I used the polynomial trendline because it was the best fitting. In calculations I used temp in K!!!

Anyway, I think that I understood why they obtained a different value. So, as you saw, I obtained 2.7 micromoles while they obtained 59 micromoles because they used in the equation, not the thiophene vapor pressure at 10.8C but the standard conditions of T and P. So, in this case, the final value will be 59. But I am not sure that it is correct like this.

On the other side, if we dived he volume of thiophene (0.00134 L) to 22.4 L, we’ll get 59 micromoles, as well.

What actually happen?

We have a flow of thiophene in H2. This flow is 25.7 ml/min and contain 5.2 vol% of thiophene.

What do you think? Is OK to use STP conditions to calculate the number of mole of thiophene in this flow?