Answer:
40%
Explanation:
We'll begin by obtaining the molar mass of MgO. This is illustrated below:
Molar Mass of MgO = 24 + 16 = 40g/mol
Observing the formula MgO, we have 1 atom of O in it.
The percentage composition by mass of oxygen in MgO is given by:
Mass of O/Molar Mass of MgO x 100
= 16/40 x 100 = 40%
The age of the fossil given the present amount of Carbon-14 is given in the equation,
A(t) = A(o)(0.5)^t/h
where A(t) is the current amount, A(o) is the initial amount, t is time and h is the half-life. Substituting the known values to the equation,
A(t) / A(o) = 0.125 = (0.5)^(t/5730)
The value of t from the equation is 17190.
Thus, the age of the fossil is mostly likely to be 17190 years old.
Answer:
Explanation:
Hello,
In this case, for the acid dissociation of formic acid (HCOOH) we have:
Whose equilibrium expression is:
![Ka=\frac{[H^+][HCOO^-]}{[HCOOH]}](https://tex.z-dn.net/?f=Ka%3D%5Cfrac%7B%5BH%5E%2B%5D%5BHCOO%5E-%5D%7D%7B%5BHCOOH%5D%7D)
That in terms of the reaction extent is:
Thus, solving for 
which is also equal to the concentration of hydrogen ions we obtain:
![[H^+]=0.00528M](https://tex.z-dn.net/?f=%5BH%5E%2B%5D%3D0.00528M)
Then, as the pH is computed as:
![pH=-log([H^+])](https://tex.z-dn.net/?f=pH%3D-log%28%5BH%5E%2B%5D%29)
The pH turns out:
Regards.
The answer is 32.43 because when you round the number next to the hunthers place (witch in this problem would be the 1) has to be 5 or hight to raise the number to the left of it and if it is lower you just take the two number and that is your answer.
