Answer:
7.6 days
Explanation:
Radon is a radioactive element and Radon-222 is it's most stable isotope. The half-life of Radon-222 has been found to be approximately 3.8 days.
Let, the initial amount of the Rn-222 = 1 = A
Final amount = 
= A'
We will use the following relation for calculating time elapsed in the decay
Thus,
We can write is as,
Since the base in both sides are equal, powers can also be equal and thus,
So, t = 7.6 days
we're the rest of the question
Answer:
1360kJ are evolved
Explanation:
When 1mole of H2 reacts with 1/2 moles O2 producing 1 mole of water and 241.8kJ.
To solve this question we need to find the limiting reactant knowing were added 90g of H2 and 90g of O2 as follows:
<em>Moles H2 -Molar mass: 2g/mol-</em>
90g H2 * (1mol / 2g) = 45 moles
<em>Moles O2 -Molar mass: 32g/mol-</em>
90g * (1mol / 32g) = 2.81moles
For a complete reaction of 2.81 moles of O2 are needed:
2.81 moles O2 * (1mol H2 / 1/2 mol O2) = 5.62 moles H2
As there are 45 moles, H2 is the excess reactant and O2 the limiting reactant.
As 1/2 moles O2 produce 241.8kJ, 2.81 moles will produce:
2.81 moles O2 * (241.8kJ / 1/2moles O2) =
<h3>1360kJ are evolved</h3>
Answer:
Explanation:
<u>1) Data:</u>
a) M = 0.5 M
<u>Note</u>: since the question is about volume (liters) and moles of solute, the correct unit for the concentration of the hydroxide solution is M (upper case) which is the unit for molarity. Lower case m is used for molality, and you cannot calculate the volume of the solution unless you know some other data, e.g. density of the solution.
b) n = 2
c) V (in liters) = ?
<u>2) Formula:</u>
Molarity is the number of moles of solute per liter of solution:
<u>3) Solution:</u>
a) Clear V from the formula: V (in liters) = M / n
b) Substitute: V (in liters) = 2 moles / 0.5M = 4 liters ← answer
<span> When a sodium atom transfers an electron to a chlorine atom, forming a sodium cation (Na+) and a chloride anion (Cl-), both ions have complete valence shells, and are energetically more stable</span>
<span>hope this helps</span>
