The compound Xe(CF3)2 decomposes in a first-order reaction to elemental Xe with a half-life of 30.0 min. If you place 4.5 mg of Xe(CF3)2 in a flask, calculate how long you must wait until only 0.25 mg of Xe(CF3)2 remains?

Answer : The time passed by the sample is,

Explanation :

Half-life = 30.0 min

First we have to calculate the rate constant, we use the formula :

Now we have to calculate the time passed.

Expression for rate law for first order kinetics is given by:

where,

k = rate constant  =

t = time passed by the sample  = ?

a = initial amount of the reactant  = 4.5 mg

a - x = amount left after decay process =0.25 mg

Now put all the given values in above equation, we get

Therefore, the time passed by the sample is,

chemical properties are the characteristic of matter which can only be observed by changing the chemical identity of a sample like flammability reactivity and toxicity.

you need to take a look at the periodic system in order to sort these elements into pairs that would most likely exhibit similar chemical properties. first, you need to find elements that are found in the same group (groups are vertical in the periodic system), and then to see whether they have the same valence number. if they meet these criteria, they will have similar properties.

the first pair: ne (neon) and kr (krypton), are noble gases found in group 8

the second pair: li (lithium) and k (potassium), found in group 1

the third pair: s (sulfur) and te (tellurium), found in group 6