Answer:
12.9 L Kr
General Formulas and Concepts:
<u>Chemistry - Gas Laws</u>
- Using Dimensional Analysis
- STP (Standard Conditions for Temperature and Pressure) = 22.4 L per mole at 1 atm, 273 K
Explanation:
<u>Step 1: Define</u>
0.575 mol Kr
<u>Step 2: Identify Conversions</u>
1 mol= 22.4 L at STP
<u>Step 3: Convert</u>
<u />
= 12.88 L Kr
<u>Step 4: Check</u>
<em>We are given 3 sig figs. Follow sig fig rules and round.</em>
12.88 L Kr ≈ 12.9 L Kr
This is a freezing point depression problem, so it will use the equation:
ΔT = i Kf<span> m
</span>
i = 1 (naphthalene does not dissociate further when dissolved)
Kf = 7.10 C/m (a constant for paradichlorobenzene, which you'd be given)
m = moles of solute / kg of solvent; moles of solute = 4.78 / 128.2 = 0.0373; kg of solvent = 0.032; m = 0.0373 / 0.032 = <span>1.166m
</span>ΔT = 1 x 7.10 x 1.166 = 8.279 C
This means the normal freezing point of pure paradichlorobenzene is decreased by 8.279 C; the normal freezing point (again, something you'd be given) is 53.5 C, so the new freezing point would be 53.5 - 8.279 = 45.221 C.
Answer:the molecular formula
Explanation:
Not too sure about first question, Second is D. 41, 406 J.
7.2 / 2.4 = 3 half-lives
(1/2)3 = 0.125 (the amount remaining after 3 half-lives)
100.0 g x 0.125 = 12.5 g remaining
