Answer:
The percent abundance of oxygen-18 is 1.9066%.
Explanation:
The average atomic mass of oxygen is given by:
Where:
m: is the atomic mass
%: is the percent abundance
Since the sum of the percent abundance of oxygen isotopes must be equal to 1, we have:
Hence, the percent abundance of O-18 is:
Hence, the percent abundance of oxygen-18 is:
Therefore, the percent abundance of oxygen-18 is 1.9066%.
I hope it helps you!
Answer:
<em>293.99 g </em>
OR
<em>0.293 Kg</em>
Explanation:
Given data:
Lattice energy of Potassium nitrate (KNO3) = -163.8 kcal/mol
Heat of hydration of KNO3 = -155.5 kcal/mol
Heat to absorb by KNO3 = 101kJ
To find:
Mass of KNO3 to dissolve in water = ?
Solution:
Heat of solution = Hydration energy - Lattice energy
= -155.5 -(-163.8)
= 8.3 kcal/mol
We already know,
1 kcal/mol = 4.184 kJ/mole
Therefore,
= 4.184 kJ/mol x 8.3 kcal/mol
= 34.73 kJ/mol
Now, 34.73 kJ of heat is absorbed when 1 mole of KNO3 is dissolved in water.
For 101 kJ of heat would be
= 101/34.73
= 2.908 moles of KNO3
Molar mass of KNO3 = 101.1 g/mole
Mass of KNO3 = Molar mass x moles
= 101.1 g/mole x 2.908
= 293.99 g
= 0.293 kg
<em><u>293.99 g potassium nitrate has to dissolve in water to absorb 101 kJ of heat. </u></em>
57.0 is it rounded to three sig figs. You count three spaces then round from there, which would be the zero and you would round down because the four is there.
They use it because it's standerize and evidence vase
Well the multiple choices for this question would be helpful, but from my own knowledge I would say:
Magnetic fields have north and south magnetic poles.
Magnetic fields have various characteristics which includes; they originate from the north poles and flow towards the south poles, they are exhibited in the form of magnetic field lines. Magnetic fields lines never cross one another,they all have the same strength and seek the path of least resistance between opposite magnetic poles etc.
