Answer:
The half-life of a radioisotope describes the amount of time it takes for said isotope to decay to one-half the original amount present in the sample.
Nitrogen-13, because it has a half-life of ten minutes, will experience two half-lives over the course of the twenty minute period. This means that 25% of the isotope will remain after this.
0.25 x 128mg = 32mg
32mg of Nitrogen-13 will remain after 20 minutes.
A) Nitrogen has an ATOMIC mass number of 14, but nitrogen gas consists of N₂ molecules, so the mass to use in this problem is 28 g/mol. Rates of effusion ∝ 1/√(mass), so
<span>√(mass unknown) /√28 = (rate N₂ effusion)/(rate unknown effusion) = 1.59 </span>
<span>∴ mass unknown = (1.59)²(28) = 70.78 g/mol </span>
<span>B) One possible gas that comes close for this mass is NF₃.</span>
Answer: mole
A formula unit represents the simplest ratio of elements in a mole of an ionic compound.
Explanation:
The formula unit, also known as the empirical formula, gives the simplest whole number ratio of the components of the elements in a mole of an ionic compound.
Thus, the formula unit and the molecular formula of a compound can be the same.
For example: Glucose with C6H12O6 will have a formula unit of CH2O. Thus, the simplest ratio of carbon, hydrogen and oxygen in glucose is 1:2:1
Isolated systems does not allow any matter or energy to be exchanged.
Answer:
7.22*10^24 molecules
Explanation:
Since one mole has 6.02*10^23 you'd multiply that number by 12
that equals 7.224*10^24 but you need sig figs
