Question 4.12: Using Mass Percent Composition as a Conversion Factor The U....
Using Mass Percent Composition as a Conversion Factor
The U.S. Food and Drug Administration (FDA) recommends that a person consume less than 2.4 g of sodium per day. What mass of sodium chloride (in grams) can you consume and still be within the FDA guidelines? Sodium chloride is 39% sodium by mass.
SORT You are given a mass of sodium and the mass percent of sodium in sodium chloride. You are asked to find the mass of NaCl that contains the given mass of sodium.
GIVEN: 2.4 g Na
FIND: g NaCl
STRATEGIZE Convert between mass of a constituent element and mass of a compound by using mass percent composition as a conversion factor
CONCEPTUAL PLAN
RELATIONSHIPS USED
39 g Na: 100 g NaCl
SOLVE Follow the conceptual plan to solve the problem.
2.4 \cancel{g \ Na}\times \frac{100 \ g \ Nacl}{39 \ \cancel{g \ Na}}=6.2 \ gNacl
You can consume 6.2 g NaCl and still be within the FDA guidelines.
CHECK The units of the answer are correct. The magnitude seems reasonable because it is larger than the given amount of sodium, as expected, because sodium is only one of the elements in NaCl.
