Question

how many molecules of sf6 are in 25.0 g sf6? (1 mol sf6 = 146.06 g) (1 mol sf6 = 6.02 × 10²³ molecules) ? × 10^? molecules sf6 enter the coefficient in the green box and the exponent in the yellow box. coefficient (green) exponent (yellow)

Explanation:

Step1: Calculate the number of moles of \( SF_6 \)

Use the formula \( n=\frac{m}{M} \), where \( m = 25.0\ g \) (mass of \( SF_6 \)) and \( M=146.06\ g/mol \) (molar mass of \( SF_6 \)).
\( n=\frac{25.0\ g}{146.06\ g/mol}\approx0.171\ mol \)

Step2: Calculate the number of molecules of \( SF_6 \)

Use Avogadro's number \( N = n\times N_A \), where \( n = 0.171\ mol \) and \( N_A=6.02\times 10^{23}\ molecules/mol \)
\( N=0.171\ mol\times6.02\times 10^{23}\ molecules/mol\)
\( N=(0.171\times6.02)\times 10^{23}\)
\( 0.171\times6.02 = 1.03\) (approximate value)

Answer:

Coefficient (green): \( 1.03 \)
Exponent (yellow): \( 23 \)