Question

3) The molar mass of a new prescription drug is 287.34 g/mol. If the manufacturer produces 537 moles of

Answer 1

Answer:  " 145,000 g " .

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Explanation:

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To solve:  Let's use a technique known as "dimensional analysis"

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$\frac{287.34 g}{mol}$ * ( 537 mol)  = ? g ;

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Note:  "g" stands for "grams" ;

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The units of "mol" ["mole(s)"] on the "left-hand side of the equation"

                               →  "cancel out" ;  {since: "mol/mol" = 1 "} ;

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And we have:

(287.34 * 537) g ;

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Using a calculator, we do the multiplication to get:

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  154301.58 g ;  We round this to 3 (three) significant figures;

since:  (287.34 * 537) g ;  the limiting number with the "least number of significant figure" is "537" ; which has 3 (three) significant figures;

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As such:

We have 154301.58 g ;

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We round this to 145,000 g ; since:

"154" are the first 3 (three) significant figures in our value:

 " 154301.58" ;  and the next significant figure, "3" ; is less than "5" ;

If the next significant figure were "0, 1, 2, 3, or 4" ; we  would round down to: 145,000 g; such as in our case.  If the next significant figure were "5, 6, 7, 8, or 9" , we would round up to: 146,000 g .

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The correct answer is:  " 145,000 g ."