HW Question help!!!!?

Question

Nitroglycerin (22.7 g/mol) releases a large amount of energy and gaseous products upon decomposition. If 10.00g of nitroglycerin decomposes in an evacuated 1.00L flask, what is the pressure inside the flask? Assume the temperature is 4.00 X 10^2K and the flask survives the explosion.

Answer 1

Because you are not given any additional information, I'm going to assume you are working in an ideal system.  You are given temperature, volume and enough information to find the number of moles of gas in the flask, so you can use the ideal gas equation (PV = nRT) to solve for the pressure.

First let's solve for moles of gas, n.  Since we are given the molar mass of nitroglycerin and the mass of the nitroglycerin sample in the flask, we can convert grams of nitroglycerin into moles of nitroglycerin:

10.00g nitroglycerin (1 mol nitroglycerin/22.7g nitroglycerin) = 0.441 mol nitroglycerin

We now rearrange the ideal gas equation to solve for P (P = nRT/V) and insert our information:

n = 0.441 mol

R = 0.0821 L*atm/mol*K

T = 400 K

V = 1.00L

Solve:

P = [(0.441 mol)(0.0821 L*atm/mol*K)(400K)] / [1.00 L]

P = 14.5 atm

Hope this helps.