Ap Chemistry Unit 8.03 Question

Question

A 0.1931mol sample of dry ice, CO2(s) is added to an empty balloon. After the balloon is sealed, the CO2(s) sublimes and the CO2(g) in the balloon eventually reaches a temperature of 21.0°C and pressure of 0.998atm. The physical change is represented by the following equation.

CO2(s)→CO2(g)ΔHsublimation=?

What is the sign (positive or negative) of the enthalpy change for the process of sublimation? Why?

What are all the numerical values of the quantities, with appropriate units, that are needed to calculate the volume of the balloon?

What is the final volume, in liters, of the balloon?

Answer 1

You need moles for this, so need molecular mass. Then pV = nRT so also need a value for R in units to match the rest of the givens.

Sublimation is always endothermic. You can keep things cold with dry ice, until it finishes subliming!

How heavy would the balloon be measured as (subtract the tare mass of the balloon)? Hint: It is NOT the mass of the CO2 contents!! Why?

-- Cheers, --Mr. d.