How many moles of helium are needed to fill a balloon to a volume of 4.9 at 296°K and 0.78 atm?

The number of moles of helium needed is 0.157 moles helium

Explanation:

Step 1: Data given

Volume of the balloon = 4.9 L

Temperature= 296 K

Pressure = 0.78 atm

Step 2: Calculate moles of helium gas

p*V = n*R*T

⇒with p = the pressure = 0.78 atm

⇒with V = the volume = 4.9 L

⇒with n = the number of moles of the helium gas = TO BE DETERMINED

⇒with R = the gas constant = 0.08206 L*atm/mol* K

with T = the temperature = 296 K

n = (p*V) / (R*T)

n = (0.78 atm* 4.9 L) / (0.08206 L*atm/mol*K * 296 K)

n = 0.157 moles of helium

The number of moles of helium needed is 0.157 moles helium

answerambulatory;

the correct answer would be b) volume versus temperature, because they are also directly proportional.