Question

Use the method of dimensional analysis to solve this problem: What is the mass, in milligrams, of 7.62 micromoles of caffeine?

Answer 1

Answer:

a2+b2=c2

Explanation:

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Answer 2

Given: 7.62 micromoles of caffeine is present

To find: Mass in milligrams of caffeine

Solution: The molecular formula of caffeine is C8H10N4O2 .

Number of moles of caffeine

= 7.62 micromoles

$= 7.62 \times {10}^{ - 6} moles$

(since 1 mole = 1000000 micromoles)

Molar mass of caffeine= 194 g/mol

Let the mass of caffeine be m.

We know that:

Moles = Mass / Molar mass

$= > 7.62 \times {10}^{ - 6} mol= \frac{m}{194 \: g \: {mol}^{ - 1} }$

$= > m = 7.62 \times {10}^{ - 6} \: mol \times 194 g \: {mol}^{ - 1}$

$= > m = 1478.28 \times {10}^{ - 6} g$

$= > m = 1478.28 \times {10}^{ - 3} mg$

(since 1 g = 1000 mg)

Therefore, the mass of 7.62 micromoles of caffeine is $1478.28 \times {10}^{ - 3} mg$.