Answer: 8.1 days
Explanation:
Expression for rate law for first order kinetics is given by:
where,
k = rate constant
t = age of sample
a = let initial amount of the reactant = x
a - x = amount left after decay process=
a) to find rate constant
Half life is the amount of time taken by a radioactive material to decay to half of its original value.
b) for completion of one fourth of reaction
Thus after 8.1 days , one fourth of original amount will remain.
Answer:
Explanation:
First, find the molar mass of calcium (Ca). This can be found on the Periodic Table.
Next, find the number of moles.
Avogadro's Number tells us the number of atoms in one mole.
Therefore, there are 6.023*10²³ atoms in 1 mole.
We have 6.023*10²³ atoms of calcium, so it must also be 1 mole of calcium.
Finally, find the mass. Set up a proportion using the molar mass of calcium.
Multiply. The moles (mol Ca) will cancel.
There are <u>40.08 grams </u>in 6.023*10²³ atoms of calcium.