The decomposition of n2o5(g) —> no2(g) + no3(g) proceeds as a first order reaction with a half life 30.0s at a certain temperature.
if the initial concentration [n2o5]0 = 0.400 m, what is the concentration after 120 seconds?
a)0.050
b)0.200
c)0.025
d)0.100

Explanation:

The half-life (30.0 s) is the time it takes for half of the N₂O₅ to react.  

After one half-life, half (50 %) of the original amount will remain.  

After a second half-life, half of that amount (25 %) will remain, and so on.  

We can construct a table as follows:  

the answer is the first option

explanation:

just googled it m8. not that hard

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