Answer:
n ≈ 2.42 moles
General Formulas and Concepts:
<u>Chem</u>
Ideal Gas Law: PV = nRT
- P is pressure in mmHg
- V is volume in liters
- n is number of moles
- R is a constant (62.4 L · mmHg/mol · k)
- T is temperature in Kelvins
K = °C + 273
Explanation:
<u>Step 1: Define</u>
V = 50.2 L
P = 755 mmHg
T = -22.0°C = 251 K
<u>Step 2: Find moles </u><em><u>n</u></em>
(755 mmHg)(50.2 L) = n(62.4 L · mmHg/mol · k)(251 K)
37901 mmHg · L = n(15662.4 L · mmHg/mol)
n = 2.41987 moles
<u>Step 3: Check</u>
<em>We are given 3 sig figs. Follow sig fig rules.</em>
2.41987 moles ≈ 2.42 moles
Answer:
egg: endothermic
candle: exothermic
plaster and water : exothermic
salt and water: neither
<u>1) determine which formula you are going to use.</u>
<u>2) list your information.</u>
P = 101.325 kPa
V = 3.57 L
n = ?
R = 8.314
T = 273.15 K
<u>3) rearrange your formula</u>
<u>4) solve.</u>
<em>n = 0.159 mol NH₃</em>
75% is the chance that they will have detached earlobes
This uses the concept of freezing point depression. When faced with this issue, we use the following equation:
ΔT = i·Kf·m
which translates in english to:
Change in freezing point = vant hoff factor * molal freezing point depression constant * molality of solution
Because the freezing point depression is a colligative property, it does not depend on the identity of the molecules, just the number of them.
Now, we know that molality will be constant, and Kf will be constant, so our only unknown is "i", or the van't hoff factor.
The van't hoff factor is the number of atoms that dissociate from each individual molecule. The higher the van't hoff factor, the more depressed the freezing point will be.
NaCl will dissociate into Na+ and Cl-, so it has i = 2
CaCl2 will dissociate into Ca2+ and 2 Cl-, so it has i = 3
AlBr3 will dissociate into Al3+ and 3 Br-, so it has i = 4
Therefore, AlBr3 will lower the freezing point of water the most.