The molar mass of caffeine is \(194.19 \mathrm{~g}\). Is the molecular formula of caffeine \(\mathrm{C}_{4} \mathrm{H}_{5} \mathrm{~N}_{2} \mathrm{O}\) or \(\mathrm{C}_{8} \mathrm{H}_{10} \mathrm{~N}_{4} \mathrm{O}_{2} ?\)

Short Answer

Expert verified
The molecular formula for caffeine is C8H10N4O2.

Step by step solution

01

Calculate the Molar Masses of the Formulas Given

First, calculate the molar mass of each of the suggested formulas by adding up the molar mass of each element in the formula, multiplied by the number of times it appears. Use the atomic masses for carbon (C), hydrogen (H), nitrogen (N), and oxygen (O) from the periodic table: \n\nFor C4H5N2O: Molar mass = 4*(12.01 g) + 5*(1.01 g) + 2*(14.01 g) + 1*(16.00 g) = 97.09 g \n\nFor C8H10N4O2 : Molar mass = 8*(12.01 g) + 10*(1.01 g) + 4*(14.01 g) + 2*(16.00 g) = 194.18 g
02

Compare with Given Molar Mass

Now, compare the calculated molar masses for both suggested formulas with the given molar mass for caffeine. Observe that the calculated molar mass for the formula C8H10N4O2 is nearly identical to the given molar mass, suggesting that is the correct formula.
03

Verify the integrity

Since only integer multiples are valid, and the resulting factor for C4H5N2O (2.00) is integer, we confirm that C8H10N4O2 is indeed the molecular formula of Caffeine.

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Most popular questions from this chapter

Calculate the number of \(\mathrm{C}, \mathrm{H},\) and \(\mathrm{O}\) atoms in \(1.50 \mathrm{~g}\) of glucose \(\left(\mathrm{C}_{6} \mathrm{H}_{12} \mathrm{O}_{6}\right)\), a sugar.

Nitrous oxide \(\left(\mathrm{N}_{2} \mathrm{O}\right)\) is also called "laughing gas." \(\mathrm{It}\) can be prepared by the thermal decomposition of ammonium nitrate \(\left(\mathrm{NH}_{4} \mathrm{NO}_{3}\right)\). The other product is \(\mathrm{H}_{2} \mathrm{O} .\) (a) Write a balanced equation for this reaction. (b) How many grams of \(\mathrm{N}_{2} \mathrm{O}\) are formed if 0.46 mole of \(\mathrm{NH}_{4} \mathrm{NO}_{3}\) is used in the reaction?

A mixture of \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\) and \(\mathrm{MgSO}_{4} \cdot 7 \mathrm{H}_{2} \mathrm{O}\) is heated until all the water is lost. If \(5.020 \mathrm{~g}\) of the mixture gives \(2.988 \mathrm{~g}\) of the anhydrous salts, what is the percent by mass of \(\mathrm{CuSO}_{4} \cdot 5 \mathrm{H}_{2} \mathrm{O}\) in the mixture?

Potash is any potassium mineral that is used for its potassium content. Most of the potash produced in the United States goes into fertilizer. The major sources of potash are potassium chloride \((\mathrm{KCl})\) and potassium sulfate \(\left(\mathrm{K}_{2} \mathrm{SO}_{4}\right)\). Potash production is often reported as the potassium oxide \(\left(\mathrm{K}_{2} \mathrm{O}\right)\) equivalent or the amount of \(\mathrm{K}_{2} \mathrm{O}\) that could be made from a given mineral. (a) If \(\mathrm{KCl}\) costs \(\$ 0.055\) per \(\mathrm{kg}\), for what price (dollar per \(\mathrm{kg}\) ) must \(\mathrm{K}_{2} \mathrm{SO}_{4}\) be sold in order to supply the same amount of potassium on a per dollar basis? (b) What mass (in \(\mathrm{kg}\) ) of \(\mathrm{K}_{2} \mathrm{O}\) contains the same number of moles of \(\mathrm{K}\) atoms as \(1.00 \mathrm{~kg}\) of \(\mathrm{KCl} ?\)

Which of the following has a greater mass: 2 atoms of lead or \(5.1 \times 10^{-23}\) mole of helium?

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