Question

The source of bitterness in dark chocolate is the compound theobromine, an alkaloid present in cocoa beans. In a sample of dark chocolate there are 6.45 × 10 20 molecules of theobromine present. How many milligrams of theobromine are present in the sample? The molecular formula for theobromine is C 7 H 8 N 4 O 2 .

Answer 1

Answer: 193 mg of theobromine are present in the sample.

Step-by-step explanation:

According to avogadro's law, 1 mole of every substance occupies 22.4 L at STP and contains avogadro's number of particles.

To calculate the moles, we use the equation:

`\text{Number of moles}=\frac{\text{Given molecules}}{\text {Avogadros number}}=(6.45* 10^(20))/(6.023* 10^(23))=1.07* 10^(-3)moles`

1 mole of theobromine
`(C_7H_8N_4O_2)` weigh = 180 g

`1.07* 10^(-3)moles` of theobromine
`(C_7H_8N_4O_2)` weigh =
`(180)/(1)* 1.07* 10^(-3)=0.193g=193mg` (1g=1000mg)

193 mg of theobromine are present in the sample.