Using dimensional analysis, we can find the moles of strontium by comparing the mass of strontium to it's atomic mass.
You can find the atomic mass of Sr on the periodic table:
Atomic Mass Sr = 87.62g/mol
In case you are not familiar, dimensional analysis works like this:
(what we know) x (conversion factor) = what we are looking for
The conversion factor compares the units of what we know to the units of what we are looking for. In this case, the conversion factor is:
1 mol/87.62g
The important thing to note about the conversion factor is that you want to be able to cancel out the units of your given measurement (in this case, it is the mass)
So, our full solution will be:
moles Sr = (175.24 g)x(1 mol/87.62 g)
(cancel out the mass units)
moles Sr = 175.24 x 1 mol/87.62
= 2.00 mol Sr
Hope this helped you!
Answer : Half life and radioactive decay are inversely proportional to each other.
Explanation :
The mathematic relationship between the half-life and radioactive decay :
................(1)
where,
N = number of radioactive atoms at time, t
= number of radioactive atoms at the beginning when time is zero
e = Euler's constant = 2.17828
t = time
= decay rate
when 
then the number of radioactive decay become half of the initial decay atom i.e 
.
Now substituting these conditions in above equation (1), we get
By rearranging the terms, we get
Now taking natural log on both side,
By rearranging the terms, we get
This is the relationship between the half-life and radioactive decay.
Hence, from this we conclude that the Half life and radioactive decay are inversely proportional to each other. That means faster the decay, shorter the half-life.
<h3>
Answer:</h3>
63 years
Eighth
The number of half lives
<h3>
Explanation:</h3>
It will take 63 years for half of the sample to decay
In 189 years, eighth of the sample will be left
Scientists can figure out how old a sample is by multiplying the number of half lives by the length of the half life.
Half life is the time taken by a radioactive sample to decay to half of the original amount.
Therefore, for a radioactive element with a half-life of 63 years, it will take 63 years for the sample to decay to half of the original amount.
After 189 years, only an eighth of the sample will be left.
That is, 189 years is equivalent to 3 half-lives
Therefore, if the original amount is 1, then;
1 → 0.5 → 0.25 → 0.125
Thus, scientists can figure out how old a sample is by multiplying the number of half lives by the length of the half life.
2Na + Cl2 ----> 2NaCl
.: product have to be " 2NaCl "
Answer:
Tell students that sometimes when two (or more) substances are mixed together, a change occurs and another substance (or substances) is created. This is called a chemical reaction. Gas may form, heat may be produced, and color may change. These types of changes indicate that a chemical reaction has occurred.
