Immediately after the chernobyl nuclear accident, the concentratiorn of 137cs (cesium 137) in cow's milk was 12,000 bq/l (a becquerel is a measure of radioactivity; one becquerel equals one radioactive disintegration per second). assume that the only reaction by which the 137cs was lost from the soil was through radioactive decay. also assume that the concentration in cows milk is directly proportional to the concentration in the soil. calculate the concentration of 137cs in cow's milk (from feeding on grass in the soil) 5 years after the accident given a half-life for 137cs of 30 years.

The concentration of cow's milk after 5 years is 10691 Bq/L

Explanation:

All the radioactive reactions follow first order kinetics.

The equation used to calculate rate constant from given half life for first order kinetics:

We are given:

Putting values in above equation, we get:

The equation used to calculate time period follows:

where,

= initial concentration of Cow's milk = 12000 Bq/L

N = Concentration of cow's milk after 5 years = ?

t = time = 5 years

k = rate constant =

Putting values in above equation, we get:

Hence, the concentration of cow's milk after 5 years is 10691 Bq/L

chemistry sucks a**

explanation:

answer : one can design an experiment using a liquid and an additive that can be added to the liquid and observe the chemical changes in the reaction species.

one would need a beaker which is filled with a known amount of the liquid in which thermometer is placed to measure the temperature changes; after addition of the additive to the liquid solution one can note down the temperature change and find whether the reaction is endothermic or exothermic in nature. by subtracting the initial temperature value with the final temperature one can find the temperature changes.

various combinations of liquid and additive can be used. liquid in this case can be a known quantity of water and additives can be epsom salt or without epsom salt the experiment can be conducted to notice the changes. water and ice, hydrogen peroxide and dry yeast, vinegar and baking soda,etc.