Question

Find the mass of 1.5 moles of water.

Answer 1

Hint: Water is a substance composed of hydrogen and oxygen. A molecule of water contains two units of hydrogen and one unit of oxygen. Mole of a substance indicates the amount of a substance used for making a known concentration of solution.

Complete step by step answer:
The substance used in this question is water. The mass of the substance is determined using the moles of substance given and the molar mass of the substance.
The molar mass of water is evaluated as follows:
\[\;{M_{{H_2}O}}\] = \[2{\text{ }} \times \] atomic mass of hydrogen + atomic mass of oxygen.
\[{M_{{H_2}O}} = {\text{ }}2 \times \left( {1.0078} \right) + 15.999 = 18.0146g\]
The mole of water is equal to the ratio of mass of water and the molar mass of water. The given number of moles of water = \[1.5moles\]
According to the mole equation,
\[mole = {\text{ }}\dfrac{{mass{\text{ }}of{\text{ }}water}}{{molar{\text{ }}mass{\text{ }}of{\text{ }}water}}{\text{ }}\]
Thus, \[mass{\text{ }}of{\text{ }}water = Molar{\text{ }}mass{\text{ }} \times {\text{ }}moles{\text{ }}of{\text{ }}water{\text{ }}\]
Substituting the values of molar mass and moles of water in the above formula gives
$\Rightarrow$ \[mass = 18.0146 \times 1.5\]
$\Rightarrow$ \[mass = 27.0219{\text{ }}g\]

Additional Information:
A mole of a substance is equal to the ratio of the mass of the substance and the molar mass of that substance. One mole of a substance contains \[6.023 \times {10^{23}}\] numbers of particles. The SI unit for mole of a substance is denoted as \[mole\] . Mole is equivalent to g/mL. Hence the mole of a substance in solution is related to the molarity of the solution.

Note:
Mole calculation is very important in determining the amount of product formed in a reaction. It gives the exact amount of reactant used for a reaction. If a substance is taken with weight equal to the molar mass of the substance, it is equal to \[1mole\] of the substance.