Answer:
The nucleus (center) of the atom contains the protons (positively charged) and the neutrons (no charge). The outermost regions of the atom are called electron shells and contain the electrons (negatively charged).
Answer: 0.5 g/cm^3
Density equals mass divided by volume so..
60/120 is 0.5 g/cm^3
Actual yield/Theoretical yield *100= Percentage yield. So Actual yield = Percentage yield*Theoretical yield.
Therefore actual yield= 90/100 * 1.09g = 0.98g
Actual yield: 0.98 g
Above it says the molecular weights are
NH3- 17g/mol and SF6-146 g/mol
Well 1 mole of SF6 is 146.048 grams (i added hte atomic masses of each element). So then the number of moles in 0.85 grams would be 0.00582000438 moles.
<span><span><span>= 1mole / </span><span>146.048g *</span></span> 0.85g</span>
so we would need 0.00582000438 moles of NH3 to have the same number of molecules.
One mole of NH3 is 17.030519999989988 grams (i added each atoms mass). so 0.00582000438 moles of NH3 would be:
<span><span><span>= 17.030519999989988 g / </span><span>mole * </span></span>0.00582000438moles</span>
that equals 0.09911770099 grams.
so 0.09911770099 grams is the answer if you round that you get about 0.1 grams
Answer:
There were originally 8 atoms of Potassium-40.
Explanation:
The half-life of a radioactive material is the time taken for half the original material to decay or the time required for a quantity of the radioactive substance to reduce to half of its initial value.
If the original material formed without any Argon-40, it means that the atoms originally present were Potassium-40 atoms.
Presently, there are 7 Argon-40 atoms for every 1 of Potassium-40, we can deduce the number of half-lifes the Potassium-40 has undergone as follows :
After one half-life, (1/2) there will be one Potassium-40 atom for every Argon-40 atom.
After a second half life, 1/2 × 1/2 = 1/4: there will be one Potassium-40 atom for every three atoms of Argon-40.
After a third half-life, 1/4 × 1/2 = 1/8: there will be one Potassium-40 atom for every 7 atoms of Argon-40.
Since there are 1/8 atoms of Potassium-40 presently, there were originally 8 atoms of Potassium-40.
