Final Jeopardy

Subterm 2Solutions*

Equilibrium*

Acids & Bases*

Thermochemistry*

Redox

Nuclear Chemistry*

Organic Chemistry

THERMO

Calculate the H for this reaction:C2H4(g) + H2(g) C2H6(g)

(H f for C2H4(g) = 52.5 kJ/mol;

Hf for C2H6(g) = -84.7 kJ/mol)

€

(−84.7) − (52.5+0) = −137.2kJ /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 H2O at 20C)

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 H2O at 20C, 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

SolutionsWhat 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, C12H22O11, 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? (Kb = 0.512C/ m; gram formula mass of water = 18 g)

T = kbmn

T = (0.512)(4.6mol/1.5kg)(2)

103.1 oC

Soltions

What is the freezing point of a solution of 0.80 mol of LiBr in 850 mL of water? (Kf = 1.86C/m)

-3.5 oC

Equilibrium

What is the expression for Keq for this reaction? 2H2O(g) 2H2(g) + O2(g)

€

keq

=(H

2)2 (O

2)

(H2O)2

Equilibrium

Calculate the equilibrium constant for the production of MgO when the equilibrium concentrations are 0.030M of Mg, 0.020M for O2, and 2.0 M for MgO?

€

2Mg+O2

→ 2MgO

keq

=(2.0)2

(0.03)2 (0.02)= 2.2x105

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?

C2H2(g) + H2(g) C2H4(g)

More products will be made

(the system will shift right)

Equilibrium

How does a decrease in pressure affect the following reaction?

C2H2(g) + H2(g) C2H4(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 mol/L, what is the [OH-]?

1x10-13mol/L

Acids & Bases

If the pH is 4, what is the concentration of hydrogen ion?

1x10-4M

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 = mctq = (15.5g)(0.129 J/g°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?

€

86

222Rn→84

218Po+ ___

€

2

4α

Nuclear

€

25

55Mn+1

2H →20

1n + ___

What particle is needed to complete this reaction?

€

26

55Fe

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 (t1/2) 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