Question

to determine the concentration of a solution, you need to know how many moles of an ion, molecule, or compound there are in that solution. however, in the lab, you can often only measure substances by their mass in grams. convert 7.868e+1 grams of nacl to moles of nacl atoms. moles

Explanation:

Step1: Calculate the molar mass of NaCl

The molar mass of Na ($M_{Na}=22.99\ g/mol$) and Cl ($M_{Cl}=35.45\ g/mol$). The molar mass of NaCl, $M = M_{Na}+M_{Cl}=22.99 + 35.45=58.44\ g/mol$

Step2: Use the formula $n=\frac{m}{M}$

Given $m = 7.868\times10^{1}\ g$ (i.e., $m = 78.68\ g$) and $M = 58.44\ g/mol$. Then $n=\frac{78.68}{58.44}$
$n\approx1.346\ mol$

Answer:

$1.346$