Answer to Question #142580 in General Chemistry for A

Question

What is the pressure of 1.75 moles of a gas that occupies 35 L at -50 ˚C?

Answer 1

Q142580

What is the pressure of 1.75 moles of a gas that occupies 35 L at -50 ˚C?

Solution:

In question, we are given,

moles of gas, n = 1.75moles

The Volume occupied by gas, V = 35L

Temperature of gas, T = -50⁰C.

Gas constant, R = 0.08206 L-atm/mol-K

We can use this information in the ideal gas formula, PV = nRT, and find the Pressure of the gas.

In the ideal gas equation, we must use Temperature in kelvin.

Convert -50⁰C to Kelvin by using the formula,

$T (K) = T(^0C ) + 273.15$

T(K) = -50 + 273.15 = 223.15K

Substitute all the given information in the ideal gas equation, we have

$$PV = nRT$$

P * 35L = 1.75mol * 0.08206 L-atm/mol-K * 223.15K ;

P * 35L = 32.045 L-atm

divide both the side by 35L we have

P*35L/35L = 32.045 L-atm/35L

P = 0.9156 atm ;

In question, the quantity with the least number of significant figures is 35L. It is in 2 significant figures.

So our final answer must also be in 2 significant figures.

0.9156 atm in 2 significant figures can be written as 0.92 atm.

Hence, the pressure of the gas is 0.92 atm.