Question

How many molecules of HCI are in 4.91 L of HCI acid at 25°C if the density equals 1.096 g/ml

Answer 1

To determine the number of HCl molecules in 4.91 L of HCl acid at 25°C, we can use the following steps:

1. Calculate the mass of the HCl acid in 4.91 L using its density.
2. Convert the mass of HCl acid to the number of moles using its molar mass.
3. Use Avogadro's number to convert the number of moles of HCl to the number of HCl molecules.
4. Calculate the mass of the HCl acid in 4.91 L using its density:

`\qquad\sf {Density = (mass)/(volume)}`

`\qquad\sf{mass = density * volume}`

`\qquad\sf{mass = 1.096 \: g/mL * 4.91\: L = 5.38\: kg}`

Convert the mass of HCl acid to the number of moles using its molar mass. The molar mass of HCl is 36.46 g/mol.

`\sf{moles = (mass)/( molar\: mass) = (5.38\: kg)/(36.46\: g/mol) = 147.6\: mol}`

Use Avogadro's number to convert the number of moles of HCl to the number of HCl molecules. Avogadro's number is
`6.02 * 10^23` molecules/mol.

`\sf number\: of\: HCl\: molecules = moles * Avogadro's\: number`

`\begin{aligned}\sf number\: of\: HCl\: molecules& =\sf 147.6 \: mol * 6.02 * 10^23\: molecules/mol \\& =\sf 8.88 * 10^25\: molecules\end{aligned}`

Therefore, there are
`8.88 * 10^25` HCl molecules in 4.91 L of HCl acid at 25°C, assuming the density of the acid is 1.096 g/mL.

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