Calculate in joules the work done by 10 grams of CO2 when it sublimes against a pressure of 1 atm to for?

gaseous CO2 at 0 degrees celsius. The volume of solid CO2 can be neglected and gaseous CO2 can be umed to behave ideally. The answer is - 516 J, but I can not figure out how to show my work for this problem. I have done it numerous times and still haven't came up with - 516 J. Can anyone help PLEASE?