Chemistry: Gold has an atomic weight of 196.97 g/mol, and a density of 19.3 g/cm3. approximately how many atoms are in a spherical gold nanoparticle 10 nm in diameter?

Gold has an atomic weight of 196.97 g/mol, and a - id196972242187, hmskevinjacobo5471

isaicruz2018

02.01.2022

The number of atoms in spherical gold nano particle are $26.918\times 10^4$

Explanation:

To calculate the volume of sphere, we use the equation:

$V=\frac{4}{3}\pi r^3$

where,

r = radius of the sphere = $10nm=10^{-6}cm$ (Conversion factor: $1nm=10^{-7}cm$ )

Putting values in above equation, we get:

$V=\frac{4}{3}\times 3.14\times (10^{-6})^3\\\\V=4.19\times 10^{-18}cm^3$

To calculate mass of of the substance, we use the equation:

$\text{Density of substance}=\frac{\text{Mass of substance}}{\text{Volume of substance}}$

Volume of gold = $4.19\times 10^{-18}cm^3$

Density of gold = 19.3g/cm^3

Putting values in above equation, we get:

$19.3g/cm^3=\frac{\text{Mass of gold}}{4.19\times 10^{-18}}\\\\\text{Mass of gold}=8.0867\times 10^{-17}g$

To calculate the number of moles, we use the equation:

$\text{Number of moles}=\frac{\text{Given mass}}{\text{Molar mass}}$

Mass of gold = $8.8067\times 10^{-17}g$

Molar mass of gold = 196.97 g/mol

Putting values in above equation, we get:

$\text{Moles of gold}=\frac{8.8067\times 10^{-17}g}{196.97g/mol}=4.47\times 10^{-9}moles$

According to mole concept:

1 mole of an element contains $6.022\time 10^{23}$ number of atom

So, $4.47\times 10^{-19}$ moles of gold will contain = $4.47\times 10^{-19}\times 6.022\times 10^{23}=26.918\times 10^4$ number of atoms.

Hence, the number of atoms in spherical gold nano particle are $26.918\times 10^4$

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DerekMoncoal

07.03.2021

The correct answer is transfer pipette that had markings every 0.1 mL

Explanation:

Flask, beaker , pipette and graduated cylinder are the apparatus that are used in the lab to measure the volume of a chemical.

For an experiment, the measurement of chemical used must be precise and for that purpose, pipette is used.

All the other apparatus does not give precise measurements and hence cannot be used for measuring a chemical that has to be used in an experiment.

Hence, the correct answer is transfer pipette that had markings every 0.1 mL

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