Please help and show work 1. Calculate the number of moles of oxygen in a 12.5 L tank if the pressure is 2530 kPa and the temperature is 22 degrees C.
2. Calculate the pressure of 0.30 moles of nitrogen dioxide in a 2.7 L container if the temperature is 27 degrees C.
3. A 35 L tank contains 7.0 mol of compressed air at 500 KPa pressure, what is the temperature in Kelvin and Celsius?
4. Calculate the volume that 2.25 mol of air occupies at STP

Answer asap need by wednesday morning explain how a buffer works, using an ethanoic acid/sodium ethanoate system including how the system resists changes in ph upon addition of a small amount of base and upon addition of a small amount of acid respectively. include the following calculations in your i. calculate the ph of a solution made by mixing 25cm3 0.1m ch3cooh and 40cm3 0.1m ch3coo-na+. [ka = 1.74 x 10-5 m] ii. calculate the ph following the addition of a 10cm3 portion of 0.08 m naoh to 500cm3 of this buffer solution. iii. calculate the ph following the addition of a 10cm3 portion of 0.08 m hcl to 200cm3 of the original buffer solution.