Radioactive decay is first order in the decaying isotope. For example, strontium-90 contained in fallout from nuclear explosions decays to yttrium-90 and a beta particle. Write the rate law for the decay of strontium-90.

Can you please take me step by stem through this problem?

rate = k(Sr-90)

What is the rate

also what is k and Sr i am so confused

For a first order reaction

rate = k*(concentration)^1
k is a constant.
Your question asks for the expression, not for an answer numerically. They don't give a k and they don't list a concentration.
k can be determined from
k = 0.693/t1/2 and you can evaluate that by looking up the half life of Sr-90 and plugging it into the equation.

Sure! To write the rate law for the decay of strontium-90, we need to understand that the decay process is first order. This means that the rate of decay is proportional to the concentration of strontium-90.

Step 1: Write the general form of a first-order reaction rate law:
Rate = k [A]
where Rate is the rate of decay, k is the rate constant, and [A] is the concentration of the reactant (in this case, strontium-90).

Step 2: Substitute the reactant into the rate law.
In this case, the reactant is strontium-90, so the rate law becomes:
Rate = k [Sr-90]

Step 3: Finalize the rate law.
Since the concentration of strontium-90 is typically denoted as [Sr-90], the final rate law for the decay of strontium-90 is:
Rate = k [Sr-90]

That's it! The rate law for the decay of strontium-90 is simply Rate = k [Sr-90], where [Sr-90] represents the concentration of strontium-90 and k is the rate constant.