HCO2H(g) �¨ CO2(g) + H2(g) The half-life for the reaction at 550 �‹C is 24 seconds. How many seconds does it take for the formic acid concentration to decrease by 75%?

Answer 1

.25=e^(-.692t/24)
take the ln of each side, solve for t. You need to do that calc for practice.

Now, the easy way with the numbers given.
In the first half life, you have .50 left
in the second half life, you have .25 left....which means .75 has been consumed.
two half lives...

Answer 2

If a movie has 0.16 hour remaining, how many seconds of movie remain?