A tank contains helium gas at 490mmHg, nitrogen gas at 0.75atm, and neon at 520 torr. What is the total pressure in atm?
A. 1.5 atm
B. 1.0*10^3
C. 1600 atm
D. 2.1 atm
E. 0.55 atm
The answer is 2.1 atm, but I don't understand why

Question

A tank contains helium gas at 490mmHg, nitrogen gas at 0.75atm, and neon at 520 torr. What is the total pressure in atm?
A. 1.5 atm
B. 1.0*10^3
C. 1600 atm
D. 2.1 atm 
E. 0.55 atm 
The answer is 2.1 atm, but I don't understand why

jfraser · Answer

you need to convert the first and third pressures into atm, so they can be added together

jfraser · Answer

since $$1atm = 760mmHg$$then $$490 \cancel{mmHg} * \frac{1atm}{760 \cancel{mmHg}}  = 0.645atm$$

jfraser · Answer

each gas provides its own partial pressure to the whole pressure, but they can't be added together unless they are in the same unit

anonymous · Answer

Wait so what about the third pressure??

anonymous · Answer

How do I convert "torr" to "atm"?

anonymous · Answer

Is it true that 760 torr = 1 atm?

jfraser · Answer

it is