Propenes can be produced by the cracking of some hydrocarbons obtained from crude oil - Edexcel - GCSE Chemistry - Question 5 - 2019 - Paper 1

To calculate the mass of products formed, we first determine the moles of decane:

1. Find the molar mass of decane, C_{10}H_{22}:

   • Molar mass = 10(12) + 22(1) = 142g/mol.

2. Moles of decane in 25g: $Moles = \frac{mass}{molar \ mass} = \frac{25}{142} \approx 0.176 \text{ mol}$

3. Using the balanced equation, 1 mole of decane produces 1 + 1 = 2 moles of products. Therefore, total moles of products produced = 0.176 * 2 = 0.352 mol.

4. Molar mass of the products (butene and the other molecule) is approximately the same as decane, around 142g/mol. Thus, total mass of products is: $Total \ mass = moles \times molar \ mass = 0.352 \times 142 = 50.144g \approx 50g$.

In Figure 9, you should represent the double bond between the two carbon atoms (C=C) by showing:

• 4 electrons represented as dots or crosses between these carbons to indicate the double bond. This can be illustrated as follows:
  • C : •• : C (using dots for electrons)
  • Or C : xx : C (using crosses for electrons) Thus, showing that there are two pairs of electrons shared in the double bond.

Another product of the incomplete combustion of ethene is carbon monoxide (CO). This occurs when there is a limited supply of oxygen, leading to the incomplete oxidation of the hydrocarbon.