Question

Deduce the number of molecules of the following compounds in the given quantities. 8.8 g water​

Answer 1

Answer:

Formula to be used:

No of molecules = No of Moles × Avogadro Number of molecules

Given Mass: 8.8 g

Molar Mass of Water = 18 g

Hence Number of moles of water is:

$\implies n = \dfrac{8.8}{18} = \bf{0.48}$

Hence the number of moles of water present in 8.8 g of water is 0.48 moles.

Now we know that, 1 mole contains Avogadro number of molecules. Hence 0.48 moles will contain:

⇒ Number of molecules = 0.48 × Nₐ

⇒ Number of molecules = 0.48 × 6.023 × 10²³

⇒ Number of molecules = 2.89 × 10²³ molecules

Hence, the number of molecules present in 8.8 g of water is 2.89 × 10²³.

Answer 2

Information provided with us:

• Water is 8.8 g (H2O)

What we have to calculate:

• We have to calculate the number of molecules that water contains.

Let's start:

$\red\bigstar \: \sf{\underline {\underline{Finding \: out \: molar \: mass \: of \: water:- }}}$

We know that,

• Atomic weight of hydrogen is 1
• Atomic weight of oxygen is 16

So,

• Molar mass of water = 1 × 2 + 16
• Molar mass of water = 2 + 16
• Molar mass of water = 18

$\red\bigstar \: \sf{\underline {\underline{Finding \: out \: number \: of \: moles:- }}}$

• So as to calculate the number of moles of any substance we have to divide mass of the given solution with the molar mass of it.

$\boxed{ \bf{No. \: of \: moles \: = \: \dfrac{Total \: mass}{Molar \: mass} }}$

As we have,

• Quantity of water is 8.8g
• Molar mass of water is 18g

Let's do now!!

• Substituting the values:-

$: \longmapsto \: \sf{No. \: of \: moles \: = \: \dfrac{8.8}{18} }$

$: \longmapsto \: \sf{No. \: of \: moles \: = \: \dfrac{88}{18 \times 10} }$

$: \longmapsto \: \sf{No. \: of \: moles \: = \: \dfrac{ \cancel{88}}{ \cancel{18} \times 10} }$

$: \longmapsto \: \sf{No. \: of \: moles \: = \: \dfrac{44}{9 \times 10}}$

$: \longmapsto \: \sf{No. \: of \: moles \: = \: \dfrac{44}{90}}$

$: \longmapsto \: \sf{No. \: of \: moles \: = \: \cancel \dfrac{44}{90}}$

$: \longmapsto \: \boxed{\sf{No. \: of \: moles \: = \: 0.48}}$

$\red\bigstar \: \sf{\underline {\underline{Using \: avogadro's \: number:- }}}$

• Meanwhile Avogadro's number we can define it as amount of molecules present in 12g of C-12 isotope. (6.023 × 10²³ atoms)
• Avogadro's number is a number of elementary untis it states that number of atoms , or molecules present in one mole of substance.
• Mainly it is denoted by $\bf{{N_{A}}}$

Given:

• No. of moles is 0.48
• One mole contains = 6.023 × 10²³ molecules

To Find:

• 0.48 moles contains = ?

Let's start:

$: \longrightarrow \sf{Amount \: of \: molecules (i.e., number \: of \: molecules )\: = \:0.48 \times 6.023 \times 10 {}^{23} }$

$: \longrightarrow \sf{Amount \: of \: molecules (i.e., number \: of \: molecules )\: = \: \dfrac{48}{100} \times \dfrac{6023}{1000} \times 10 {}^{23} }$

$: \longrightarrow \sf{Amount \: of \: molecules (i.e., number \: of \: molecules )\: = \: \dfrac{ \cancel{48}}{ \cancel{100}} \times \dfrac{6023}{1000} \times 10 {}^{23} }$

• On simply multiplying now we gets because if we starts cancelling terms it would be too complicated.

$: \longrightarrow \red{\boxed{\sf{Amount \: of \: molecules (i.e., number \: of \: molecules )\: = \: 2.89 \times 10 {}^{23} }}}$

More Information:

• Molecular formula is a type of chemical formula which gives out the actual number of atoms of the elements present in one molecule of a compound.
• The relative atomic mass of an element is the number of times one atom of the element is heavier than 1/12 times of the mass of an atom of carbon-12.
• The molecular mass of a substance is expressed in grams is called gram molecular mass or molar mass.
• The molar volume of a gas we can even define as the volume occupied by one mole of a gas at S.T.P.