Question

An alka-seltzer tablet contains 324 mg of aspirin (c9h8o4), 1904 mg of nahco3 and, 1000. mg of citric acid (h3c6h5o7). (the last two compounds react with each other to provide the "fizz," bubbles of co2, when the tablet is put into water.) if you take three tablets, how many molecules of aspirin are you consuming?

Answer 1

Answer:

Molecules of aspirin we are consuming is $3.2679\times 10^{21}$.

Explanation:

Mass of an aspirin in 1 alka-seltzer tablet = 324 mg = 0.324 g

Molar mass of an aspirin, $C_9H_8O_4$ = 180 g/mol

Moles of an aspirin in one tablet = $\frac{0.324 g}{180 g/mol}=0.0018 mol$

Number of molecules in 0.0018 moles of an aspirin:

$=0.0018 mol\times 6.022\times 10^{23} mol^{-1}$

$=1.0839\times 10^{21} molecules$

Number of molecules in of aspirin in 1 tablet:$1.0839\times 10^{21} molecules$

Number of molecules in of aspirin in 3 tablet:

$=3\times 1.0839\times 10^{21} molecules$

$=3.2679\times 10^{21} molecules$

Answer 2

Each alka-seltzer tablet contains 324 mg of aspirin. Three alka-seltzer tablet contains (3 x 324)mg= 972 mg of aspirin= 0.972 g of aspirin.

Molecular formula of aspirin is C₉H₈O₄. Molar mass of aspirin is (9 x 12)+(8 x 1)+(4 x 16) g/ mol= 180 g/mol.

180 g of aspirin contains 1 mole of aspirin molecules i.e, 6.023 X 10²³ number of aspirin molecules.  So, three alka-seltzer tablet that is 0.972 g of aspirin contains (0.972 X 6.023 X 10²³)/180 =3.25 X 10²¹ number of aspirin molecules.