ocr a level chemistry question help

hi please can someone talk me through how to answer this? thank you!

(b) The second step in the manufacture of sulfuric acid is the conversion of SO2 into sulfur trioxide, SO3, using Equilibrium 1.
2SO2(g) + O2(g) 2SO3(g)      ∆H = −197 kJ mol−1 Equilibrium 1 An industrial chemist carries out some research into Equilibrium 1.
• The chemist fills a 10.2 dm3 container with SO2(g) at RTP, and then adds 12.0g of O2(g).
• The chemist adds the vanadium(V) oxide catalyst, and heats the mixture. The mixture is allowed to reach equilibrium at a pressure of 2.50atm and a temperature of 1000K.
• A sample of the equilibrium mixture is analysed, and found to contain 0.350 mol of SO3.

(ii) Determine the value of Kp for Equilibrium 1 at 1000K.
Show all your working.
Give your answer to 3 significant figures.

1. find the equilibrium moles of each reactant and product using the fact that 0.350 of SO3 is at equilibrium
2. convert these to partial pressures using molar fractions and the 2.5 atm in the question
3. sub into Kp expression
Hope that helps

thank you for your reply! but this is going to sound so stupid, how to I work out the moles of the reactant from 0.350? would i work out the initioal moles by using the 12.0g of oxygen? thank you

hey if you don't mind me asking, which paper is this question from?

It is from one of the papers that OCR have not yet made public.

could you please send it to me?

hi please can someone talk me through how to answer this? thank you!

(b) The second step in the manufacture of sulfuric acid is the conversion of SO2 into sulfur trioxide, SO3, using Equilibrium 1.
2SO2(g) + O2(g) 2SO3(g)      ∆H = −197 kJ mol−1 Equilibrium 1 An industrial chemist carries out some research into Equilibrium 1.
• The chemist fills a 10.2 dm3 container with SO2(g) at RTP, and then adds 12.0g of O2(g).
• The chemist adds the vanadium(V) oxide catalyst, and heats the mixture. The mixture is allowed to reach equilibrium at a pressure of 2.50atm and a temperature of 1000K.
• A sample of the equilibrium mixture is analysed, and found to contain 0.350 mol of SO3.

(ii) Determine the value of Kp for Equilibrium 1 at 1000K.
Show all your working.
Give your answer to 3 significant figures.

Hey, was the answer 27.2?

yes it was 27.2

How did u work this out? as i got 1.4^2 / 0.8 x 0.3^2 and ended up with 10.2 as my answer

In that case, you're just rubbish as using your calculator.

Have another go. Perhaps use brackets?

I have gotten 272.222... and I am unsure of why I am off by x10. For my final calculation I got 0.14^2 / 0.03^2 x 0.08; can you explain where I went wrong please?