Transcript Document
Final Jeopardy
Subterm 2
Solutions* Equilibrium* Acids & Bases* Thermochemistry* Redox Nuclear Chemistry* Organic Chemistry
THERMO
Calculate the H for this reaction: C 2 H 4 (g) + H 2 (g) C 2 H 6 (g) ( H f H f for C 2 H 4 (g) = 52.5 kJ/mol; for C 2 H 6 (g) = -84.7 kJ/mol)
(
84.7)
(52.5
0)
137.2
kJ
/
mol
Solutions
What is the maximum amount of KCl that can dissolve in 500 g of water? (solubility of KCl is 34 g / 100 g H 2 O at 20 C) 34 x 5 = 170 g
Solutions
What three operations makes a substance dissolve faster in a solvent?
Heating Agitation/stirring Smaller surface area/particle size
Solutions
If the solubility of a particular solute is 10g/100g H 2 O at 20 C, what solution concentrations would represent a supersaturated aqueous solution of that solute?
a) 5g/100g H20 b) 20g/200g H20 c) 25g/300g H20 d) 55g/500g H20
Solutions
What is the molarity of a solution that contains 6 moles of solute in 2 liters of solution?
6mol/2L = 3M
Solutions
What mass of sucrose, C 12 H 22 O 11 , is needed to make 500.0 mL of a 0.200M solution?
0.200M = x/0.500L
X = 0.1mol x (342g/mol) = 34.2 g
Solutions
To 205 mL of a 0.75M solution of KI, a student adds enough water to make 1.5 L of a more dilute KI solution. What is the morality of the new solution?
M1V1 = M2V2 M2 = 0.10 M
Solutions
What is the boiling point of a solution that contains 4.6 moles of KBr in 1500 g of water? (K b = 0.512
C/ m; gram formula mass of water = 18 g) T = kbmn T = (0.512)(4.6mol/1.5kg)(2) 103.1 o C
Soltions
What is the freezing point of a solution of 0.80 mol of LiBr in 850 mL of water? (K f 1.86
C/m) = -3.5 oC
Equilibrium
What is the expression for K eq reaction? 2H 2 O(g) 2H 2 for this (g) + O 2 (g)
k eq
(
H
2 ) 2 (
O
2 ) (
H
2
O
) 2
Equilibrium
Calculate the equilibrium constant for the production of MgO when the equilibrium concentrations are 0.030M of Mg, 0.020M for O 2 , and 2.0 M for MgO?
2
Mg
O
2 2
MgO k eq
(2.0) 2 (0.03) 2 (0.02) 2.2
x
10 5
Equilibrium
In an endothermic reaction at equilibrium, what is the effect of lowering the temperature?
The system will shift toward to reactants (to the left) and more reactants will be made.
Equilibrium
What is the effect of adding more hydrogen gas in the following equilibrium reaction?
C 2 H 2 (g) + H 2 (g) C 2 H 4 (g) More products will be made (the system will shift right)
Equilibrium
How does a decrease in pressure affect the following reaction? C 2 H 2 (g) + H 2 (g) C 2 H 4 (g) The system will shift towards the left (or the reactants)
Thermo
What does entropy measure?
The amount of chaos (disorder) in a system
Thermo
What physical state of carbon dioxide has the highest entropy (solid, liquid, or gas)?
GAS
Acids & Bases
When an acid reacts with a base, what two types of compounds are formed?
Salt and Water
Acids & Bases
If the [H + ] in a solution is 1 x 10 -1 the [OH ]?
mol/L, what is 1x10 -13 mol/L
Acids & Bases
If the pH is 4, what is the concentration of hydrogen ion?
1x10 -4 M
Acids & Bases
What is an acid according to Arrhenius?
Gives off hydrogen ions in solution
Acids & Bases
What characterizes a strong acid or base?
Dissociates completely in water
Acids & Bases
What is the concentration in normals of sulfuric acid if 34.5 mL of acid is neutralized by 20.0 mL of 1.0 M sodium hydroxide?
0.58 N
Acids & Bases
What does a buffer do?
A buffer helps keep the pH of a solution stable
Thermo
How much heat is absorbed by a 15.5 g piece of gold as it is heated from 4.5°C to 177.4°C? (the specific heat of gold is 0.129 J/g°C) q = mc J/g ° t q = (15.5g)(0.129 C)(172.9 ° C) q = 346 J
Thermo
How mcuh energy is needed to heat164.5 g ice at -27.6oC to 0.00oC?
9,490 J
Nuclear
1.
The half-life of radon-222 is four days. After how many days is the amount of radon 222 one-eighth of its original amount?
12 days
Nuclear
1.
What particle is needed to complete this nuclear reaction?
222 86
Rn
218 84
Po
2 4
___
Nuclear
What particle is needed to complete this reaction?
25 55
Mn
1 2
H
2 0 1
n
___
26 55
Fe
Nuclear
A piece of wood found in an ancient burial mound contains only one-fourth as much carbon-14 as a piece of wood cut from a living tree growing nearby. If the half-life (t 1/2 ) for carbon-14 is 5730 years, what is the approximate age of the ancient wood?
11,500 years
Nuclear
Nitrogen-13 decays to carbon-13 with a half-life of 10.0 minutes. Assume that you are given a starting mass of 2.00 grams of nitrogen-13. How many grams of nitrogen-13 will remain after 42.7 minutes?
0.104 grams
Final Jeopardy is next
Teams, place your bets You may bet between 0 pts - max points you have.
Each team will need to write down their final answer and bring it up for the judges to score.
You have as much time as you need (within reason)
Final Jeopardy
How much energy is needed to heat a 42.3 g sample of ice at – 35.7°C to steam at 112.0°C?
132 kJ