, divide the mass of the compound by the molar mass of the compound expressed is grams.

Complete step by step answer:
In general if you know the mass of a substance and the number of molecules, you can calculate the molecular weight (Mwt).
$\dfrac{\text{mass}}{\text{moles}}=\text{Mwt}\text{.}$
Rearrange the equation algebraically to get moles from Mwt and mass or mass from Mt and moles.
According to the given equation we have hydrocarbons ${{\text{C}}_{3}}{{\text{H}}_{8}}$ that is propane with mass of $28\,\text{g}$.
Combustion of a hydrocarbon gives water.
${{\text{C}}_{3}}{{\text{H}}_{8}}(g)\to 3\text{C}{{\text{O}}_{2}}(g)+4{{\text{H}}_{2}}\text{O(}l\text{)}$
Above chemical equation shows that $1\ \text{mole}$ of propane gives $3\ \text{moles}$ of carbon dioxide and moles of water.
Moles of propane $=\dfrac{\text{mass}}{\text{molecular weight}}=\dfrac{28.0\text{g}}{44.1\ \text{g/mol}}=\mathbf{0}\mathbf{.635}\ \mathbf{mol}$
According to the stoichionetric of the reaction, the water that is produced from the reaction has \[4\] numbers of molecules.
Therefore moles of water that an be produced
\[=0.635\times 4=\mathbf{2}\mathbf{.54}\ \mathbf{mol}\]
Hence $2.54$ mol of water can be produced from the reaction of $28$ g of ${{\text{C}}_{3}}{{\text{H}}_{8}}.$
One mole of water contains $6.02214076\times {{10}^{23}}$ molecules, whose total mass is about $18.015$ grams and the mean mass of one molecule of water is about $18.015$ Daltons.

Additional information:
The mole may also be used to measure the amount of atoms, ions, electrons, or other entities. The concentration of a solution is commonly expressed by its morality, defined as the amount of dissolved substance in mole per unit volume of solution, for which the unit typically used in moles per litre.
The term gram-molecule (gmol) was formerly used for mole of molecules and gram atom for mole of atoms. The history of the mole is intertwined with that of molecular mass atomic mass unit, and the Avogadro number. The Avogadro constant ${{\text{N}}_{\text{A}}}$ is related to other physical constants and properties.
(1) It relates molar gas constant and the Bolteman constant ${{\text{K}}_{\text{B}}}.$
$\text{R}={{\text{K}}_{\text{B}}}{{\text{N}}_{\text{A}}}.$
(2) It relates the faraday constant \[f\] and the elementary charge e.
$\text{F}=\text{e}{{\text{N}}_{\text{A}}}$
(3) It relates the molar mass constant, ${{\text{M}}_{\text{u}}}$ and atomic mass unit ${{\text{m}}_{\text{u}}}$.
${{\text{M}}_{\text{u}}}={{\text{m}}_{\text{u}}}{{\text{N}}_{\text{A}}}$
The Avogadro constant also relates the molar volume of a substance to the average volume nominally occupied by one of its particles, when both are expressed in the same units of volume.

Note: In a solid the constituent particles are fixed and bound in a lattice identity. Thus the solid is composed of a certain number of moles of such particles. In other cases, such as diamond, the entire crystal is essentially a single molecule; the mole is still used to express the number of atoms bound together, rather than a count of multiple molecules. The official mole is based on an outdated continuum concept of matter. The mole is not a true metric unit, rather it is a parametric unit, and the amount of substance is parametric base quantity. The Avogadro constant also relates the molar volume of a substance to the average volume nominally occupied by one of its particles, when both are expressed in the same units of volume. The mass of one mole of any substance is N times the average mass of one of its constituent particles.