Question

deduce the number of molecules in 126g water​

Answer 1

$\LARGE{ \underline{\underline{ \purple{ \bf{Required \: answer:}}}}}$

GiveN:

• Mass of water = 126 g

To FinD:

• No. of molecules in 126 g of Water (H2O)

Step-wise-Step Explanation:

Mass of H2O = 126 g

Molar mass of H2O = 2(1) + 16 = 18 g/mol

$\therefore$No. of moles = $\rm{\dfrac{Mass \: of \: substance}{Molar\: mass \:of \:substance}}$

By using the formula,

⇒ n = Mass / Molar mass

⇒ n = 126 g / 18 g/mol

⇒ n = 7 moles

$\therefore$No. of molecules = $\rm{No. \:of \:moles \times N_A}$

⇒ N = n × Na

⇒ N = 7 × 6.022 × 10²³ molecules

⇒ N = 42.154 × 10²³ molecules

⇒ N = 4.2154 × 10²⁴ molecules [Ans]