Calculation of Molar Mass of Alkene

Given:
- Volume of alkene = 10 ml
- Volume of CO2 produced = 40 ml

Assumptions:
- Complete combustion of alkene
- All CO2 produced is collected and measured accurately
- Temperature and pressure are constant during the combustion

Steps to calculate molar mass:
1. Write the balanced chemical equation for the combustion of alkene:

CxHy + (x + (y/4))O2 → xCO2 + (y/2)H2O

2. From the equation, we can see that 1 mole of alkene produces x moles of CO2. Therefore, we need to find the number of moles of CO2 produced from the given volume:

Moles of CO2 = Volume of CO2 / Molar volume of gas at STP
= 40 ml / 22.4 L/mol (molar volume of gas at STP)
= 0.00179 mol

3. Since the combustion is complete, all the carbon atoms from alkene are converted into CO2. Therefore, the number of moles of CO2 produced is equal to the number of moles of carbon in alkene:

Moles of carbon in alkene = Moles of CO2 = 0.00179 mol

4. We can now calculate the molecular formula of alkene using the number of moles of carbon and hydrogen. Let's assume the alkene has the formula CnH2n. Then,

Moles of carbon in alkene = n
Moles of hydrogen in alkene = 2n

Therefore, n + 2n/4 = 0.00179 mol
4n + 2n = 0.00716 mol
n = 0.00143 mol

So, the molecular formula of alkene is C2H4.

5. Finally, we can calculate the molar mass of alkene using its molecular formula:

Molar mass of alkene = (2 x 12.01 g/mol) + (4 x 1.01 g/mol)
= 28.05 g/mol

Therefore, the molar mass of the given alkene is 28.05 g/mol.