# I need help with this problem?

A weather balloon has a volume of 750 L when filled with helium at 8oC at a pressure of 380 torr. What is the new volume of the balloon, where the pressure is 0.20 atm and the temperature is -45o C?

10500 L

80200 L

1520 L

1160 L

those are the answers

### 1 Answer

- pisgahchemistLv 75 months ago
Combined gas law .....

P1V1 / T1 = P2V2 / T2 ....... combined gas law

V2 = P1V1T2 / (T1P2) ........ solve for V2

V2 = 380 torr x 750L x 228K / 353K / (0.20 atm x 760 torr / 1 atm)

V2 = 1211 L ............ must be rounded to two significant digits: 1200L

========= Follow up ==========

When you write 8oC it looks remarkably like eighty Celsius, but it's eight Celsius... You would do well to not include the letter "o" when you mean degrees. Just write it as 8C, or actually put the "degree" symbol: 8°C.

P1V1 / T1 = P2V2 / T2 ....... combined gas law

V2 = P1V1T2 / (T1P2) ........ solve for V2

V2 = 380 torr x 750L x 228K / 281K / (0.20 atm x 760 torr / 1 atm)

V2 = 1521 L ............ must be rounded to two significant digits: 1500L

The data is given to two significant digits, but your answer choices are given to three significant digits. That's a problem. The choices should be given to two significant digits, which makes the answer 1500L, not 1520L.