Question

compare (a) the numer of atoms and (b) the number of grams present in 1.00 mole of helium and 1.00 mole of argon

Answer 1

Answer:

For a: The number of atoms of both the gases remains the same.

For b: The number of grams of 1 mole of argon is more than 1 mole of helium by 35.95 grams.

Explanation:

• For a:

To calculate the number of atoms, we use mole concept.

According to mole concept:

1 mole of an element contains $6.022\times 10^{23}$ number of atoms.  

We are given two gases of same number of moles.

Therefore, 1 mole of helium gas will contain $1\times 6.022\times 10^{23}=6.022\times 10^{23}$ number of atoms.

and, 1 mole of argon gas will contain $1\times 6.022\times 10^{23}=6.022\times 10^{23}$ number of atoms.

Hence, number of atoms of both the given gases remains the same.

• For 2:

As, the molar mass of both the gases are different, so their masses in 1 mole will be different.

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

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

• Calculating the mass of Helium in 1 mole:

Molar mass of helium = 4 g/mol

Putting the values in above equation, we get:  

$1mol=\frac{\text{Given mass}}{4g/mol}=4grams$

• Calculating the mass of Argon in 1 mole:

Molar mass of Argon = 39.95 g/mol

Putting the values in above equation, we get:  

$1mol=\frac{\text{Given mass}}{39.95g/mol}=39.954grams$

Calculating the difference of masses of both the gases = (39.95 - 4)g = 35.95g

Therefore, the mass of argon is more than mass of helium by 35.95 grams.