Question

1. what sample contains more atoms: 1 mole of nacl or 1 mole of cacl₂?

1. which has more mass: 1 mole of carbon atoms or 1 mole of silicon atoms?

1. calculate the molar mass of ammonia (nh₃). show your work.

1. calculate the molar mass of hydrogen peroxide (h₂o₂). show your work.

1. which has more mass: 1 mole of ammonia (nh₃) or 1 mole of hydrogen peroxide molecules (h₂o₂)?

1. what has more atoms: 1 mole of ammonia (nh₃) or 1 mole of hydrogen peroxide molecules (h₂o₂)?

Explanation:

Step1: Count atoms in 1 mol NaCl

1 mole of $\text{NaCl}$ has $1$ mol $\text{Na}^+$ and $1$ mol $\text{Cl}^-$, so total atoms: $1+1=2$ mol

Step2: Count atoms in 1 mol CaCl₂

1 mole of $\text{CaCl}_2$ has $1$ mol $\text{Ca}^{2+}$ and $2$ mol $\text{Cl}^-$, so total atoms: $1+2=3$ mol

Step3: Compare molar masses (C vs Si)

Molar mass of $\text{C} = 12.01\ \text{g/mol}$, molar mass of $\text{Si} = 28.09\ \text{g/mol}$

Step4: Calculate molar mass of NH₃

Molar mass of $\text{N}=14.01\ \text{g/mol}$, $\text{H}=1.008\ \text{g/mol}$.
$\text{Molar mass of NH}_3 = 14.01 + 3\times1.008$
$\text{Molar mass of NH}_3 = 14.01 + 3.024 = 17.034\ \text{g/mol}$

Step5: Calculate molar mass of H₂O₂

$\text{Molar mass of H}_2\text{O}_2 = 2\times1.008 + 2\times16.00$
$\text{Molar mass of H}_2\text{O}_2 = 2.016 + 32.00 = 34.016\ \text{g/mol}$

Step6: Compare mass of NH₃ vs H₂O₂

1 mole of a substance has mass equal to its molar mass. $34.016 > 17.034$

Step7: Count atoms in NH₃ and H₂O₂

1 mole of $\text{NH}_3$ has $1+3=4$ mol atoms; 1 mole of $\text{H}_2\text{O}_2$ has $2+2=4$ mol atoms

Answer:

1. 1 mole of $\text{CaCl}_2$
2. 1 mole of silicon atoms
3. $17.03\ \text{g/mol}$ (rounded to two decimal places)
4. $34.02\ \text{g/mol}$ (rounded to two decimal places)
5. 1 mole of hydrogen peroxide ($\text{H}_2\text{O}_2$) molecules
6. They contain the same number of atoms