Answer:
[tex]\boxed {\boxed {\sf 5.2 *10^{22} \ molecules \ NaCl}}[/tex]
Explanation:
1. Convert grams to moles
First, convert grams to moles using the molar mass. This can be found on the Periodic Table.
Sodium (Na) has an oxidation state of +1 and chlorine (Cl) has an oxidation state of -1, so they combine in a 1:1 ratio for a formula of NaCl. We can simply add their moles masses.
Use this as a ratio.
[tex]\frac {58.4397693 \ g \ NaCl}{ 1 \ mol \ NaCl}[/tex]
Multiply by the given number of grams.
[tex]5.0 \ g \ NaCl *\frac {58.4397693 \ g \ NaCl}{ 1 \ mol \ NaCl}[/tex]
Flip the fraction so the grams of sodium chloride cancel.
[tex]5.0 \ g \ NaCl *\frac {1 \ mol \ NaCl}{ 58.4397693 \ g \ NaCl}[/tex]
[tex]5.0 *\frac {1 \ mol \ NaCl}{ 58.4397693 }=\frac {5.0 \ mol \ NaCl} { 58.4397693 } = 0.0855581749 \ mol \ NaCl[/tex]
2. Convert moles to molecules
We must use Avogadro's Number. This tells us the amount of particles (molecules, atoms, etc.) in 1 mole of a substance. In this case, it is molecules of sodium chloride.
[tex]\frac{6.022*10^{23} \ molecules \ NaCl} {1 \ mol \ NaCl}[/tex]
Multiply by the number of moles we calculated.
[tex]0.0855581749 \ mol \ NaCl*\frac{6.022*10^{23} \ molecules \ NaCl} {1 \ mol \ NaCl}[/tex]
The moles of sodium chloride cancel.
[tex]0.0855581749 *\frac{6.022*10^{23} \ molecules \ NaCl}{1}=5.15231329*10^{22} \ molecules \ NaCl[/tex]
The original measurement of grams has 2 (2 and 0) significant figures, so our answer must have the same. For the number we calculated, that is the hundredth place. The 5 in the hundredth place tells us to round the 1 to a 2.
[tex]5.2 *10^{22} \ molecules \ NaCl[/tex]
