Over 80 000 vehicles per day pass the site and the traffic is frequently congested. The surrounding area is described as forming a street canyon. The temperature at the site had reached 25 °C by 08:00, when the ethane concentration was recorded as 7.09 ppbv. This is equivalent to 1.78 × 1011 molecules cm–3. At the same time, the concentration of ethene (C2H4, another product of combustion of petrol) was 7.54 × 1010 molecules cm–3 .
The hydroxyl radical, HO•, reacts with both ethene and ethane. For the concentrations and temperature given, calculate the ratio between the rate of the reaction of ethene and the rate of the reaction with ethane. Explain why the reaction rate per molecule is faster for ethene than it is for ethane.
Please help me.
Any ideas? I'm really struggling
To calculate the ratio between the rate of the reaction of ethene and the rate of the reaction with ethane, we need to consider the reaction rate constants and the concentrations of ethene and ethane.
Reaction rate is determined by the rate constant multiplied by the concentration of the reactants. In this case, the reactants are ethene and ethane, and the reaction involves the hydroxyl radical (HO•).
Let's denote the rate constant for the reaction of HO• with ethene as k1, and the rate constant for the reaction of HO• with ethane as k2.
The ratio between the rates of the two reactions can be represented as:
Rate of reaction with ethene / Rate of reaction with ethane = (k1 * [ethene]) / (k2 * [ethane])
To calculate this ratio, we need to know the rate constants and concentrations of ethene and ethane.
Unfortunately, the given information does not include the rate constants for the reactions of HO• with ethene and ethane. Without these values, we cannot determine the ratio between the reaction rates.
However, we can still explain why the reaction rate per molecule is faster for ethene than it is for ethane, based on the given information.
The reactivity of a molecule towards a reaction is influenced by several factors, including molecular structure and bond strength.
Ethene (C2H4) has a double bond between the carbon atoms, which is relatively weak compared to the single bonds in ethane (C2H6). This double bond makes ethene more reactive towards the hydroxyl radical.
The strength of the C=C bond in ethene makes it easier for the hydroxyl radical to break this bond, leading to a faster reaction rate. On the other hand, the single bonds in ethane are stronger and require more energy to break, resulting in a slower reaction rate.
Therefore, the reaction rate per molecule is faster for ethene than it is for ethane due to the molecular structure and bond strength differences between the two compounds.