Chemistry Questions??

Question

Hey guys, need help with these questions..

1. Two items have a flash points of -15 degrees Fahrenheit, and 80 degrees Celsius.. which one poses the greater fire hazard?

2. Upper explosive limit of liquid cumene is 0.9% and 6.5% When exposed to an ignition source, will cumene vapors ignore in the air at each of the following: 10%, 0.09%, and 6% (basically yes or no)

Answer 1

1. The flash point of a flammable liquid is the lowest temperature at which it can form an ignitable mixture in air.
The one that will becove flammable at -15 degrees is the greater danger.

2. The explosive limit of a gas or a vapour, is the limiting concentration (in air) that is needed for the gas to ignite and explode. There are two explosive limits for any gas or vapor, the lower explosive limit (LEL) and the upper explosive limit (UEL). At concentrations in air below the LEL there is not enough fuel to continue an explosion; at concentrations above the UEL the fuel has displaced so much air that there is not enough oxygen to begin a reaction. Concentrations of explosive gases are often given in terms of percent of lower explosive limit (%LEL).

Yes, no, yes

Answer 2

1) the first one.

2) If the explosive limits are 0.9% and 6.5%, then it will only explode at conentrations in between these two. "Ignore in the air" doesn't really make sense, so I'll guess you meant to type "ignite in the air" in which case the answers are no, no, yes.

Answer 3

1) The one with -15 degrees F

2) Only at 10%