Myrcene is a naturally occurring compound found in the leaves of bay trees - VCE - SSCE Chemistry - Question 4 - 2009 - Paper 1

To calculate the amount of hydrogen gas in moles, we can use the Ideal Gas Law formula:

$n = \frac{PV}{RT}$

Where:

• P = pressure (105.0 kPa = 105000 Pa)
• V = volume (0.510 L = 510 mL)
• R = universal gas constant (8.31 J/(mol·K))
• T = temperature in Kelvin (20.0°C = 293 K)

Substituting in the values:

$n(H_2) = \frac{105000 \times 0.510}{8.31 \times 293} = 0.0220 \text{ moles}$

To calculate the mass of C10H22 produced, we first find the number of moles of C10H22. Given that the reaction yields one mole of C10H22 per mole of myrcene, we can determine the mass:

$m = n \times M$

Where M is the molar mass of C10H22 (142.28 g/mol). Since 0.0220 moles of hydrogen were used, it will also convert to 0.0220 moles of C10H22:

$m(C_{10}H_{22}) = 0.0220 \times 142.28 = 3.14 ext{ g}$

Myrcene (C10H16) has 3 double bonds. This can be deduced from the fact that when it reacts with hydrogen to become C10H22, each double bond reacts with one molecule of H2 to saturate the compound, indicating the presence of three C=C double bonds in each myrcene molecule.