#### sunny87

Hi everyone, I'd appreciate some help with this problem (it is driving me crazy)

Humpback whales have large lungs (volume of 3600 L). If a whale takes a full breath of air at the surface (pressure= 1.000 atm or 101.3 kPa) and the internal body temperature of the whale is 36.40°C, how many grams of oxygen gas are in the whales lungs? ( R= 8.314 kPa L/ K mol ; R= 0.0821 atm L/K mol).

what I did:
1- pV= nRt so I rearrange the formula to n=pv/Rt, chaged temperature in kelvin (from 36,4°C to 309.4K)

2- n= (1 atm×3600L )/ (0.0821atm/k mol × 309.4K) , so n = 141.74 mol

3- moles to grams: 141.74 mol × 32 g/mol of oxygen = 4535 g

So my final answer is 4535 and it appears to be wrong, i have done it a million times and I don't find the mistake I must have made. Please help me!

#### topsquark

Forum Staff
Hi everyone, I'd appreciate some help with this problem (it is driving me crazy)

Humpback whales have large lungs (volume of 3600 L). If a whale takes a full breath of air at the surface (pressure= 1.000 atm or 101.3 kPa) and the internal body temperature of the whale is 36.40°C, how many grams of oxygen gas are in the whales lungs? ( R= 8.314 kPa L/ K mol ; R= 0.0821 atm L/K mol).

what I did:
1- pV= nRt so I rearrange the formula to n=pv/Rt, chaged temperature in kelvin (from 36,4°C to 309.4K)

2- n= (1 atm×3600L )/ (0.0821atm/k mol × 309.4K) , so n = 141.74 mol

3- moles to grams: 141.74 mol × 32 g/mol of oxygen = 4535 g

So my final answer is 4535 and it appears to be wrong, i have done it a million times and I don't find the mistake I must have made. Please help me!
The only thing I can suggest is that your gas constant is slightly off. I used R = 0.082057 (L atm)/(K mol). That got me a result of 4537 g. (There is a link to a wikipedia article under the "R = " portion here.)

-Dan