Calculate the amount of HCN that gives the lethal dose in a small laboratory room measuring 12.0 ft×15.0 ft×9.10ft.?

becca 12/07/2017 at 01:44. 4 answers
Science & Mathematics Chemistry

Hydrogen cyanide, HCN, is a poisonous gas. The lethal dose is approximately 300. mg HCN per kilogram of air when inhaled. The density of air at 26 ∘C is 0.00118 g/cm3.

4 Answers


Dr W 12/07/2017 at 12:45.

first of all.. that toxicity data isn't correct. It should have a type and a time and a beast attached to it. Imagine a room with 1000ppm HCN vs a room with 100ppm HCN. It wouldn't take as long to breathe in a lethal dose of HCN in that concentrated room than it would in the dilute room. And rats and mice and monkeys and dogs and humans all respond differently to HCN absorption. And the way we test might be... to a concentration that kills 50% of a test population in say 10min vs a concentration where only 1 beast has ever died.

examples

.. LC50 = 323 mg HCN / kg air @ 5min for mouse

.. LC50 = 208 mg HCN / kg air @ 30 min for rabbit

.. LCLo = 200 mg HCN / kg air @ 10 min for human

those mean

.. 50% of a test population of a particular mouse breed will die after 5 min exposure of 323mg / kg

.. 50% of a test population of a particular breed of rabbit will die after a 30 min exposure of 208 mg / kg

.. the lowest ever recorded human death for 200mg HCN / kg air occured after 10 min exposure.

**********

in any case, your 300mg / kg air is problably

.. LC50 = 300mg HCN / kg air for 5 min exposure of a mouse. Humans are different! exposure time would be different!

point is..

.. lower concentrations can be just as deadly if the exposure is longer

.. higher concentrations can be easily survived if exposure time is short

.. it's not the concentration that makes it lethal... it's the concentration + exposure time.

anyway

(12.0ft * 15.0ft * 9.10ft) * (12in / 1ft)³ * (2.54cm / 1in)³ * (1.18x10^-6kg air / cm³) * (300mgHCl / kg air) = 1.64x10^4mg HCN


Roger the Mole 12/07/2017 at 12:45.

(12.0 ft × 15.0 ft × 9.10 ft) x (28316.847 cm^3/ft^3) x (0.00118 g/cm^3) / (1000 g/kg) x (0.300 g HCN/kg) = 16.4 g HCN


Ricki 12/07/2017 at 12:45.

Volume of room = 1638 ft^3 = 46355 L

0.00118 g/cm3 = 0.00118 kg/L

Mass of air = 46355 L * 0.00118 kg/L = 54.7 kg

53.7 kg air * 300 mg/kg air = 16400 mg


Roderick Matheson 12/07/2017 at 12:45.

I'll be honest with you, I have no idea what you said.

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