thomas has 235 grams of k₂s in the chemistry lab. how many atoms of potassium (k) are in 235 grams of the…

Explanation:

Step1: Calculate molar mass of $K_2S$

The molar mass of $K$ is approximately $39.1\ g/mol$ and of $S$ is approximately $32.1\ g/mol$. So molar mass of $K_2S$ is $2\times39.1 + 32.1=78.2+32.1 = 110.3\ g/mol$.

Step2: Calculate moles of $K_2S$

Number of moles of $K_2S$, $n=\frac{m}{M}$, where $m = 235\ g$ and $M = 110.3\ g/mol$. So $n=\frac{235}{110.3}\approx2.13\ mol$.

Step3: Determine moles of $K$

In one - mole of $K_2S$, there are 2 moles of $K$. So moles of $K$ in $2.13\ mol$ of $K_2S$ is $2\times2.13 = 4.26\ mol$.

Step4: Calculate number of $K$ atoms

Using Avogadro's number $N_A=6.022\times 10^{23}\ atoms/mol$, the number of $K$ atoms $N = n\times N_A$. So $N=4.26\times6.022\times 10^{23}\approx 2.57\times 10^{24}$ atoms.

Answer:

C. $2.57\times 10^{24}$